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2023, Vol. 76, No. 1　Online: 15 January 2023

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An efficient Hauser-base electrolyte for rechargeable magnesium batteries Mingxiang Cheng, Yaru Wang, Duo Zhang, Shuxin Zhang, Yang Yang, Xuecheng Lv, Jiulin Wang, Yanna NuLi 2023, 76(1): 1-10.  DOI: 10.1016/j.jechem.2022.08.037 Abstract ( 298 )   PDF (2590KB) ( 175 )   Rechargeable magnesium batteries (RMBs) are considered the promising candidates for post lithium-ion batteries due to the abundant storage, high capacity, and dendrite-rare characteristic of Mg anode. However, the lack of practical electrolytes impedes the development and application of RMBs. Here, through a one-step reaction of LiCl congenital-containing Knochel-Hauser base TMPL (2,2,6,6-tetramethylpiperidinylmagnesium chloride lithium chloride complex) with Lewis acid AlCl3, we successfully synthesized an efficient amino-magnesium halide TMPLA electrolyte. Raman and mass spectroscopy identified that the electrolyte comprises the typical di-nuclear copolymer [Mg2Cl3·6THF]+ cation group and [(TMP)2AlCl2]- anion group, further supported by the results of density functional theory calculations (DFT) and the Molecular dynamics (MD) simulations. The TMPLA electrolyte exhibits promising electrochemical performance, including available anodic stability (>2.65 V vs. SS), high ionic conductivity (6.05 mS cm-1), and low overpotential (<0.1 V) as well as appropriate Coulombic efficiency (97.3%) for Mg plating/stripping. Both the insertion Mo6S8 cathode and conversion CuS cathode delivered a desirable electrochemical performance with high capacity and good cycling stability based on the TMPLA electrolyte. In particular, when compatible with low cost and easily synthesized CuS, the CuS||Mg cell displayed an extremely high discharge capacity of 458.8 mAh g-1 for the first cycle and stabilized at 170.2 mAh g-1 with high Coulombic efficiency (99.1%) after 50 cycles at 0.05 C. Our work proposes an efficient electrolyte with impressive compatibility with Mg anode and insertion/conversion cathode for practical RMBs and provides a more profound knowledge of the Lewis acid-base reaction mechanisms.

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In-situ oriented oxygen-defect-rich Mn—N—O via nitridation and electrochemical oxidation based on industrial-scale Mn2O3 to achieve high-performance aqueous zinc ion battery Yao Liu, Shuailong Guo, Wei Ling, Mangwei Cui, Hao Lei, Jiaqi Wang, Wenzheng Li, Qingjiang Liu, Lukuan Cheng, Yan Huang 2023, 76(1): 11-18.  DOI: 10.1016/j.jechem.2022.08.038 Abstract ( 12 )   PDF (1779KB) ( 10 )   As a general problem in the field of batteries, materials produced on a large industrial scale usually possess unsatisfactory electrochemical performances. Among them, manganese-based aqueous rechargeable zinc-ion batteries (ARZBs) have been emerging as promising large-scale energy storage systems owing to their high energy densities, low manufacturing cost and intrinsic high safety. However, the direct application of industrial-scale Mn2O3 (MO) cathode exhibits poor electrochemical performance especially at high current rates. Herein, a highly reversible Mn-based cathode is developed from the industrial-scale MO by nitridation and following electrochemical oxidation, which triples the ion diffusion rate and greatly promotes the charge transfer. Notably, the cathode delivers a capacity of 161 mAh g-1 at a high current density of 10 A g-1, nearly-three times the capacity of pristine MO (60 mAh g-1). Impressive specific capacity (243.4 mAh g-1) is obtained without Mn2+ additive added in the electrolyte, much superior to the pristine MO (124.5 mAh g-1), suggesting its enhanced reaction kinetics and structural stability. In addition, it possesses an outstanding energy output of 368.4 Wh kg-1 at 387.8 W kg-1, which exceeds many of reported cathodes in ARZBs, providing new opportunities for the large-scale application of high-performance and low-cost ARZBs.

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Novel polyimide binder for achieving high-rate capability and long-term cycling stability of LiNi0.8Co0.1Mn0.1O2 cathode via constructing polar and micro-branched crosslinking network structure Yueming Xu, Yali Wang, Nanxi Dong, Chuanzhi Pu, Bingxue Liu, Guofeng Tian, Shengli Qi, Dezhen Wu 2023, 76(1): 19-31.  DOI: 10.1016/j.jechem.2022.09.008 Abstract ( 158 )   PDF (3544KB) ( 105 )   LiNi0.8Co0.1Mn0.1O2 (NCM811) material, as the promising cathode candidate for next-generation high-energy lithium-ion batteries, has gained considerable attention for extremely high theoretical capacity and low cost. Nevertheless, the intrinsic drawbacks of NCM811 such as unstable structure and inevitable interface side reaction result in severe capacity decay and thermal runaway. Herein, a novel polyimide (denoted as PI-OmDT) constructed with the highly polar and micro-branched crosslinking network is reported as a binder material for NCM811 cathode. The micro-branched crosslinking network is achieved by using 1,3,5-Tris(4-aminophenoxy) benzene (TAPOB) as a crosslinker via condensation reaction, which endows excellent mechanical properties and large free volume. Meanwhile, the massive polar carboxyl (-COOH) groups provide strong adhesion sites to active NCM811 particles. These functions of PI-OmDT binder collaboratively benefit to forming the mechanically robust and homogeneous coating layer with rapid Li+ diffusion on the surface of NCM811, significantly stabilizing the cathode structure, suppressing the detrimental interface side reaction and guaranteeing the shorter ion-diffusion and electron-transfer paths, consequently enhancing electrochemical performance. As compared to the NCM811 with PVDF binder, the NCM811 using PI-OmDT binder delivers a superior high-rate capacity (121.07 vs. 145.38 mAh g-1) at 5 C rate and maintains a higher capacity retention (80.38% vs. 91.6%) after 100 cycles at 2.5-4.3 V. Particularly, at the high-voltage conditions up to 4.5 and 4.7 V, the NCM811 with PI-OmDT binder still maintains the remarkable capacity retention of 88.86% and 72.5% after 100 cycles, respectively, paving the way for addressing the high-voltage operating stability of the NCM811 cathode. Moreover, the full-charged NCM811 cathode with PI-OmDT binder exhibits a significantly enhanced thermal stability, improving the safety performance of batteries. This work opens a new avenue for developing high-energy NCM811 based lithium-ion batteries with long cycle-life and superior safety performance using a novel and effective binder.

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Stable anode-free zinc-ion batteries enabled by alloy network-modulated zinc deposition interface Shiyin Xie, Yang Li, Liubing Dong 2023, 76(1): 32-40.  DOI: 10.1016/j.jechem.2022.08.040 Abstract ( 21 )   PDF (2334KB) ( 4 )   Newly-proposed anode-free zinc-ion batteries (ZIBs) are promising to remarkably enhance the energy density of ZIBs, but are restricted by the unfavorable zinc deposition interface that causes poor cycling stability. Herein, we report a Cu-Zn alloy network-modulated zinc deposition interface to achieve stable anode-free ZIBs. The alloy network can not only stabilize the zinc deposition interface by suppressing 2D diffusion and corrosion reactions but also enhance zinc plating/stripping kinetics by accelerating zinc desolvation and nucleation processes. Consequently, the alloy network-modulated zinc deposition interface realizes high coulombic efficiency of 99.2% and high stability. As proof, Zn//Zn symmetric cells with the alloy network-modulated zinc deposition interface present long operation lifetimes of 1900 h at 1 mA/cm2 and 1200 h at 5 mA/cm2, significantly superior to Zn//Zn symmetric cells with unmodified zinc deposition interface (whose operation lifetime is shorter than 50 h), and meanwhile, Zn3V3O8 cathode-based ZIBs with the alloy network-modified zinc anodes show notably enhanced rate capability and cycling performance than ZIBs with bare zinc anodes. As expected, the alloy network-modulated zinc deposition interface enables anode-free ZIBs with Zn3V3O8 cathodes to deliver superior cycling stability, better than most currently-reported anode-free ZIBs. This work provides new thinking in constructing high-performance anode-free ZIBs and promotes the development of ZIBs.

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A UV cross-linked gel polymer electrolyte enabling high-rate and high voltage window for quasi-solid-state supercapacitors Yuge Bai, Chao Yang, Boheng Yuan, Hongjie Li, Weimeng Chen, Haosen Yin, Bin Zhao, Fei Shen, Xiaogang Han 2023, 76(1): 41-50.  DOI: 10.1016/j.jechem.2022.09.015 Abstract ( 88 )   PDF (2580KB) ( 50 )   Serving as a promising alternative to liquid electrolyte in the application of portable and wearable devices, gel polymer electrolytes (GPEs) are expected to obtain more preferable properties rather than just be satisfied with the merits of high safety and deformability. Here, an easy-operated method is employed to fabricate cross-linked composite polymer membranes used for GPEs assisted by UV irradiation, in which N-doped carbon quantum dots (N-CQDs) and TiO2 are introduced as photocatalysts and additives to improve the performances of GPEs. Specifically, N-CQDs participate as a cross-linker to construct the inner porous structure, and TiO2 nanoparticles serve as a stabilizer to improve the electrochemical stability of GPEs under high voltage (3.5 V). The excellent thermal and mechanical stability of the membrane fabricated in this work guarantee the safety of the supercapacitors (SCs). This GPE based SC not only exhibits prominent rate performance (105% capacitance retention at the current density of 40 A g-1) and cyclic stability (85% at 1 A g-1 under 3.5 V after 20,000 cycles), but also displays remarkable energy density (42.88 Wh kg-1) with high power density (19.3 kW kg-1). Moreover, the superior rate and cycling performances of the as-prepared GPE based flexible SCs under flat and bending state confirm the feasibility of its application in flexible energy storage devices.

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Achieving stable K-storage performance of carbon sphere-confined Sb via electrolyte regulation Ningning Chen, Nailu Shen, Xiaoping Yi, Yinshuang Pang, Jing Zheng, Qingxue Lai, Yanyu Liang 2023, 76(1): 51-58.  DOI: 10.1016/j.jechem.2022.09.006 Abstract ( 105 )   PDF (2141KB) ( 68 )   Potassium-ion batteries (PIBs) have been considered as one of the most promising alternatives to lithium-ion batteries (LIBs) in view of their competitive energy density with significantly reduced product cost. Moreover, alloy-type materials are expected as a high-performance anode of PIBs thanks to their intrinsic chemical stability as well as high theoretical specific capacity. Unfortunately, the serious incompatibility between alloy-type active materials and electrolytes, especially for the formation of unstable solid-electrolyte interfacial (SEI) films, often leads to insufficient cycle life. Herein, the formation mechanism of SEI films in the K-storage systems based on carbon sphere confined Sb anode (Sb@CS) were investigated in commercially available electrolytes. Physical characterizations and theoretical calculation revealed that the solvents in the dilute electrolyte of 0.8 M KPF6/EC + DEC were excessively decomposed on the interface to generate unstable SEI and thus result in inferior K-storage stability. On the contrary, a salt-concentrated electrolyte (3 M KFSI/DME) can generate inorganic-dominated stable SEI due to the preferential decomposition of anions. As a result, the prepared Sb@CS in the matched 3 M KFSI/DME electrolyte delivered a high reversible capacity of 467.8 mA h g-1 after 100 cycles at 100 mA g-1, with a slow capacity decay of 0.19% per cycle from the 10th to the 100th cycle. These findings are of great significance for revealing the interfacial reaction between electrodes and electrolytes as well as improving the stability of Sb-based anode materials for PIBs.

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Ni-P-SBR composite-electroless-plating enables Si anode with high conductivity and elasticity for high performance Li-ion batteries application Yuxiao Wang, Jian Gou, Hongzhang Zhang, Xiaofei Yang, Huamin Zhang, Xianfeng Li 2023, 76(1): 59-66.  DOI: 10.1016/j.jechem.2022.09.004 Abstract ( 9 )   PDF (2117KB) ( 5 )   Silica-based anode is widely employed for high energy density Li-ion batteries owing to their high theoretical specific capacity (4200 mA h g-1). However, it is always accompanied by a huge volume expansion (300%) and shrinks during the lithiation/delithiation process, further leading to low cycle stability. Efforts to mitigate the adverse effects caused by volume expansion such as robust binder matrix, Core-shell structure, etc., inevitably affect the electronic conductivity within the electrode. Herein, a high conductivity and elasticity Si anode (Ni-P-SBR (styrene-butadiene rubber) @Si) was designed and fabricated via the Ni-P-SBR composite-electroless-plating process. In this design, the Si particles are surrounded by SBR polymer and Ni particles, where the SBR can adapt to the volume change and Ni particles can provide the electrode with high electronic conductivity. Therefore, the Ni-P-SBR@Si delivers a high initial capacity of 3470 mA h g-1and presents capacity retention of 49.4% within 200 cycles at 600 mA g-1. Additionally, a high capacity of 1153 mA h g-1 can be achieved at 2000 mA g-1 and can be cycled stably under bending conditions. This strategy provides feasible ideas to solve the key issues that limit the practical application of Si anodes.

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Regulated adsorption-diffusion and enhanced charge transfer in expanded graphite cohered with N, B bridge-doping carbon patches to boost K-ion storage Haiyan Wang, Haowen Du, Hucheng Zhang, Songjie Meng, Zhansheng Lu, Hao Jiang, Chunzhong Li, Jianji Wang 2023, 76(1): 67-74.  DOI: 10.1016/j.jechem.2022.09.009 Abstract ( 13 )   PDF (2638KB) ( 9 )   The great challenges are remained in constructing graphite-based anode with well built-in structures to accelerate kinetics and enhance stability in the advanced K-ion batteries (KIBs). Here, we firstly report the design of expanded graphite cohered by N, B bridge-doping carbon patches (NBEG) for efficient K-ion adsorption/diffusion and long-term durability. It is the B co-doping that plays a crucial role in maximizing doping-site utilization of N atoms, balancing the adsorption-diffusion kinetics, and promoting the charge transfer between NBEG and K ions. Especially, the robust lamellar structure, suitable interlayer distance, and rich active sites of the designed NBEG favor the rapid ion/electron transfer pathways and high K-ion storage capacity. Consequently, even at a low N, B doping concentration (4.36 at%, 2.07 at%), NBEG anode shows prominent electrochemical performance for KIBs, surpassing most of the advanced carbon-based anodes. Kinetic studies, density functional theory simulations, and in-situ Raman spectroscopy are further performed to reveal the K-ion storage mechanism and confirm the critical actions of co-doping B. This work offers the new methods for graphite-electrode design and the deeper insights into their energy storage mechanisms in KIBs.

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Peanut-chocolate-ball-inspired construction of the interface engineering between CdS and intergrown Cd: Boosting both the photocatalytic activity and photocorrosion resistance Wending Zhou, Feng Li, Xiangfei Yang, Wanliang Yang, Chun Wang, Rui Cao, Chengliang Zhou, Mengkui Tian 2023, 76(1): 75-89.  DOI: 10.1016/j.jechem.2022.09.013 Abstract ( 5 )   PDF (3719KB) ( 4 )   Interface engineering can improve the charge separation efficiency and inhibit photocorrosion is an emerging direction of developing more efficient and cost-effective photocatalytic systems. Herein, we report the sulfur-confined intimate CdS intergrown Cd (CdS/Cd) Ohmic junction (peanut-chocolate-ball like) for high-efficient H2 production with superior anti-photocorrosion ability, which was fabricated from in-situ photoreduction of CdS intergrown Cd2SO4(OH)2 (CdS/Cd2SO4(OH)2) prepared through a facile space-controlled-solvothermal method. The ratios of CdS/Cd can be effectively controlled by tunning that of CdS/Cd2SO4(OH)2 which were prepared by adjusting the volume of reaction liquid and the remaining space of the reactor. Experiments investigations and density functional theory (DFT) calculations reveal that the CdS intergrown Cd Ohmic junction interfaces (with appropriate content Cd intergrown on CdS (19.54 wt%)) are beneficial in facilitating the transfer of photogenerated electrons by constructing an interfacial electric field and forming sulfur-confined structures for preventing the positive holes (h+) oxidize the CdS. This contributes to a high photocatalytic H2 production activity of 95.40 μmol h-1 (about 32.3 times higher than bare CdS) and possesses outstanding photocatalytic stability over 205 h, much longer than most CdS-based photocatalysts previously reported. The interface engineering design inspired by the structure of peanut-chocolate-ball can greatly promote the future development of catalytic systems for wider application.

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MXene terminating groups O, -F or -OH, -F or O, -OH, -F, or O, -OH, -Cl? Tariq Bashir, Sara Adeeba Ismail, Jiaqi Wang, Wenhao Zhu, Jianqing Zhao, Lijun Gao 2023, 76(1): 90-104.  DOI: 10.1016/j.jechem.2022.08.032 Abstract ( 14 )   PDF (2801KB) ( 13 )   MXenes are a novel family of two-dimensional (2D) materials that are fast gaining popularity due to their versatile characteristics. The surfaces of these materials are often functionalized by negatively charged terminal groups, such as O, OH, and F during their synthesis, and it has been hypothesized that regulating the surface terminators enables to control the material characteristics. However, there is still a large gap between computational and experimental investigations regarding comprehending the surface functional groups. Surfaces with mixed terminations are consistently synthesized in experiments, although pure terminated surfaces are predicted by computational research. Here we summarized the nature of chemical bonding in transition metal carbide materials (MXenes) by 1H and 19F nuclear magnetic resonance (NMR), Raman, X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS)/scanning transmission electron microscopy (STEM), and thermogravimetric analysis-mass spectrometry (TGA-MS) characterizations. Previous literature reveals that O, -OH, -F, and -Cl are typical MXene surface terminators. However, recent comparative investigations on the valence band intensity distribution in MXenes reveal that the -OH cannot be considered an intrinsic termination species in MXenes. The surface terminals (O, -OH, -F, and -Cl) of several MXenes, particularly V2CTx and Ti3C2Tx, will be identified and quantified here. We have also discussed different etching approaches for the synthesis of MXene, the dependence of MXene conductivity on MXene terminating groups, and the emission of various gaseous products that evolved during its chemical transformations. This paper provides significance, especially in the field of energy conversion and storage materials, where the intercalation process is crucial.

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Coking and decoking chemistry for resource utilization of polycyclic aromatic hydrocarbons (PAHs) and low-carbon process Nan Wang, Li Wang, Yuchun Zhi, Jingfeng Han, Chengwei Zhang, Xinqiang Wu, Jinling Zhang, Linying Wang, Benhan Fan, Shutao Xu, Yijun Zheng, Shanfan Lin, Renan Wu, Yingxu Wei, Zhongmin Liu 2023, 76(1): 105-116.  DOI: 10.1016/j.jechem.2022.09.014 Abstract ( 23 )   PDF (1819KB) ( 10 )   Low-carbon process for resource utilization of polycyclic aromatic hydrocarbons (PAHs) in zeolite-catalyzed processes, geared to carbon neutrality-a prominent trend throughout human activities, has been bottlenecked by the lack of a complete mechanistic understanding of coking and decoking chemistry, involving the speciation and molecular evolution of PAHs, the plethora of which causes catalyst deactivation and forces regeneration, rendering significant CO2 emission. Herein, by exploiting the high-resolution matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance mass spectrometry (MALDI FT-ICR MS), we unveil the missing fingerprints of the mechanistic pathways for both formation and decomposition of cross-linked cage-passing PAHs for SAPO-34-catalyzed, industrially relevant methanol-to-olefins (MTO) as a model reaction. Notable is the molecule-resolved symmetrical signature: their speciation originates exclusively from the direct coupling of in-cage hydrocarbon pool (HCP) species, whereas water-promoted decomposition of cage-passing PAHs initiates with selective cracking of inter-cage local structures at 8-rings followed by deep aromatic steam reforming. Molecular deciphering the reversibly dynamic evolution trajectory (fate) of full-spectrum aromatic hydrocarbons and fulfilling the real-time quantitative carbon resource footprints advance the fundamental knowledge of deactivation and regeneration phenomena (decay and recovery motifs of autocatalysis) and disclose the underlying mechanisms of especially the chemistry of coking and decoking in zeolite catalysis. The positive yet divergent roles of water in these two processes are disentangled. These unprecedented insights ultimately lead us to a steam regeneration strategy with valuable CO and H2 as main products, negligible CO2 emission in steam reforming and full catalyst activity recovery, which further proves feasible in other important chemical processes, promising to be a sustainable and potent approach that contributes to carbon-neutral chemical industry.

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Hierarchically porous Co@N-doped carbon fiber assembled by MOF-derived hollow polyhedrons enables effective electronic/mass transport: An advanced 1D oxygen reduction catalyst for Zn-air battery Yifei Zhang, Quanfeng He, Zihao Chen, Yuqing Chi, Junwei Sun, Ding Yuan, Lixue Zhang 2023, 76(1): 117-126.  DOI: 10.1016/j.jechem.2022.09.012 Abstract ( 19 )   PDF (2302KB) ( 6 )   Developing advanced oxygen reduction reaction (ORR) electrocatalysts with rapid mass/electron transport as well as conducting relevant kinetics investigations is essential for energy technologies, but both still face ongoing challenges. Herein, a facile approach was reported for achieving the highly dispersed Co nanoparticles anchored hierarchically porous N-doped carbon fibers (Co@N-HPCFs), which were assembled by core-shell MOFs-derived hollow polyhedrons. Notably, the unique one-dimensional (1D) carbon fibers with hierarchical porosity can effectively improve the exposure of active sites and facilitate the electron transfer and mass transfer, resulting in the enhanced reaction kinetics. As a result, the ORR performance of the optimal Co@N-HPCF catalysts remarkably outperforms that of commercial Pt/C in alkaline solution, reaching a limited diffusion current density (J) of 5.85 mA cm-2 and a half-wave potential (E1/2) of 0.831 V. Particularly, the prepared Co@N-HPCF catalysts can be used as an excellent air-cathode for liquid/solid-state Zn-air batteries, exhibiting great potentiality in portable/wearable energy devices. Furthermore, the reaction kinetic during ORR process is deeply explored by finite element simulation, so as to intuitively grasp the kinetic control region, diffusion control region, and mixing control region of the ORR process, and accurately obtain the relevant kinetic parameters. This work offers an effective strategy and a reliable theoretical basis for the engineering of first-class ORR electrocatalysts with fast electronic/mass transport.

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Emerging catalytic materials for practical lithium-sulfur batteries Fangyi Shi, Lingling Zhai, Qingqing Liu, Jingya Yu, Shu Ping Lau, Bao Yu Xia, Zheng-Long Xu 2023, 76(1): 127-145.  DOI: 10.1016/j.jechem.2022.08.027 Abstract ( 22 )   PDF (4689KB) ( 6 )   High-energy lithium-sulfur batteries (LSBs) have experienced relentless development over the past decade with discernible improvements in electrochemical performance. However, a scrutinization of the cell operation conditions reveals a huge gap between the demands for practical batteries and those in the literature. Low sulfur loading, a high electrolyte/sulfur (E/S) ratio and excess anodes for lab-scale LSBs significantly offset their high-energy merit. To approach practical LSBs, high loading and lean electrolyte parameters are needed, which involve budding challenges of slow charge transfer, polysulfide precipitation and severe shuttle effects. To track these obstacles, the exploration of electrocatalysts to immobilize polysulfides and accelerate Li-S redox kinetics has been widely reported. Herein, this review aims to survey state-of-the-art catalytic materials for practical LSBs with emphasis on elucidating the correlation among catalyst design strategies, material structures and electrochemical performance. We also statistically evaluate the state-of-the-art catalyst-modified LSBs to identify the remaining discrepancy between the current advancements and the real-world requirements. In closing, we put forward our proposal for a catalytic material study to help realize practical LSBs.

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In situ characterizations of advanced electrode materials for sodium-ion batteries toward high electrochemical performances Xiu-Mei Lin, Xin-Tao Yang, Hao-Ning Chen, Yong-Liang Deng, Wen-Han Chen, Jin-Chao Dong, Yi-Min Wei, Jian-Feng Li 2023, 76(1): 146-164.  DOI: 10.1016/j.jechem.2022.09.016 Abstract ( 322 )   PDF (4801KB) ( 155 )   Energy storage is an ever-growing global concern due to increased energy needs and resource exhaustion. Sodium-ion batteries (SIBs) have called increasing attention and achieved substantial progress in recent years owing to the abundance and even distribution of Na resources in the crust, and the predicted low cost of the technique. Nevertheless, SIBs still face challenges like lower energy density and inferior cycling stability compared to mature lithium-ion batteries (LIBs). Enhancing the electrochemical performance of SIBs requires an in-deep and comprehensive understanding of the improvement strategies and the underlying reaction mechanism elucidated by in situ techniques. In this review, commonly applied in situ techniques, for instance, transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), and X-ray absorption near-edge structure (XANES), and their applications on the representative cathode and anode materials with selected samples are summarized. We discuss the merits and demerits of each type of material, strategies to enhance their electrochemical performance, and the applications of in situ characterizations of them during the de/sodiation process to reveal the underlying reaction mechanism for performance improvement. We aim to elucidate the composition/structure-performance relationship to provide guidelines for rational design and preparation of electrode materials toward high electrochemical performance.

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Interconnected and high cycling stability polypyrrole supercapacitors using cellulose nanocrystals and commonly used inorganic salts as dopants Zuxin Sun, Wim Thielemans 2023, 76(1): 165-174.  DOI: 10.1016/j.jechem.2022.09.024 Abstract ( 169 )   PDF (3769KB) ( 102 )   Polypyrrole (PPy) is wildly used as electrode material in supercapacitors due to its high conductivity, low cost, ease of handling, and ease of fabrication. However, limited capacitance and poor cycling stability hinder its practical application. After developing carboxylated cellulose nanocrystals (CNC-COO-) as immobile dopants for PPy to improve its cycling stability, we investigated the effect of different commonly used salts (KCl, NaCl, KBr, and NaClO4) as dopants during electrode fabrication by electropolymerization. The film’s capacitance increased from 160.6 to 183.4 F g-1 after adding a combination of KCl and NaClO4 into the electrodeposition electrolyte. More importantly, the porous and interconnected PPy/CNC-COO--Cl-(ClO4-)_0.5 electrode film exhibited an excellent capacitance of 125.0 F g-1 (0.78 F cm-2) at a high current density of 2.0 A g-1 (20 mA cm-2, allowing charging in less than 1 min), increasing almost 204% over PPy/CNC-COO- films. A symmetric PPy/CNC-COO--Cl-(ClO4-)_0.5 supercapacitor retained its full capacitance after 5000 cycles, and displayed a high energy density of 5.2 Wh kg-1 at a power density of 25.4 W kg-1 (34.5 μWh cm-2 at 1752.3 μW cm-2). These results reveal that the porous structure formed by doping with CNC-COO- and inorganic salts opens up more active reaction areas to store charges in PPy-based films as the stiff and ribbon-like CNC-COO- as permanent dopants improve the strength and stability of PPy-based films. Our demonstration provides a simple and practical way to deposit PPy based supercapacitors with high capacitance, fast charging, and excellent cycling stability.

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Polaron mobility modulation by bandgap engineering in black phase α-FAPbI3 Chunwei Wang, Zeyu Zhang, Zhuang Xiong, Xingyu Yue, Bo Zhang, Tingyuan Jia, Zhengzheng Liu, Juan Du, Yuxin Leng, Kuan Sun, Ruxin Li 2023, 76(1): 175-180.  DOI: 10.1016/j.jechem.2022.08.039 Abstract ( 17 )   PDF (1096KB) ( 7 )   Lead halide hybrid perovskites (LHP) have emerged as one of the most promising photovoltaic materials for their remarkable solar energy conversion ability. The transportation of the photoinduced carriers in LHP could screen the defect recombination with the help of the large polaron formation. However, the physical insight of the relationship between the superior optical-electronic performance of perovskite and its polaron dynamics related to the electron-lattice strong coupling induced by the substitution engineering is still lack of investigation. Here, the bandgap modulated thin films of α-FAPbI3 with different element substitution is investigated by the time resolved Terahertz spectroscopy. We find the polaron recombination dynamics could be prolonged in LHP with a relatively smaller bandgap, even though the formation of polaron will not be affected apparently. Intuitively, the large polaron mobility in (FAPbI3)0.95(MAPbI3)0.05 thin film is ∼30% larger than that in (FAPbI3)0.85(MAPbBr3)0.15. The larger mobility in (FAPbI3)0.95(MAPbI3)0.05 could be assigned to the slowing down of the carrier scattering time. Therefore, the physical origin of the higher carrier mobility in the (FAPbI3)0.95(MAPbI3)0.05 should be related with the lattice distortion and enhanced electron-phonon coupling induced by the substitution. In addition, (FAPbI3)0.95(MAPbI3)0.05 will lose fewer active carriers during the polaron cooling process than that in (FAPbI3)0.85(MAPbBr3)0.15, indicating lower thermal dissipation in (FAPbI3)0.95(MAPbI3)0.05. Our results suggest that besides the smaller bandgap, the higher polaron mobility improved by the substitution engineering in α-FAPbI3 can also be an important factor for the high PCE of the black phase α-FAPbI3 based solar cell devices.

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Constructing a 700 Wh kg-1-level rechargeable lithium-sulfur pouch cell Qian Cheng, Zi-Xian Chen, Xi-Yao Li, Li-Peng Hou, Chen-Xi Bi, Xue-Qiang Zhang, Jia-Qi Huang, Bo-Quan Li 2023, 76(1): 181-186.  DOI: 10.1016/j.jechem.2022.09.029 Abstract ( 73 )   PDF (986KB) ( 36 )   Lithium-sulfur (Li-S) batteries are considered as highly promising energy storage devices because of their ultrahigh theoretical energy density of 2600 Wh kg-1. The highest practical energy density of Li-S batteries reported at pouch cell level has exceeded 500 Wh kg-1, which significantly surpasses that of lithium-ion batteries. Herein, a 700 Wh kg-1-level Li-S pouch cell is successfully constructed. The pouch cell is designed at 6 Ah level with high-sulfur-loading cathodes of 7.4 mgS cm-2, limited anode excess (50 μm in thickness), and lean electrolyte (electrolyte to sulfur ratio of 1.7 gelectrolyte gS-1). Accordingly, an ultrahigh specific capacity of 1563 mA h g-1 is achieved with the addition of a redox comediator to afford a practical energy density of 695 Wh kg-1 based on the total mass of all components. The pouch cell can operate stably for three cycles and then failed due to rapidly increased polarization at the second discharge plateau. According to failure analysis, electrolyte exhaustion is suggested as the key limiting factor. This work achieves a significant breakthrough in constructing high-energy-density Li-S batteries and propels the development of Li-S batteries toward practical working conditions.

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MXene ink hosting zinc anode for high performance aqueous zinc metal batteries Jae Min Park, Milan Jana, Sang Ha Baek, Taehun Kang, Peixun Xiong, Jeong Hee Park, Jun Soo Kim, Ali Shayesteh Zeraati, Mikhail Shekhirev, Paul V. Braun, Yury Gogotsi, Ho Seok Park 2023, 76(1): 187-194.  DOI: 10.1016/j.jechem.2022.09.018 Abstract ( 18 )   PDF (2468KB) ( 8 )   Despite the safety, low cost, and high theoretical capacity (820 mA h g-1) of Zn metal anodes, the practical application of aqueous Zn metal batteries remains a critical challenge due to the Zn dendrite growth, corrosion, and hydrogen evolution reaction. Herein, we demonstrate the MXene ink hosting Zn metal anodes (MX@Zn) for high-performance and patternable Zn metal full batteries. The as-designed MX@Zn electrode is more facile and reversible than bare Zn and CC@Zn, as verified by better cyclic stability and lower overpotentials of symmetric cells with the plating capacity of 0.05 mA h cm-2 at 0.1 mA cm-2 and of 1 mA h cm-2 at 1 mA cm-2. The MX@Zn | MnO2 full cells deliver a high specific capacity of 281.9 mA h g-1, 91.5% of the theoretical capacity, achieving 50% capacity retention from 60 mA g-1 to 300 mA g-1 and 79.7% of initial capacity after 200 cycles. Moreover, the patterned devices based on the MX@Zn electrode achieve high energy and power densities of 348.57 Wh kg-1 and 1556 W kg-1, respectively, along with a capacity retention of 64% and Coulombic efficiency of 99% over 500 cycles. The high performance of MX@Zn is attributed to the high electrical conductivity and hydrophilicity of MXene and rapid ion diffusion through the 3D interconnected porous channels.

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High valence metals engineering strategies of Fe/Co/Ni-based catalysts for boosted OER electrocatalysis Lu Li, Xianjun Cao, Juanjuan Huo, Junpeng Qu, Weihua Chen, Chuntai Liu, Yufei Zhao, Hao Liu, Guoxiu Wang 2023, 76(1): 195-213.  DOI: 10.1016/j.jechem.2022.09.022 Abstract ( 27 )   PDF (4663KB) ( 20 )   Electrocatalysis for the oxygen evolution reactions (OER) has attracted much attention due to its important role in water splitting and rechargeable metal-air batteries. Therefore, designing highly efficient and low-cost catalysts for OER process is essential as the conventional catalysts still rely on precious metals. Transition metal-based compounds have been widely investigated as active OER catalysts, and renewed interest in the high valence metals engineered compounds has been achieved for superior catalytic activity and stability. However, an in-depth understanding of the construction strategies and induced effects for the high valence metals engineered catalysts is still lacking and desired. In this review, we have summarized the construction strategies of high valence metals as dopants or formed heterostructures with the iron/cobalt/nickel (Fe/Co/Ni)-based catalysts. Then the induced effects on Fe/Co/Ni-based catalysts by incorporating high valence metals, e.g., accelerating the surface reconstruction, forming amorphous structure, generating vacancies/defects, and acting as stabilizers, are highlighted. The impacts of high valence metals on OER performance are elucidated based on different elements, including molybdenum (Mo), tungsten (W), cerium (Ce), vanadium (V), chromium (Cr), manganese (Mn), niobium (Nb), zirconium (Zr). The correlations of construction strategies, induced effects, catalytic activity and OER reaction pathways are elaborated. Finally, the remaining challenges for further enhancements of OER performance induced by high valence metals are presented.

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Peripheral octamethyl-substituted nickel(II)-phthalocyanine-decorated carbon-nanotube electrodes for high-performance all-solid-state flexible symmetric supercapacitors Yu Wang, Minzhang Li, Rajendran Ramachandran, Haiquan Shan, Qian Chen, Anxin Luo, Fei Wang, Zong-Xiang Xu 2023, 76(1): 214-225.  DOI: 10.1016/j.jechem.2022.08.046 Abstract ( 36 )   PDF (4131KB) ( 15 )   Construction of advanced electrode materials with unique performance for supercapacitors (SCs) is essential to achieving high implementation in the commercial market. Here, we report a novel peripheral octamethyl-substituted nickel(II) phthalocyanine (NiMe2Pc)-based nanocomposite as the electrode material of all-solid-state SCs. The highly redox-active NiMe2Pc/carboxylated carbon nanotube (CNT-COOH) dendritic nanocomposite provides rapid electron/electrolyte ion-transport pathways and exhibits excellent structural stability, resulting in high-capacity activity and impressive cycling stability. The composite prepared with the optimized weight ratio of NiMe2Pc:CNT-COOH (6:10) showed the highest specific capacitance of 330.5 F g-1 at 0.25 A g-1. The constructed NiMe2Pc/CNT-COOH-based all-solid-state symmetric SC device showed excellent performance with a maximum energy density of 22.8 Wh kg-1 and outstanding cycling stability (111.6% retained after 35,000 cycles). Moreover, flexible carbon cloth significantly enhanced the energy density of the NiMe2Pc/CNT-COOH all-solid-state symmetric device to 52.1 Wh kg-1 with 95.4% capacitance retention after 35,000 cycles, and it could be applied to high-performance flexible electronics applications. These findings provide a novel strategy to design phthalocyanine-based electrode materials for next-generation flexible SC devices.

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Adjusting oxygen vacancies in perovskite LaCoO3 by electrochemical activation to enhance the hydrogen evolution reaction activity in alkaline condition Chengrong Wu, Yan Sun, Xiaojian Wen, Jia-Ye Zhang, Liang Qiao, Jun Cheng, Kelvin H.L. Zhang 2023, 76(1): 226-232.  DOI: 10.1016/j.jechem.2022.08.035 Abstract ( 20 )   PDF (1397KB) ( 5 )   Developing highly-active, earth-abundant non-precious-metal catalysts for hydrogen evolution reaction (HER) in alkaline solution would be beneficial to sustainable energy storage. Perovskite oxides are generally regarded as low-active HER catalysts, due to their inapposite hydrogen adsorption and water dissociation. Here, we report a detailed study on perovskite LaCoO3 epitaxial thin films as a model catalyst to significantly enhance the HER performance via an electrochemical activation process. As a result, the overpotential for the activation films to achieve a current density of 0.36 mA/cm2 is 238 mV, reduced by more than 200 mV in comparison with that of original samples. Structural characterization revealed the activation process dramatically increases the concentration of oxygen vacancies (Vo) on the surface of LaCoO3. We established the relationship between the electronic structure induced by VO and the enhanced HER activity. Further theoretical calculations revealed that the VO optimizes the hydrogen adsorption and dissociation of water on the surface of LaCoO3 thin films, thus improving the HER catalytic activity. This work may promote a deepened understanding of perovskite oxides for HER mechanism by Vo adjusting and a new avenue for designing highly active electrochemical catalysts in alkaline solution.

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20 µm Li metal modified with phosphate rich polymer-inorganic interphase applied in commercial carbonate electrolyte Lin Lin, Wei Lu, Feipeng Zhao, Siru Chen, Jia Liu, Haiming Xie, Yulong Liu 2023, 76(1): 233-238.  DOI: 10.1016/j.jechem.2022.09.017 Abstract ( 18 )   PDF (2074KB) ( 8 )   Li metal batteries are supposed to reach real application in order to fulfill the high-energy density requirement of energy storage system. Unfortunately, the commonly used carbonate electrolyte react with pristine Li, which result in short lifetime of lithium metal battery. To alleviate the side reactions of Li metal with liquid electrolyte, here we propose a phosphate rich polymer-inorganic layer as an interphase. Due to the inert properties of lithium phosphate derived from LiPO2F2 and poly-ether, the side-reaction of carbonate solvent are prevented. As a result, lithium metal anode sustains for 800 cycles in symmetrical cell test under 1 mA cm-2. Even under strict condition (20 µm Li, capacity ratio N/P = 2.3, electrolyte/active material = 3 µL mg-1), coin cell test still runs stable for 150 cycles with high Coulombic efficiency. Furthermore, both LiFePO4 and LiNi0.8Co0.1Mn0.1O2 pouch cell under 5 µL mA-1 h-1 condition also exhibit good stability at 0.5 C and 2 C rate. With this approach, high-energy and high-power Li metal batteries are approaching to real application in the near future.

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Efficient light-driven reductive amination of furfural to furfurylamine over ruthenium-cluster catalyst Zhen Xue, Shasha Wu, Yujing Fu, Lan Luo, Min Li, Zhenhua Li, Mingfei Shao, Lirong Zheng, Ming Xu, Haohong Duan 2023, 76(1): 239-248.  DOI: 10.1016/j.jechem.2022.09.027 Abstract ( 17 )   PDF (2429KB) ( 6 )   Selective reductive amination of carbonyl compounds with high activity is very essential for the chemical and pharmaceutical industry, but scarcely successful paradigm was reported via efficient photocatalytic reactions. Herein, the ultrasmall Ru nanoclusters (∼0.9 nm) were successfully fabricated over P25 support with positive charged Ruδ+ species at the interface. A new route was developed to achieve the furfural (FAL) to furfurylamine (FAM) by coupling the light-driven reductive amination and hydrogen transfer of ethanol over this type catalyst. Strikingly, the photocatalytic activity and selectivity are strongly dependent on the particle size and electronic structure of Ruthenium. The Ruδ+ species at the interface promote the formation of active imine intermediates; moreover, the Ru nanoclusters facilitate the separation efficiency of electrons and holes as well as accelerate the further hydrogenation of imine intermediates to product primary amines. In contrast Ru particles in larger nanometer size facilitate the formation of the furfuryl alcohol and excessive hydrogenation products. In addition, the coupling byproducts can be effectively inhibited via the construction of sub-nanocluster. This study offers a new path to produce the primary amines from biomass-derived carbonyl compounds over hybrid semiconductor/metal-clusters photocatalyst via light-driven tandem catalytic process.

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Amine-functionalized hierarchically porous carbon supported Pd nanocatalysts for highly efficient H2 generation from formic acid with fast-diffusion channels Xianzhao Shao, Xinyi Miao, Fengwu Tian, Miaomiao Bai, Xiaosha Guo, Wei Wang, Zuoping Zhao, Xiaohui Ji, Miyi Li, Fangan Deng 2023, 76(1): 249-258.  DOI: 10.1016/j.jechem.2022.10.002 Abstract ( 7 )   PDF (3320KB) ( 4 )   Formic acid (FA) has come to be considered a potential candidate for hydrogen storage, and the development of efficient catalysts for H2 releasing is crucial for realizing the sustainable process from FA. Herein, we have developed the ultrafine Pd nanoparticle (NPs) with amine-functionalized carbon as a support, which was found to show an excellent catalytic activity in H2 generation from FA dehydrogenation. The synergetic mechanism between amine-group and Pd active site was demonstrated to facilitate H2 generation by β-hydride elimination. Moreover, the texture of support for Pd NPs also plays an important role in determining the reactivity of FA, since the diffusion of gaseous products makes the kinetics of diffusion as a challenge in this high performance Pd catalysts. As a result, the as-prepared Pd/NH2-TPC catalyst with the small sized Pd nanoparticles and the hierarchically porous structures shows a turnover of frequency (TOF) value of 4312 h-1 for the additive-free FA dehydrogenation at room temperature, which is comparable to the most promising heterogeneous catalysts. Our results demonstrated that the intrinsic catalytic activities of active site as well as the porous structure of support are both important factors in determining catalytic performances in H2 generation from FA dehydrogenation, which is also helpful to develop high-activity catalysts for other advanced gas-liquid-solid reactions systems.

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Enhancing the stability of planar perovskite solar cells by green and inexpensive cellulose acetate butyrate Bo Xiao, Yongxin Qian, Xin Li, Yang Tao, Zijun Yi, Qinghui Jiang, Yubo Luo, Junyou Yang 2023, 76(1): 259-265.  DOI: 10.1016/j.jechem.2022.09.039 Abstract ( 10 )   PDF (1924KB) ( 5 )   Although the efficiency of organic-inorganic hybrid halide perovskite solar cells has been improved rapidly, the intrinsic instability of perovskite materials restricts their commercial application. Here, an eco-friendly and low-cost organic polymer, cellulose acetate butyrate (CAB), was introduced to the grain boundaries and surfaces of perovskite, resulting in a high-quality and low-defect perovskite film with a nearly tenfold improvement in carrier lifetime. More importantly, the CAB-treated perovskite films have a well-matched energy level with the charge transport layers, thus suppressing carrier nonradiative recombination and carrier accumulation. As a result, the optimized CAB-based device achieved a champion efficiency of 21.5% compared to the control device (18.2%). Since the ester group in CAB bonds with Pb in perovskite, and the H and O in the hydroxyl group bond with the I and organic cations in perovskite, respectively, it will contribute to superior stability under heat, high humidity, and light soaking conditions. After aging under 35% humidity (relative humidity, RH) for 3300 h, the optimized device can still maintain more than 90% of the initial efficiency; it can also retain more than 90% of the initial efficiency after aging at 65 °C, 65% RH, or light (AM 1.5G) for 500 h. This simple optimization strategy for perovskite stability could facilitate the commercial application of perovskite solar cells.

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Enabling structural and interfacial stability of 5 V spinel LiNi0.5Mn1.5O4 cathode by a coherent interface Min Xu, Ming Yang, Minfeng Chen, Lanhui Gu, Linshan Luo, Songyan Chen, Jizhang Chen, Bo Liu, Xiang Han 2023, 76(1): 266-276.  DOI: 10.1016/j.jechem.2022.09.021 Abstract ( 16 )   PDF (2949KB) ( 5 )   Spinel LiNi0.5Mn1.5O4 (LNMO), a 5 V class high voltage cathode, has been regarded as an attractive candidate to further improve the energy density of lithium-ion battery. The issue simultaneously enabling side stability and maintaining high interfacial kinetics, however, has not yet been resolved. Herein, we design a coherent Li1.3Al0.3Ti1.7(PO)4 (LATP) layer that is crystally connected to the spinel LNMO host lattices, which offers fast lithium ions transportation as well as enhances the mechanical stability that prevents the particle fracture. Furthermore, the inactive Li3BO3 (LBO) coating layer inhibits the corrosion of transition metals and continuous side reactions. Consequently, the coherent-engineered LNMO-LATP-LBO cathode material exhibits superior electrochemical cycling stability in a window of 3.0-5.0 V, for example a high-capacity retention that is 89.7% after 500 cycles at 200 mA g-1 obtained and enhanced rate performance (85.1 mA h g-1 at 800 mA g-1) when tested with a LiPF6-based carbonate electrolyte. Our work presents a new approach of engineering 5 V class spinel oxide cathode that combines interfacial coherent crystal lattice design and surface coating.

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Bottom-up holistic carrier management strategy induced synergistically by multiple chemical bonds to minimize energy losses for efficient and stable perovskite solar cells Baibai Liu, Ru Li, Qixin Zhuang, Xuemeng Yu, Shaokuan Gong, Dongmei He, Qian Zhou, Hua Yang, Xihan Chen, Shirong Lu, Zong-Xiang Xu, Zhigang Zang, Jiangzhao Chen 2023, 76(1): 277-287.  DOI: 10.1016/j.jechem.2022.09.037 Abstract ( 6 )   PDF (3253KB) ( 3 )   The defects from electron transport layer, perovskite layer and their interface would result in carrier nonradiative recombination losses. Poor buried interfacial contact is detrimental to charge extraction and device stability. Here, we report a bottom-up holistic carrier management strategy induced synergistically by multiple chemical bonds to minimize bulk and interfacial energy losses for high-performance perovskite photovoltaics. 4-trifluoromethyl-benzamidine hydrochloride (TBHCl) containing -CF3, amidine cation and Cl- is in advance incorporated into SnO2 colloid solution to realize bottom-up modification. The synergistic effect of multiple functional groups and multiple-bond-induced chemical interaction are revealed theoretically and experimentally. F and Cl- can passivate oxygen vacancy and/or undercoordinated Sn4+ defects by coordinating with Sn4+. The F can suppress cation migration and modulate crystallization via hydrogen bond with FA+, and can passivate lead defects by coordinating with Pb2+. The -NH2-CNH2+ and Cl- can passivate cation and anion vacancy defects through ionic bonds with perovskites, respectively. Through TBHCl modification, the suppression of agglomeration of SnO2 nanoparticles, bulk and interfacial defect passivation, and release of tensile strains of perovskite films are demonstrated, which resulted in a PCE enhancement from 21.28% to 23.40% and improved stability. With post-treatment, the efficiency is further improved to 23.63%.

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Improved interfacial adhesion for stable flexible inverted perovskite solar cells Jie Dou, Qizhen Song, Yue Ma, Hao Wang, Guizhou Yuan, Xueyuan Wei, Xiuxiu Niu, Sai Ma, Xiaoyan Yang, Jing Dou, Shaocheng Liu, Huanping Zhou, Cheng Zhu, Yihua Chen, Yujing Li, Yang Bai, Qi Chen 2023, 76(1): 288-294.  DOI: 10.1016/j.jechem.2022.09.044 Abstract ( 25 )   PDF (1590KB) ( 13 )   Flexible perovskite solar cells have attracted widespread attention due to their unique advantages in lightweight, high flexibility, and easy deformation, which are suitable for portable electronics. However, the inverted (p-i-n) structured devices suffer from poor stability largely due to the low adhesion at the brittle interface (the hole transport layer/perovskite). Herein, zeolitic imidazolate framework-67 (ZIF-67) is applied to inverted structured cells to optimize the interface and prolong the device lifetime. As a result, the flexible devices based on ZIF-67 obtain the champion power conversion efficiency of 20.16%. Over 1000 h under continuous light irradiation, the device retains 96% and 80% of its original efficiency without and with bias, respectively. Notably, devices show mechanical endurance with over 78% efficiency retention after 10,000 cycles of consecutive bending cycles (R = 6 mm). The introduction of ZIF-67 suppresses the cracking in device bending, which results in improved environmental stability and bending durability.

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Recent advances in titanium carbide MXene-based nanotextures with influential effect of synthesis parameters for solar CO2 reduction and H2 production: A critical review Muhammad Tahir, Azmat Ali Khan, Sehar Tasleem, Rehan Mansoor, Areen Sherryna, Beenish Tahir 2023, 76(1): 295-331.  DOI: 10.1016/j.jechem.2022.09.046 Abstract ( 64 )   PDF (5893KB) ( 22 )   Photocatalytic solar to energy conversion is considered an attractive approach for overcoming energy crises and environmental concerns. Recently, titanium carbide (Ti3C2) MXenes have been recognized as promising cocatalysts based on their metallic conductivity, excessive active reaction sites, and enlarged surface area. The current review focuses on the properties and applications of Ti3C2 MXenes useful in the field of photocatalysis. More specifically, surface modification of Ti3C2 MXenes by varying synthesis parameters to get pure materials and also composites with the role of functional groups towards solar energy conversion applications is highlighted in this review. The effect of etching and oxidizing pathways to get an efficient cocatalyst has been discussed in detail. Considering the significant effect of parameters, optimum synthesis conditions such as etchant type, concentration, time and type of intercalant in both the Ti3C2 synthesis approaches for improved photoactivity are discussed. Additionally, the surface modification of Ti3C2 through oxidation for TiO2 growth on its surface is deliberated with a detailed discussion on etchant type, concentration, etching time, and environmental factors. The optimum oxidation condition, including temperature, time, and environment for thermal treatment of Ti3C2, were also included. Lastly, the review summarizes the conclusion and future perspectives for solar energy conversion applications.

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Cocoon-shaped P3-type K0.5Mn0.7Ni0.3O2 as an advanced cathode material for potassium-ion batteries Liping Duan, Jianzhi Xu, Yifan Xu, Ruiqi Tian, Yingying Sun, Chuannan Zhu, Xiangyin Mo, Xiaosi Zhou 2023, 76(1): 332-338.  DOI: 10.1016/j.jechem.2022.10.006 Abstract ( 20 )   PDF (1635KB) ( 7 )   Potassium ion batteries (PIBs) are emerging as potential next-generation energy storage systems on account of their low cost and high theoretical energy density. Nevertheless, they also face challenges of low specific capacity and suboptimal cycling stability. Herein, we synthesize a cocoon-like P3-type K0.5Mn0.7Ni0.3O2 (KMNO) cathode material by a self-template method. The KMNO cocoons possess a hierarchical layered architecture composed of nanoparticle stacking, which can accelerate the transport kinetics of potassium ions, mitigate the stress caused by K+ intercalation and deintercalation, and improve structural stability. In addition, Ni can not only alleviate the Jahn-Teller distortion and suppress the phase transition to stabilize the structure, but also act as an electrochemically active element, providing the capacity of two electrons from Ni2+ to Ni4+. Combining the advantages of structure and nickel substitution, the P3-type KMNO cocoons are used for electrochemical performance testing of PIB cathodes, delivering an excellent rate capability of 57.1 mA h g-1 at 500 mA g-1 and a remarkable cycling stability of 77.0% over 300 cycles at 100 mA g-1. Impressively, the KMNO cocoons//pitch-derived soft carbon assembled full battery exhibits superior electrochemical performance with a reversible capacity of 79.7 mA h g-1 at 50 mA g-1. Moreover, ex-situ XRD also further reveals a solid solution phase reaction with a volume change of only 1.46%. This work furnishes a suitable approach to fabricating high-performance layered oxide cathodes for PIBs with outstanding cycling stability and rate capability.

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Tuning Li nucleation and growth via oxygen vacancy-enriched 3D flexible self-supporting protection layer of P-Mn3O4-x for advanced lithium-sulfur batteries Tao Liu, Jing Li, Hongtao Cui, Yuanyuan Liu, Kaihua Liu, Huiying Wei, Meiri Wang 2023, 76(1): 339-348.  DOI: 10.1016/j.jechem.2022.10.012 Abstract ( 27 )   PDF (2530KB) ( 11 )   Lithium sulfur batteries have attracted much attention due to their high theoretical specific energy and environmental friendliness. However, the practical application is severely plagued by the cycling life issues resulting from the uncontrollable generation and growth of Li dendrites. Herein, an innovative 3D flexible self-supporting Li anode protection layer of P-Mn3O4-x is constructed via a facile solvothermal method followed by an annealing process. Benefiting from the rich oxygen vacancies coupled with the 3D flexible self-supporting skeleton, abundant lithiophilic sites and high ionic conductivity are obtained, which succeed in guiding Li+ homogeneous adsorption and redistribution, accelerating Li+ diffusion rate, inducing Li+ uniform deposition and nucleation. DFT calculations and experimental results conclusively demonstrate such a protection mechanism. Meanwhile, the effective anchoring and catalytic nature of polar P-Mn3O4-x can also be applied as an immobilization-diffusion-conversion host to improve polysulfides redox. Taking advantage of these merits, super-stable functions for Li symmetric cell matched with P-Mn3O4-x layer are achieved, which exhibits an ultralong lifespan of >5000 h with an ultralow overpotential of 20 mV, far lower than that of bare Li symmetric cell (overpotential of 800 mV only after 250 h) at high current densities of 5 mA cm-2 and high plating/stripping capacity of 10 mA h cm-2. Even in Li|P-Mn3O4-x||S full cell at 1 C, a high initial discharge specific capacity of 843.1 mA h g-1 is still delivered with ultralow capacity fading rate of 0.07% per cycle after 250 cycles, further confirming the synergistic regulation of P-Mn3O4-x for Li nucleation behavior. This work illustrates a sufficient guarantee of 3D protection layer coupled with oxygen vacancies in guiding Li diffusion and nucleation behavior and provides new guidance for promoting the development of advanced Li-S batteries.

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Confining SnS2@N, S codoped carbon in core-shell beads of necklace-like fibers towards ultrastable anode for flexible potassium-ion battery Jiaqi Si, Xueya Liu, Zili Wang, Sen Zhang, Chao Deng 2023, 76(1): 349-358.  DOI: 10.1016/j.jechem.2022.09.048 Abstract ( 4 )   PDF (2954KB) ( 1 )   Tin sulfide (SnS2) with high theoretical capacity and layered structure is a promising anode candidate for potassium-ion batteries (PIBs). However, the sluggish kinetics, huge volume expansion and polysulfide intermediates dissolution restrict its development. To address these issues, a necklace-like hybrid fiber with core-shell beads is designed to achieve the high-performance anode for PIBs. The cores of the beads are assembly by SnS2 nanocrystals dotted in N, S codoped carbon (NSC) matrix. Then they are encapsulated by NSC based shell and form the core-shell structured beads internal the hybrid fiber (CSN fiber). The carbon matrix of SnS2@NSC CSN fiber gives fast ion/electron pathways and facilitates to decrease particle aggregation. Meanwhile, N, S codpants favor to trap the polysulfides intermediates and alleviate the sulfur loss during cycling. Moreover, the voids internal the beads further provide the high accommodation to volume change. Taken all above advantages, the SnS2@NSC CSN fiber achieves the excellent high rate capability and ultrastable cycling property, which obtains a low capacity decay rate of 0.013% after 2000 cycles at 2 A g-1. Moreover, its good mechanical characteristics ensure the fabrication of the flexible PIB full cell, which achieves the high pliability, superior power/energy density and high reliability in diverse working conditions. Therefore, this work not only gives a new clue to design the high-performance electrode for potassium storage, but also propels the applications of PIBs for diverse electronics.

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Regulated electronic structure and improved electrocatalytic performances of S-doped FeWO4 for rechargeable zinc-air batteries Huan Wang, Li Xu, Daijie Deng, Xiaozhi Liu, Henan Li, Dong Su 2023, 76(1): 359-367.  DOI: 10.1016/j.jechem.2022.09.023 Abstract ( 10 )   PDF (3148KB) ( 4 )   The exploration of active and long-lived oxygen reduction reaction (ORR) catalysts for the commercialization of zinc-air batteries are of immense significance but challenging. Herein, the sulfur doped FeWO4 embedded in the multi-dimensional nitrogen-doped carbon structure (S-FeWO4/NC) was successfully synthesized. The doped S atoms optimized the charge distribution in FeWO4 and enhanced the intrinsic activity. At the same time, S doping accelerated the formation of reaction intermediates during the adsorption reduction of O2 on the surface of S-FeWO4/NC. Accordingly, the S-FeWO4/NC catalyst showed more positive half-wave potential (0.85 V) and better stability than that of the FeWO4/NC catalyst. Furthermore, the S-FeWO4/NC-based zinc-air battery exhibited considerable power density of 150.3 mW cm-2, high specific capacity of 912.7 mA h g-1, and prominent cycle stability up to 220 h. This work provides an assistance to the development of cheap and efficient tungsten-based oxygen reduction catalysts and the promotion of its application in the zinc-air battery.

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Dual-conductive metal-organic framework@MXene heterogeneity stabilizes lithium-ion storage Lanju Sun, Honglei Wang, Shengliang Zhai, Jikai Sun, Xu Fang, Hongyan Yang, Dong Zhai, Chengcheng Liu, Wei-Qiao Deng, Hao Wu 2023, 76(1): 368-376.  DOI: 10.1016/j.jechem.2022.09.035 Abstract ( 13 )   PDF (1867KB) ( 8 )   Although a few pristine metal-organic frameworks (MOFs) of graphene analogue topology exhibit high intrinsic electrical conductivity, their use in lithium-ion batteries (LIBs) is still hampered by unfavorable Li+ adsorption energy (ΔEa). In this paper, an electroconductive ferrocene-based MOF@MXene heterostructure is built to provide stable anodes for Li+ storage. Charge density difference and planar average potential charge density show substantial redistribution of charges at the interfaces, transferring from MXene to MOF layers. Moreover, density functional theory (DFT) calculations reveal that the interaction between MXene and MOF significantly increases the ΔEa. As a result, the heterostructure anode exhibits high capacities and outstanding cycling stability with a capacity retention of 80% after 5000 cycles at 5 A g-1, outperforming mono-component MXene and MOF. Furthermore, the heterostructure anode is built into a full cell with a commercial NCM 532 cathode, delivering a high energy density of 611 Wh kg-1 and power density of 7600 W kg-1. The developed conductive MOF@MXene heterogeneity for improved LIB offers valuable insights into the design of advanced electrode materials for energy storage.

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The action mechanisms and structures designs of F-containing functional materials for high performance oxygen electrocatalysis Gang Wang, Shuwei Jia, Hongjing Gao, Yewen Shui, Jie Fan, Yixia Zhao, Lei Li, Weimin Kang, Nanping Deng, Bowen Cheng 2023, 76(1): 377-397.  DOI: 10.1016/j.jechem.2022.09.038 Abstract ( 7 )   PDF (4808KB) ( 4 )   Non-renewable fossil fuels have led to serious problems such as global warming, environmental pollution, etc. Oxygen electrocatalysis including oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays a central role in clean energy conversion, enabling a number of sustainable processes for future air battery technologies. Fluorine, as the most electronegative element (4.0) not only can induce more efficient regulation for the electronic structure, but also can bring more abundant defects and other novel effects in materials selection and preparation for favorable catalysis with respect to the other non-metal elements. However, an individual and comprehensive overview of fluorine-containing functional materials for oxygen electrocatalysis field is still blank. Therefore, it is very meaningful to review the recent progresses of fluorine-containing oxygen electrocatalysts. In this review, we first systematically summarize the controllable preparation methods and their possible development directions based on fluorine-containing materials from four preparation methods. Due to the strong electron-withdrawing properties of fluorine, its control of the electronic structure can effectively enhance the oxygen electrocatalytic activity of the materials. In addition, the catalytic enhancement effect of fluorine on carbon-based materials also includes the prevent oxidation and the layer peeling, and realizes the precise atomic control. And the catalytic improvement mechanism of fluorine containing metal-based compounds also includes the hydration of metal site, the crystal transformation, and the oxygen vacancy induction. Then, based on their various dimensions (0D-3D), we also have summarized the advantages of different morphologies on oxygen electrocatalytic performances. Finally, the prospects and possible future researching direction of F-containing oxygen electrocatalysts are presented (e.g., novel pathways, advanced methods for measurement and simulation, field assistance and multi-functions). The review is considered valuable and helpful in exploring the novel designs and mechanism analyses of advanced fluorine-containing electrocatalysts.

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A surfactant-modified composite separator for high safe lithium ion battery Botao Yuan, Niandong He, Yifang Liang, Liwei Dong, Jipeng Liu, Jiecai Han, Weidong He, Yuanpeng Liu 2023, 76(1): 398-403.  DOI: 10.1016/j.jechem.2022.10.013 Abstract ( 19 )   PDF (1234KB) ( 15 )   Separators have been gaining increasing attention to improve the performance of lithium ion batteries (LIBs), especially for high safe and long cycle life. However, commercial polyolefin separators still face the problems of rapid capacity decay and safety issues due to the poor wettability with electrolytes and low thermal stability. Herein, a novel composite separator is proposed by introducing a surfactant of sodium dodecyl thiosulfate (SDS) into the polytetrafluoroethylene (PTFE) substrate with the binder of polyacrylic acid (PAA) through the suction filtration method. The introduction of PAA/SDS enhances the adsorption energy between PTFE substrate and electrolyte through density functional theory calculations, which improves wettability and electrolyte uptake of the separator significantly. The as-achieved composite separator enables the LIBs to own high Li+ conductivity (0.64 × 10-3 S cm-1) and Li+ transference number (0.63), further leading to a high capacity retention of 93.50% after 500 cycles at 1 C. In addition, the uniform and smooth surface morphology of Li metal employed the composite separator after cycling indicates that the lithium dendrites can be successfully inhibited. This work indicates a promising route for the preparation of a novel composite separator for high safe LIBs.

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Semi-supervised estimation of capacity degradation for lithium ion batteries with electrochemical impedance spectroscopy Rui Xiong, Jinpeng Tian, Weixiang Shen, Jiahuan Lu, Fengchun Sun 2023, 76(1): 404-413.  DOI: 10.1016/j.jechem.2022.09.045 Abstract ( 14 )   PDF (1596KB) ( 6 )   Machine learning-based methods have emerged as a promising solution to accurate battery capacity estimation for battery management systems. However, they are generally developed in a supervised manner which requires a considerable number of input features and corresponding capacities, leading to prohibitive costs and efforts for data collection. In response to this issue, this study proposes a convolutional neural network (CNN) based method to perform end-to-end capacity estimation by taking only raw impedance spectra as input. More importantly, an input reconstruction module is devised to effectively exploit impedance spectra without corresponding capacities in the training process, thereby significantly alleviating the cost of collecting training data. Two large battery degradation datasets encompassing over 4700 impedance spectra are developed to validate the proposed method. The results show that accurate capacity estimation can be achieved when substantial training samples with measured capacities are given. However, the estimation performance of supervised machine learning algorithms sharply deteriorates when fewer samples with measured capacities are available. In this case, the proposed method outperforms supervised benchmarks and can reduce the root mean square error by up to 50.66%. A further validation under different current rates and states of charge confirms the effectiveness of the proposed method. Our method provides a flexible approach to take advantage of unlabelled samples for developing data-driven models and is promising to be generalised to other battery management tasks.

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Effects of electron- and hole-current hysteresis on trap characterization in organo-inorganic halide perovskite Fan Wu, Sally Mabrouk, Miaomiao Han, Yanhua Tong, Tiansheng Zhang, Yuchen Zhang, Raja Sekhar Bobba, Quinn Qiao 2023, 76(1): 414-420.  DOI: 10.1016/j.jechem.2022.10.011 Abstract ( 3 )   PDF (895KB) ( 3 )   Charge trap density and carrier mobility of perovskite materials are the critical properties of perovskite solar cells. The space charge limited current (SCLC) method, which measures a dark current-voltage (I-V) curve of a single-carrier device has found extensive use for studying the trap density and charge carrier mobility in perovskite materials. Herein, it was found that the electron- and hole-current in organo-lead perovskite-based single-carrier device undergoes significant hysteresis under forward and reverse scanning due to the mobile ions. In addition, it was also observed that measuring history has a detrimental effect on hysteresis resulting in possible overestimation or underestimation of the extracted electrical values from the SCLC measurement. In the forward/reverse scanning process, the mobile ionic defects enhance/shield the charge in the traps due to ionic charging/discharging, thereby increasing/reducing the interface barrier and net charge in the I-V scanning, which in turn affects the determination of transport properties of the carrier. These results raise quite a few doubts over the direct application of classical SCLC measurements for the accurate characterization of intrinsic transport properties of the mixed ionic-electronic perovskite.

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One-pot synthesis of 2,5-bis(hydroxymethyl)furan from biomass derived 5-(chloromethyl)furfural in high yield Binglin Chen, Yunchao Feng, Sen Ma, Weizhen Xie, Guihua Yan, Zheng Li, Jonathan Sperry, Shuliang Yang, Xing Tang, Yong Sun, Lu Lin, Xianhai Zeng 2023, 76(1): 421-428.  DOI: 10.1016/j.jechem.2022.10.005 Abstract ( 15 )   PDF (1839KB) ( 9 )   5-(Chloromethyl)furfural (CMF), as a new platform molecular, has become a hot topic in the field of biorefinery. Herein, the one-pot conversion of CMF to 2,5-bis(hydroxymethyl)furan (BHMF) in the water phase was demonstrated for the first time. A 91% BHMF yield was obtained over Ru/CuOx catalyst, and BHMF was mainly produced by the consecutive hydrolysis and hydrogenation of CMF with 5-hydroxymethylfurfural (HMF) as an intermediate. Kinetic studies revealed that the conversion of HMF to BHMF was the rate-determining step. Remarkably, the characterizations and density functional theory (DFT) calculations further revealed the lower electron density of Ru NPs in Ru/CuOx catalyst, resulting in a larger adsorption energy and a smaller free energy difference for the formation of alcohols. The present findings offered a new pathway for biomass-derived diol production through CMF as a potential source.

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Tracking the phase transformation and microstructural evolution of Sn anode using operando synchrotron X-ray energy-dispersive diffraction and X-ray tomography Kang Dong, Fu Sun, André Hilger, Paul H. Kamm, Markus Osenberg, Francisco García-Moreno, Ingo Manke 2023, 76(1): 429-437.  DOI: 10.1016/j.jechem.2022.10.014 Abstract ( 5 )   PDF (1314KB) ( 2 )   Tin (Sn) holds great promise as an anode material for next-generation lithium (Li) ion batteries but suffers from massive volume change and poor cycling performance. To clarify the dynamic chemical and microstructural evolution of Sn anode during lithiation and delithiation, synchrotron X-ray energy-dispersive diffraction and X-ray tomography are simultaneously employed during Li/Sn cell operation. The intermediate Li-Sn alloy phases during de/lithiation are identified, and their dynamic phase transformation is unraveled which is further correlated with the volume variation of the Sn at particle- and electrode-level. Moreover, we find that the Sn particle expansion/shrinkage induced particle displacement is anisotropic: the displacement perpendicular to the electrode surface (z-axis) is more pronounced compared to the directions (x- and y-axis) along the electrode surface. This anisotropic particle displacement leads to an anisotropic volume variation at the electrode level and eventually generates a net electrode expansion towards the separator after cycling, which could be one of the root causes of mechanical detachment and delamination of electrodes during long-term operation. The unraveled chemical evolution of Li-Sn and deep insights into the microstructural evolution of Sn anode provided here could guide future design and engineering of Sn and other alloy anodes for high energy density Li- and Na-ion batteries.

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Sandwich structured ultra-strong-heat-shielding aerogel/copper composite insulation board for safe lithium-ion batteries modules Heng Yu, Xiaowei Mu, Yulu Zhu, Can Liao, Longfei Han, Jingwen Wang, Wei Cai, Yongchun Kan, Lei Song, Yuan Hu 2023, 76(1): 438-447.  DOI: 10.1016/j.jechem.2022.10.009 Abstract ( 14 )   PDF (2871KB) ( 2 )   The fire hazard of lithium-ion batteries (LIBs) modules is extremely serious due to their high capacity. Moreover, once a battery catches fire, it can easily result in a fire of the entire LIBs modules. In this work, a sandwich structure composite thermal insulation (STI) board (copper//silica dioxide aerogel//copper) with the advantages of low thermal conductivity (0.031 W m-1 K-1), low surface radiation emissivity (0.1) and good thermal convection inhibition effect has been designed. The thermal runaway (TR) occurrence time of adjacent LIBs increases from 1384 s to more than 6 h + due to the protection of STI board. No TR propagation occurs within LIBs modules with protect of a STI board when a battery catches fire. The ultra-strong-heat-shielding mechanism of STI board has been revealed. The TR propagation of LIBs modules has been insulated effectively by STI board through reducing the heat transfer of convection, conduction and radiation. The air flow rate between the heater and LIBs and radiant heat absorbed by LIBs decrease by 63.5% and 35.1% with protection of STI board, respectively. A high temperature difference inside the STI board is also formed. This work provides direction for the designing of safe thermal insulation board for LIBs modules.

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Synthesis of phosphonated graphene oxide by electrochemical exfoliation to enhance the performance and durability of high-temperature proton exchange membrane fuel cells Jianuo Chen, Zunmin Guo, Maria Perez-Page, Yifeng Jia, Ziyu Zhao, Stuart M. Holmes 2023, 76(1): 448-458.  DOI: 10.1016/j.jechem.2022.09.028 Abstract ( 8 )   PDF (3534KB) ( 7 )   The doping of functionalized graphene oxide (GO) in the membranes becomes a promising method for improving the performance of high-temperature proton exchange membrane fuel cells (HT-PEMFC). Phosphonated graphene oxide (PGO) with a P/O ratio of 8.5% was quickly synthesised by one-step electrochemical exfoliation based on a three-dimensiaonal (3D) printed reactor and natural graphite flakes. Compared with the GO prepared by the two-step electrochemical exfoliation method, the PGO synthesized by the one-step electrochemical exfoliation can better improve the performance of the membrane-electrode-assembly (MEA) based on the polybenzimidazole (PBI) membrane in the HT-PEMFC. The doping of 1.5 wt% GO synthesised by electrochemical exfoliation with the 2-step method or reactor method in PBI increased the peak power density by 17.4% or 35.4% compared to MEA based on pure PBI membrane at 150 °C, respectively. In addition, the doping of PGO in PBI improves its durability under accelerated stress test (AST).

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The key challenges and future opportunities of electrochemical capacitors Fangyan Liu, Xinliang Feng, Zhong-Shuai Wu 2023, 76(1): 459-461.  DOI: 10.1016/j.jechem.2022.09.019 Abstract ( 6 )   PDF (358KB) ( 4 )

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A hierarchically structured tin-cobalt composite with an enhanced electronic effect for high-performance CO2 electroreduction in a wide potential range Xingxing Jiang, Xuan Li, Yan Kong, Chen Deng, Xiaojie Li, Qi Hu, Hengpan Yang, Chuanxin He 2023, 76(1): 462-469.  DOI: 10.1016/j.jechem.2022.10.008 Abstract ( 5 )   PDF (1904KB) ( 2 )   Earth-abundant and nontoxic Sn-based materials have been regarded as promising catalysts for the electrochemical conversion of CO2 to C1 products, e.g., CO and formate. However, it is still difficult for Sn-based materials to obtain satisfactory performance at low-to-moderate overpotentials. Herein, a simple and facile electrospinning technique is utilized to prepare a composite of a bimetallic Sn-Co oxide/carbon matrix with a hollow nanotube structure (SnCo-HNT). SnCo-HNT can maintain > 90 % faradaic efficiencies for C1 products within a wide potential range from - 0.6 VRHE to - 1.2 VRHE, and a highest 94.1 % selectivity towards CO in an H-type cell. Moreover, a 91.2 % faradaic efficiency with a 241.3 mA cm-2 partial current density for C1 products could be achieved using a flow cell. According to theoretical calculations, the fusing of Sn/Co oxides on the carbon matrix accelerates electron transfer at the atomic level, causing electron deficiency of Sn centers and reversible variation between Co2+ and Co3+ centers. The synergistic effect of the Sn/Co composition improves the electron affinity of the catalyst surface, which is conducive to the adsorption and stabilization of key intermediates and eventually increases the catalytic activity in CO2 electroreduction. This study could provide a new strategy for the construction of oxide-derived catalysts for CO2 electroreduction.

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Schiff-base polymer derived FeCo-N-doped porous carbon flowers as bifunctional oxygen electrocatalyst for long-life rechargeable zinc-air batteries Yusong Deng, Jiahui Zheng, Bei Liu, Huaming Li, Mei Yang, Zhiyu Wang 2023, 76(1): 470-478.  DOI: 10.1016/j.jechem.2022.09.031 Abstract ( 4 )   PDF (2128KB) ( 2 )   Rational design and exploration of low-cost and robust bifunctional oxygen electrocatalysts are vitally important for developing high-performance zinc-air batteries (ZABs). Herein, we reported a facile yet cost-efficient approach to construct a bifunctional oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) electrocatalyst composed of N-doped porous carbon nanosheet flowers decorated with FeCo nanoparticles (FeCo/N-CF). Rational design of this catalyst is achieved by designing Schiff-base polymer with unique molecular structure via hydrogen bonding of cyanuramide and terephthalaldehyde polycondensate in the presence of metal cations. It exhibits excellent activity and stability for electrocatalysis of ORR/OER, enabling ZAB with a high peak power density of 172 mW cm-2 and a large specific capacity of 811 mA h g-1Zn at large current. The rechargeable ZAB demonstrates excellent durability for 1000 h with slight voltage decay, far outperforming a couple of precious Pt/Ir-based catalysts. Density functional theory (DFT) calculations reveal that high activity of bimetallic FeCo stems from enhanced O2 and OH- adsorption and accelerated O2 dissociation by OO bond activation.

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A comprehensive review of pre-lithiation/sodiation additives for Li-ion and Na-ion batteries Pranav Kulkarni, Hyunyoung Jung, Debasis Ghosh, Mohammed Jalalah, Mabkhoot Alsaiari, Farid A. Harraz, R. Geetha Balakrishna 2023, 76(1): 479-494.  DOI: 10.1016/j.jechem.2022.10.001 Abstract ( 115 )   PDF (2176KB) ( 95 )   Lithium/Sodium-ion batteries (LIB/SIB) have attracted enormous attention as a promising electrochemical energy storage system due to their high energy density and long cycle life. One of the major hurdles is the initial irreversible capacity loss during the first few cycles owing to forming the solid electrolyte interphase layer (SEI). This process consumes a profusion of lithium/sodium, which reduces the overall energy density and cycle life. Thus, a suitable approach to compensate for the irreversible capacity loss must be developed to improve the energy density and cycle life. Pre-lithiation/sodiation is a widely accepted process to compensate for the irreversible capacity loss during the initial cycles. Various strategies such as physical, chemical, and electrochemical pre-lithiation/sodiation have been explored; however, these approaches add an extra step to the current manufacturing process. Alternative to these strategies, pre-lithiation/sodiation additives have attracted enormous attention due to their easy adaptability and compatibility with the current battery manufacturing process. In this review, we consolidate recent developments and emphasize the importance of using pre-lithiation/sodiation additives (anode and cathode) to overcome the irreversible capacity loss during the initial cycles in lithium/sodium-ion batteries. This review also addresses the technical and scientific challenges of using pre-lithiation/sodiation additives and offers the insights to boost the energy density and cycle life with their possible commercial exploration. The most important prerequisites for designing effective pre-lithiation/sodiation additives have been explored and the future directions have been discussed.

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Enhancement and recovery of photoluminescence and stability by multifunctional etching ligands treatment for perovskite nanocrystals Yang Zhao, Haipeng Zeng, Xueqing Cai, Yingshan Zhou, Yangming Jiang, Xin Zheng, Lin Li, Shujing Zhang, Long Luo, Weixi Li, Xiaoru Zhang, Ranran Liu, Wenxi Liang, Rui Guo, Xiong Li 2023, 76(1): 495-502.  DOI: 10.1016/j.jechem.2022.09.043 Abstract ( 8 )   PDF (1448KB) ( 3 )   Perovskite nanocrystals (PNCs) have recently become promising optoelectronic materials due to their excellent photophysical properties. However, the highly dynamic binding state between ligands and the surface of PNCs has severely restricted their luminescent properties and stabilities. In this work, 1,3-bisbenzyl-2-oxoimidazolidine-4,5-dicarboxylic acid (cycle acid, CA) is introduced as both an etchant and a ligand upon post-synthetic surface treatment of PNCs. By removing the imperfect octahedrons [PbX6]4- and passivating the surface defects synergistically, this treatment improves photoluminescence quantum yields from 76% to 95% and enhances the stability of PNCs against polar solvent, moisture, heat, and illumination. Meanwhile, CA can effectively and instantly recover the luminescence emission for aged PNCs. As a result, the CA-CsPbBr3 PNCs and CA-CsPbIxBr3-x PNCs are applied as color-converting layers on a blue LED chip for warm white light-emitting diodes (WLEDs) with a color coordinate of (0.41, 0.40). Importantly, the CA-based WLED device exhibits superior stability in operational conditions.

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3D spiny AlF3/Mullite heterostructure nanofiber as solid-state polymer electrolyte fillers with enhanced ionic conductivity and improved interfacial compatibility Weicui Liu, Lingshuai Meng, Xueqiang Liu, Lu Gao, Xiaoxiao Wang, Junbao Kang, Jingge Ju, Nanping Deng, Bowen Cheng, Weimin Kang 2023, 76(1): 503-515.  DOI: 10.1016/j.jechem.2022.09.042 Abstract ( 6 )   PDF (2439KB) ( 6 )   Lithium metal batteries assembled with solid-state electrolyte can offer high safety and volumetric energy density compared to liquid electrolyte. The polymer solid-state electrolytes of poly(ethylene oxide) (PEO) are widely used in lithium metal solid-state batteries due to their unique properties. However, there are still some defects such as low ionic conductivity at room temperature and weak inhibition of lithium dendrite growth. Herein, the spiny inorganic nanofibers heterostructure with mullite whiskers grown on the surface of aluminum fluoride (AlF3) nanofibers are introduced into the PEO-LiTFSI electrolytes for the first time to prepare composite solid-state electrolytes. The AlF3 as a strong Lewis acid can adsorb anions and promote the dissociation of Li salts. Besides, the specially three-dimensional (3D) structure enlarges the effective contacting interface with the PEO polymer, which allows the lithium ions to be transported not only along the large aspect ratio of AlF3 nanofibers, but also along the mullite phase in the transmembrane direction rapidly. Thereby, the transport channel of lithium ions at the spiny inorganic nanofibers-polymer interface is further improved. Benefiting from these advantages, the obtained composite solid-state electrolyte has a high ionic conductivity of 1.58 × 10-4 S cm-1 at 30 °C and the lithium ions transfer number of 0.53. In addition, the AlF3 has strong binding energy with anions, low electronic conductivity and wide electrochemical stability window, and reduced nucleation overpotential of lithium during cycling, which is positive for lithium dendrite suppression in solid-state electrolytes. Thus, the assembled symmetric Li/Li symmetric batteries exhibit stable cycling performance at different area capacities of 0.15, 0.2, 0.3 and 0.4 mA h cm-2. More importantly, the LiFePO4 (LFP)/Li battery still has 113.5 mA h g-1 remaining after 400 cycles at 50 °C and the Coulomb efficiency is nearly 100% during the long cycle. Overall, the interconnected structure of 3D spiny inorganic heterostructure nanofiber constitutes fast and uninterrupted lithium ions transport channels, maximizing the synergistic effect of interfacial transport of inorganic fillers and reducing PEO crystallinity, thus providing a novel approach to high performance solid-state electrolytes.

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External-to-internal synergistic strategy to enable multi-scale stabilization of LiCoO2 at high-voltage Shuaipeng Hao, Yunjiao Li, Jiachao Yang, Shan Wang, Zhouliang Tan, Xiaoming Xi, Zhenjiang He, Panpan Zhang 2023, 76(1): 516-527.  DOI: 10.1016/j.jechem.2022.09.033 Abstract ( 7 )   PDF (4117KB) ( 5 )   High-voltage LiCoO2 (LCO) offers a prelude to breaking the bottleneck of the energy density of lithium-ion batteries, however, LiCoO2 is subject to serious structural and interfacial degradation above voltages >4.55 V (vs. Li/Li+). Herein, an in-situ Li6.25La3Zr2Al0.25O12 (LLZAO) layer is constructed on the LCO surface to achieve operating voltage at 4.6 V. The detailed characterizations (ex-situ XRD, ex-situ Raman, DFT, etc.) reveal that the LLZAO layer greatly enhances Li+ conductivity attributed to the ion-conducting layer on the surface/interface, and closely combines with LiCoO2 particle to ensure stable cathode/electrolyte interface, thus suppressing the highly reactive Co4+ and O- triggered surface side reactions at high-voltage. Moreover, the introduction of La3+/Zr4+/Al3+ with a larger ionic radius (La3+/Zr4+ are larger than Co3+) and weaker electronegativity (La/Zr/Al are weaker than Co) into Co3+ sites readjusts the electron cloud density between Co-O-Li, which reinforces the Co-O bond and widens the band-center gap of Co 3d and O 2p, thus restraining the detrimental phase transition (from H3 to H1-3 phase) and the formation of Co3O4 spinel phase (attributed to lattice oxygen release), subsequently alleviating the particle cracking and structural collapse during repeated Li+ de/intercalation. Therefore, after 100 cycles at 3.0-4.6 V, LCO@1.0LLZAO exhibits a superior discharge capacity of 188.5 mA h g-1, with a capacity retention of 85.1%. The above research has brought about meaningful guidance for the evolution of cathode materials with high voltage.

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Design strategies of performance-enhanced Se cathodes for Li-Se batteries and beyond Weiling Qiu, Xiang Long Huang, Ye Wang, Chi Feng, Haining Ji, Hua Kun Liu, Shi Xue Dou, Zhiming Wang 2023, 76(1): 528-546.  DOI: 10.1016/j.jechem.2022.09.026 Abstract ( 9 )   PDF (3567KB) ( 1 )   Lithium-selenium (Li-Se) batteries are deemed as an emerging high energy density electrochemical energy storage system owing to their high specific capacity and volume capacity. Prior to their practicality, a series of critical challenges from the Se cathode side need to be overcome including low reactivity of bulk Se, shuttle effect of intermediates, sluggish redox kinetics of polyselenides, and volume change etc. In this review, recent progress on design strategies of functional Se cathodes are comprehensively summarized and discussed. Following the significance and key challenges, various efficient functionalized strategies for Se cathodes are presented, encompassing covalent bonding, nanostructure construction, heteroatom doping, component hybridization, and solid solution formation. Specially, the universality of these functional strategies are successfully extended into Na-Se batteries, K-Se batteries, and Mg-Se batteries. At last, a brief summary is made and some perspectives are offered with the goal of guiding future research advances and further exploration of these strategies.

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Achieving high-capacity and long-life K+ storage enabled by constructing yolk-shell Sb2S3@N, S-doped carbon nanorod anodes Bensheng Xiao, Hehe Zhang, Zhefei Sun, Miao Li, Yingzhu Fan, Haichen Lin, Haodong Liu, Bing Jiang, Yanbin Shen, Ming-Sheng Wang, Meicheng Li, Qiaobao Zhang 2023, 76(1): 547-556.  DOI: 10.1016/j.jechem.2022.09.050 Abstract ( 11 )   PDF (3089KB) ( 4 )   As promising anode candidates for potassium-ion batteries (PIBs), antimony sulfide (Sb2S3) possesses high specific capacity but suffers from massive volume expansion and sluggish kinetics due to the large K+ insertion, resulting in inferior cycling and rate performance. To address these challenges, a yolk-shell structured Sb2S3 confined in N, S co-doped hollow carbon nanorod (YS-Sb2S3@NSC) working as a viable anode for PIBs is proposed. As directly verified by in situ transmission electron microscopy (TEM), the buffer space between the Sb2S3 core and thin carbon shell can effectively accommodate the large expansion stress of Sb2S3 without cracking the shell and the carbon shell can accelerate electron transport and K+ diffusion, which plays a significant role in reinforcing the structural stability and facilitating charge transfer. As a result, the YS-Sb2S3@NSC electrode delivers a high reversible K+ storage capacity of 594.58 mA h g-1 at 0.1 A g-1 and a long cycle life with a slight capacity degradation (0.01% per cycle) for 2000 cycles at 1 A g-1 while maintaining outstanding rate capability. Importantly, utilizing in in situ/ex situ microscopic and spectroscopic characterizations, the origins of performance enhancement and K+ storage mechanism of Sb2S3 were clearly elucidated. This work provides valuable insights into the rational design of high-performance and durable transition metal sulfides-based anodes for PIBs.

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Enabling stable 4.6 V LiCoO2 cathode through oxygen charge regulation strategy Wen Zhang, Xiaoyu Zhang, Fangyuan Cheng, Meng Wang, Jing Wan, Yuyu Li, Jia Xu, Yi Liu, Shixiong Sun, Yue Xu, Chun Fang, Qing Li, Jiantao Han, Yunhui Huang 2023, 76(1): 557-565.  DOI: 10.1016/j.jechem.2022.09.034 Abstract ( 12 )   PDF (2144KB) ( 6 )   LiCoO2 is the preferred cathode material for consumer electronic products due to its high volumetric energy density. However, the unfavorable phase transition and surface oxygen release limits the practical application of LiCoO2 at a high-voltage of 4.6 V to achieve a higher energy density demanded by the market. Herein, both bulk and surface structures of LiCoO2 are stabilized at 4.6 V through oxygen charge regulation by Gd-gradient doping. The enrichment of highly electropositive Gd on LiCoO2 surface will increase the effective charge on oxygen and improve the oxygen framework stability against oxygen loss. On the other hand, Gd ions occupy the Co-sites and suppress the unfavorable phase transition and micro-crack. The modified LiCoO2 exhibits superior cycling stability with capacity retention of 90.1% over 200 cycles at 4.6 V, and also obtains a high capacity of 145.7 mAh/g at 5 C. This work shows great promise for developing high-voltage LiCoO2 at 4.6 V and the strategy could also contribute to optimizing other cathode materials with high voltage and large capacity, such as cobalt-free high-nickel and lithium-rich manganese-based cathode materials.

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Hierarchically wood-derived integrated electrode with tunable superhydrophilic/superaerophobic surface for efficient urea electrolysis Yu Liao, Songlin Deng, Yan Qing, Han Xu, Cuihua Tian, Yiqiang Wu 2023, 76(1): 566-575.  DOI: 10.1016/j.jechem.2022.10.007 Abstract ( 17 )   PDF (2945KB) ( 4 )   Conferring surfaces with superhydrophilic/superaerophobic characteristics is desirable for synthesizing efficient gas reaction catalysts. However, complicated procedures, high costs, and poor interfaces hinder commercialization. Here, an integrated electrode with tunable wettability derived from a hierarchically porous wood scaffold was well designed for urea oxidation reaction (UOR). Interestingly, the outer surface of the wood lumen was optimized to the preferred wettability via stoichiometry to promote electrolyte permeation and gas escape. This catalyst exhibits outstanding activity and durability for UOR in alkaline media, requiring only a potential of 1.36 V (vs. RHE) to deliver 10 mA cm-2 and maintain its activity without significant decay for 60 h. These experiments and theoretical calculations demonstrate that the nickel (oxy)hydroxide layer formed through surface reconstruction of nickel nanoparticles improves the active sites and intrinsic activity. Moreover, the superwetting properties of the electrode promote mass transfer by guaranteeing substantial contact with the electrolyte and accelerating the separation of gaseous products during electrocatalysis. These findings provide the understanding needed to manipulate the surface wettability through rational design and fabrication of efficient electrocatalysts for gas-evolving processes.

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Interfacial design of silicon/carbon anodes for rechargeable batteries: A review Quanyan Man, Yongling An, Chengkai Liu, Hengtao Shen, Shenglin Xiong, Jinkui Feng 2023, 76(1): 576-600.  DOI: 10.1016/j.jechem.2022.09.020 Abstract ( 20 )   PDF (6925KB) ( 18 )   Silicon (Si) has been studied as a promising alloying type anode for lithium-ion batteries due to its high specific capacity, low operating potential and abundant resources. Nevertheless, huge volume expansion during alloying/dealloying processes and low electronic conductivity of Si anodes restrict their electrochemical performance. Thus, carbon (C) materials with special physical and chemical properties are applied in Si anodes to effectively solve these problems. This review focuses on current status in the exploration of Si/C anodes, including the lithiation mechanism and solid electrolyte interface formation, various carbon sources in Si/C anodes, such as traditional carbon sources (graphite, pitch, biomass), and novel carbon sources (MXene, graphene, MOFs-derived carbon, graphdiyne, etc.), as well as interfacial bonding modes of Si and C in the Si/C anodes. Finally, we summarize and prospect the selection of carbonaceous materials, structural design and interface control of Si/C anodes, and application of Si/C anodes in all-solid-state lithium-ion batteries and sodium-ion batteries et al. This review will help researchers in the design of novel Si/C anodes for rechargeable batteries.

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Recent advances in regulating the performance of acid oxygen reduction reaction on carbon-supported non-precious metal single atom catalysts Yanqiu Wang, Jiayu Hao, Yang Liu, Min Liu, Kuang Sheng, Yue Wang, Jun Yang, Jie Li, Wenzhang Li 2023, 76(1): 601-616.  DOI: 10.1016/j.jechem.2022.09.047 Abstract ( 14 )   PDF (4975KB) ( 14 )   Developing high performance and low-cost catalysts for oxygen reduction reaction (ORR) in challenging acid condition is vital for proton-exchange-membrane fuel cells (PEMFCs). Carbon-supported non-precious metal single atom catalysts (SACs) have been identified as potential catalysts in the field. Great advance has been obtained in constructing diverse active sites of SACs for improving the performance and understanding the fundamental principles of regulating acid ORR performance. However, the ORR performance of SACs is still unsatisfactory. Importantly, microenvironment adjustment of SACs offers chance to promote the performance of acid ORR. In this review, acid ORR mechanism, attenuation mechanism and performance improvement strategies of SACs are presented. The strategies for promoting ORR activity of SACs include the adjustment of center metal and its microenvironment. The relationship of ORR performance and structure is discussed with the help of advanced experimental investigations and theoretical calculations, which will offer helpful direction for designing advanced SACs for ORR.

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A cobalt(II) porphyrin with a tethered imidazole for efficient oxygen reduction and evolution electrocatalysis Xialiang Li, Ping Li, Jindou Yang, Lisi Xie, Ni Wang, Haitao Lei, Chaochao Zhang, Wei Zhang, Yong-Min Lee, Weiqiang Zhang, Shunichi Fukuzumi, Wonwoo Nam, Rui Cao 2023, 76(1): 617-621.  DOI: 10.1016/j.jechem.2022.10.010 Abstract ( 23 )   PDF (800KB) ( 12 )

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Multiatom activation of single-atom electrocatalysts via remote coordination for ultrahigh-rate two-electron oxygen reduction Xiaoqing Liu, Rui Chen, Wei Peng, Lichang Yin, De'an Yang, Feng Hou, Liqun Wang, Ji Liang 2023, 76(1): 622-630.  DOI: 10.1016/j.jechem.2022.10.015 Abstract ( 12 )   PDF (2500KB) ( 6 )   Electrocatalytic oxygen reduction via a two-electron pathway (2e--ORR) is a promising and eco-friendly route for producing hydrogen peroxide (H2O2). Single-atom catalysts (SACs) typically show excellent selectivity towards 2e--ORR due to their unique electronic structures and geometrical configurations. The very low density of single-atom active centers, however, often leads to unsatisfactory H2O2 yield rate, significantly inhibiting their practical feasibility. Addressing this, we herein introduce fluorine as a secondary doping element into conventional SACs, which does not directly coordinate with the single-atom metal centers but synergize with them in a remote manner. This strategy effectively activates the surrounding carbon atoms and converts them into highly active sites for 2e--ORR. Consequently, a record-high H2O2 yield rate up to 27 mol g-1 h-1 has been achieved on the Mo-F-C catalyst, with high Faradaic efficiency of 90%. Density functional theory calculations further confirm the very kinetically facile 2e--ORR over these additional active sites and the superiority of Mo as the single-atom center to others. This strategy thus not only provides a high-performance electrocatalyst for 2e--ORR but also should shed light on new strategies to significantly increase the active centers number of SACs.

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A homogeneous and mechanically stable artificial diffusion layer using rigid-flexible hybrid polymer for high-performance lithium metal batteries Zhenkang Lin, Yuyan Ma, Wei Wang, Yu He, Menghao Wang, Jun Tang, Cheng Fan, Kening Sun 2023, 76(1): 631-638.  DOI: 10.1016/j.jechem.2022.09.030 Abstract ( 7 )   PDF (1134KB) ( 8 )   Artificial solid electrolyte interphase (SEI) is promising to inhibit uncontrollable lithium dendrites and enable long cycling stability for lithium metal batteries. However, the essential mechanical stability is limited since organic layers generally have low modulus whereas intrinsic brittleness for inorganic ones remains a great concern. Polymer-based SEIs with rigid and flexible chains in adequate mechanical properties are supposed to address this issue. Herein, a homogeneous and mechanically stable diffusion layer is achieved by blending rigid chains of polyphenylene sulfone (PPSU) with flexible chains of poly (vinylidene fluoride) (PVDF) in a hybrid membrane, enabling uniform diffusion and stabilizing the lithium metal anode. The Li||Cu cell with the protected electrode exhibits a long lifetime more than 450 cycles (0.5 mA cm-2, 1.0 mA h cm-2) (fourfold longer than the control group) with higher average Coulombic efficiency of 98.7%. Enhanced performances are also observed at Li||Li and full cell configurations. The improved performances are attributed to the controlled morphology and stable interphase, according to scanning electron microscopy (SEM) and electrochemical impedance. This research advances the idea of uniform lithium plating and provides a new insight on how to create a homogeneous and mechanically stable diffusion layer using rigid-flexible polymers.

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Ultrathin organic polymer with p-π conjugated structure for simultaneous photocatalytic disulfide bond generation and CO2 reduction Linquan Hou, Zhunyun Tang, Guojiang Mao, Shiheng Yin, Bei Long, Tao Ouyang, Guo-Jun Deng, Atif Ali, Ting Song 2023, 76(1): 639-647.  DOI: 10.1016/j.jechem.2022.10.003 Abstract ( 10 )   PDF (2140KB) ( 9 )   Combining photocatalytic organic reactions with CO2 reduction is an efficient solar energy utilization mode, but it is still limited by the organic species that can be matched and the low conversion. Herein, ultrathin organic polymer with p-π conjugated structure (TPP) was rationally designed and prepared, and showed a high yield of CO (15.2 mmol g-1) and conversion of SS coupled products (100%), far exceeding the organic polymer with PO structure. The enhanced photoredox activity of TPP is ascribed to the orbital interaction between the p-orbital on phosphorus and the π-orbitals of aromatic, which can accelerate the photoinduced charge carrier separation and improve the CO2 adsorption capacity. TPP can also be used for the dehydrocoupling of various benzyl mercaptans to the corresponding SS bond products. This work provides a new concept for the efficient synthesis of disulfide bonds combined with CO2 reduction in a photoreaction system.

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In situ generation of Li3N concentration gradient in 3D carbon-based lithium anodes towards highly-stable lithium metal batteries Wenzhu Cao, Weimin Chen, Mi Lu, Cheng Zhang, Du Tian, Liang Wang, Faquan Yu 2023, 76(1): 648-656.  DOI: 10.1016/j.jechem.2022.09.025 Abstract ( 14 )   PDF (2704KB) ( 13 )   The uncontrolled dendrite growth of lithium metal anodes (LMAs) caused by unstable anode/electrolyte interface and uneven lithium deposition have impeded the practical applications of lithium metal batteries (LMBs). Constructing a robust artificial solid electrolyte interphase (SEI) and regulating the lithium deposition behavior is an effective strategy to address these issues. Herein, a three-dimensional (3D) lithium anode with gradient Li3N has been in-situ fabricated on carbon-based framework by thermal diffusion method (denoted as CC/Li/Li3N). Density functional theory (DFT) calculations reveal that Li3N can effectively promote the transport of Li+ due to the low energy barrier of Li+ diffusion. As expected, the Li3N-rich conformal artificial SEI film can not only effectively stabilize the interface and avoid parasitic reactions, but also facilitate fast Li+ transport across the SEI layer. The anode matrix with uniformly distributed Li3N can enable homogenous deposition of Li, thus preventing Li dendrite propagation. Benefiting from these merits, the CC/Li/Li3N anode achieves ultralong-term cycling for >1000 h at a current density of 2 mA cm-2 and dendrite-free Li deposition at an ultrahigh rate of 20 mA cm-2. Moreover, the full cells coupled with LiFePO4 cathodes show extraordinary cycling stability for >300 cycles in liquid-electrolyte-based batteries and display a high-capacity retention of 96.7% after 100 cycles in solid-state cells, demonstrating the promising prospects for the practical applications of LMBs.