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2023, Vol. 81, No. 6　Online: 15 June 2023

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Reviewing perovskite oxide sites influence on electrocatalytic reactions for high energy density devices Lorrane C. C. B. Oliveira, Raissa Venâncio, Paulo V. F. de Azevedo, Chayene G. Anchieta, Thayane C. M. Nepel, Cristiane B. Rodella, Hudson Zanin, Gustavo Doubek 2023, 81(6): 1-19.  DOI: 10.1016/j.jechem.2023.02.013 Abstract ( 17 )   PDF (12325KB) ( 12 )   Batteries, fuel cells, and supercapacitors are electrochemical devices already on the market and still need a boost in kinetics to match the high energy density demand of applications. Perovskites have attracted the scientific community's attention in the last decade due to their electrocatalytic activity, chemical and structural properties, tunability, low cost, and scalability. Efforts have been made to understand the active sites and the operational mechanisms in perovskite oxides to shape them as an electrocatalyst in advanced energy devices. Understanding the role of perovskites is the key to engineering more controlled and efficient electrocatalysts via chemical synthesis, and there is still much to do. This review highlights the use of perovskites in different energy storage and conversion systems. The A, B, and A&B doping-site effects are analyzed to understand the opportunities and challenges related to this class of materials. In addition, the synthesis methods and the properties related to the doping site are described and summarized.

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A thin Si nanowire network anode for high volumetric capacity and long-life lithium-ion batteries Ibrahim Saana Amiinu, Sumair Imtiaz, Hugh Geaney, Tadhg Kennedy, Nilotpal Kapuria, Shalini Singh, Kevin M Ryan 2023, 81(6): 20-27.  DOI: 10.1016/j.jechem.2023.02.025 Abstract ( 16 )   PDF (10825KB) ( 7 )   Silicon nanowires (Si NWs) have been widely researched as the best alternative to graphite anodes for the next-generation of high-performance lithium-ion batteries (LIBs) owing to their high capacity and low discharge potential. However, growing binder-free Si NW anodes with adequate mass loading and stable capacity is severely limited by the low surface area of planar current collectors (CCs), and is particularly challenging to achieve on standard pure-Cu substrates due to the ubiquitous formation of Li+ inactive silicide phases. Here, the growth of densely-interwoven In-seeded Si NWs is facilitated by a thin-film of copper-silicide (CS) network in situ grown on a Cu-foil, allowing for a thin active NW layer (<10 µm thick) and high areal loading (≈1.04 mg/cm2) binder-free electrode architecture. The electrode exhibits an average Coulombic efficiency (CE) of >99.6% and stable performance for >900 cycles with ≈88.7% capacity retention. More significantly, it delivers a volumetric capacity of ≈1086.1 mA h/cm3 at 5C. The full-cell versus lithium manganese oxide (LMO) cathode delivers a capacity of ≈1177.1 mA h/g at 1C with a stable rate capability. This electrode architecture represents significant advances toward the development of binder-free Si NW electrodes for LIB application.

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Multi-objective optimization of the cathode catalyst layer micro-composition of polymer electrolyte membrane fuel cells using a multi-scale, two-phase fuel cell model and data-driven surrogates Neil Vaz, Jaeyoo Choi, Yohan Cha, Jihoon kong, Yooseong Park, Hyunchul Ju 2023, 81(6): 28-41.  DOI: 10.1016/j.jechem.2023.02.027 Abstract ( 20 )   PDF (5673KB) ( 8 )   Polymer electrolyte membrane fuel cells (PEMFCs) are considered a promising alternative to internal combustion engines in the automotive sector. Their commercialization is mainly hindered due to the cost and effectiveness of using platinum (Pt) in them. The cathode catalyst layer (CL) is considered a core component in PEMFCs, and its composition often considerably affects the cell performance (Vcell) also PEMFC fabrication and production Cstack costs. In this study, a data-driven multi-objective optimization analysis is conducted to effectively evaluate the effects of various cathode CL compositions on Vcell and Cstack. Four essential cathode CL parameters, i.e., platinum loading (LPt), weight ratio of ionomer to carbon (wtI/C), weight ratio of Pt to carbon (wtPt/c), and porosity of cathode CL (εcCL), are considered as the design variables. The simulation results of a three-dimensional, multi-scale, two-phase comprehensive PEMFC model are used to train and test two famous surrogates: multi-layer perceptron (MLP) and response surface analysis (RSA). Their accuracies are verified using root mean square error and adjusted R2. MLP which outperforms RSA in terms of prediction capability is then linked to a multi-objective non-dominated sorting genetic algorithm II. Compared to a typical PEMFC stack, the results of the optimal study show that the single-cell voltage, Vcell is improved by 28 mV for the same stack price and the stack cost evaluated through the U.S department of energy cost model is reduced by $5.86/kW for the same stack performance.

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State-of-the-art and future directions of machine learning for biomass characterization and for sustainable biorefinery Aditya Velidandi, Pradeep Kumar Gandam, Madhavi Latha Chinta, Srilekha Konakanchi, Anji reddy Bhavanam, Rama Raju Baadhe, Minaxi Sharma, James Gaffey, Quang D. Nguyen, Vijai Kumar Gupta 2023, 81(6): 42-63.  DOI: 10.1016/j.jechem.2023.02.020 Abstract ( 97 )   PDF (5443KB) ( 54 )   Machine learning (ML) has emerged as a significant tool in the field of biorefinery, offering the capability to analyze and predict complex processes with efficiency. This article reviews the current state of biorefinery and its classification, highlighting various commercially successful biorefineries. Further, we delve into different categories of ML models, including their algorithms and applications in various stages of biorefinery lifecycle, such as biomass characterization, pretreatment, lignin valorization, chemical, thermochemical and biochemical conversion processes, supply chain analysis, and life cycle assessment. The benefits and limitations of each of these algorithms are discussed in detail. Finally, the article concludes with a discussion of the limitations and future prospects of ML in the field of biorefineries.

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Organized macro-scale membrane size reduction in vanadium redox flow batteries: Part 1. General concept Abdulmonem Fetyan, Bronston P. Benetho, Musbaudeen O. Bamgbopa 2023, 81(6): 64-70.  DOI: 10.1016/j.jechem.2023.01.058 Abstract ( 9 )   PDF (1859KB) ( 4 )   The high costs of the currently used membranes in vanadium redox flow batteries (VRFBs) contribute to the price of the vanadium redox flow battery systems and therefore limit the market share of the VRFBs. Here we report a detailed simulation and experimental studies on the effect of membrane reduction of single-cell VRFB. Different simulated designs demonstrate that a proposed centred and double-strip membrane coverage showed a promising performance. Experimental charge-discharge profile of different membrane size reduction, which showed good agreement with simulated data, suggests that the membrane size can comfortably be reduced by up to 20% without severe efficiency or discharge capacity loss. Long-term cycling of 80% centred membrane coverage showed improved capacity retention during the latter cycles with almost 1% difference in capacity and only 2% in energy efficiency when compared to the fully covered-membrane cell. The results hold great promise for the development of cheap RFB stacks and facilitate the way to develop new cell designs with non-overlapping electrodes geometry. Therefore, giving more flexibility to improve the overall performance of the system.

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Hetero-interfacial nickel nitride/vanadium oxynitride porous nanosheets as trifunctional electrodes for HER, OER and sodium ion batteries Tuzhi Xiong, Jingting Li, Jagadish Chandra Roy, Malcolm Koroma, Zhixiao Zhu, Hao Yang, Lei Zhang, Ting Ouyang, M.-Sadeeq Balogun, Mohammad Al-Mamun 2023, 81(6): 71-81.  DOI: 10.1016/j.jechem.2023.01.064 Abstract ( 11 )   PDF (2956KB) ( 8 )   The development of single electrode with multifunctional purposes for electrochemical devices remains a symbolic challenge in recent technology. This work explores interfacially-rich transition metal nitride hybrid that consist of nickel nitride and vanadium oxynitride (VO0.26N0.52) on robust carbon fiber (denoted CF/Ni3N/VON) as trifunctional electrode for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and sodium ion batteries (SIBs). The as-prepared CF/Ni3N/VON exhibits low HER overpotential of 48 mV@10 mA cm-2, OER overpotential of 287 mV@10 mA cm-2, and sodium-ion anode storage reversible capacity of 555 mA h g-1@0.2 C. Theoretical analyses reveal that the Ni3N effectively facilitates hydrogen desorption for HER, increases the electrical conductivity for OER, and promotes the Na-ion storage intercalation process, while the VON substantially elevates the water dissociation kinetics for HER, accelerates the adsorption of OH* intermediate for OER and enhances the Na-ion surface adsorption storage process. Owing to the excellent HER and OER performances of the CF/Ni3N/VON electrode, an overall water splitting device denoted as CF/Ni3N/VON//CF/Ni3N/VON was not only assembled showing an operating voltage of 1.63 V at current density of 10 mA cm-2 but was also successfully self-powered by the assembled CF/Ni3N/VON//CF/Na3V2(PO4)3 flexible sodium ion battery. This work will contribute to the development of efficient and cost-effective flexible integrated electrochemical energy devices.

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Zn-doped nickel iron (oxy)hydroxide nanocubes passivated by polyanions with high catalytic activity and corrosion resistance for seawater oxidation So Jung Kim, Heechae Choi, Jeong Ho Ryu, Kang Min Kim, Sungwook Mhin, Arpan Kumar Nayak, Junghwan Bang, Minyeong Je, Ghulam Ali, Kyung Yoon Chung, Kyeong-Han Na, Won-Youl Choi, Sunghwan Yeo, Jin Uk Jang, HyukSu Han 2023, 81(6): 82-92.  DOI: 10.1016/j.jechem.2023.02.033 Abstract ( 10 )   PDF (10949KB) ( 8 )   Electrochemical water splitting to produce hydrogen fuel is a promising renewable energy-conversion technique. Large-scale electrolysis of freshwater may deplete water resources and cause water scarcity worldwide. Thus, seawater electrolysis is a potential solution to the future energy and water crisis. In seawater electrolysis, it is critical to develop cost-effective electrocatalysts to split seawater without chloride corrosion. Herein, we present zinc-doped nickel iron (oxy)hydroxide nanocubes passivated by negatively charged polyanions (NFZ-PBA-S) that exhibits outstanding catalytic activity, stability, and selectivity for seawater oxidation. Zn dopants and polyanion-rich passivated surface layers in NFZ-PBA-S could effectively repel chlorine ions and enhance corrosion resistance, enabling its excellent catalytic activity and stability for seawater oxidation.

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Understanding the hydrogen evolution reaction activity of doped single-atom catalysts on two-dimensional GaPS4 by DFT and machine learning Tianyun Liu, Xin Zhao, Xuefei Liu, Wenjun Xiao, Zijiang Luo, Wentao Wang, Yuefei Zhang, Jin-Cheng Liu 2023, 81(6): 93-100.  DOI: 10.1016/j.jechem.2023.02.018 Abstract ( 19 )   PDF (8480KB) ( 6 )   As a zero-carbon fuel, hydrogen can be produced via electrochemical water splitting using clean electric energy by the hydrogen evolution reaction (HER) process. The ultimate goal of HER catalyst is to replace the expensive Pt metal benchmark with a cheap one with equivalent activities. In this work, we investigated the possibility of HER process on single-atom catalysts (SACs) doped on two-dimensional (2D) GaPS4 materials, which have a large intrinsic band gap that can be regulated by doping and tensile strain. Based on the machine learning regression analysis, we can expand the prediction of HER performance to more catalysts without expensive DFT calculation. The electron affinity and first ionization energy are the two most important descriptors related to the HER behavior. Furthermore, constrain molecular dynamics with solvation models and constant potentials were applied to understand the dynamics barrier of HER process of Pt SAC on GaPS4 materials. These findings not only provide important insights into the catalytic properties of single-atom catalysts on GaPS4 2D materials, but also provides theoretical guidance paradigm for exploration of new catalysts.

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A facile finger-paint physical modification for bilateral electrode/electrolyte interface towards a stable aqueous Zn battery Hang Yang, Duo Chen, Yicheng Tan, Hao Xu, Li Li, Yiming Zhang, Chenglin Miao, Guangshe Li, Wei Han 2023, 81(6): 101-109.  DOI: 10.1016/j.jechem.2023.02.039 Abstract ( 6 )   PDF (8068KB) ( 3 )   Since the electrode/electrolyte interface (EEI) is the main redox center of electrochemical processes, proper manipulation of the EEI microenvironment is crucial to stabilize interfacial behaviors. Here, a finger-paint method is proposed to enable quick physical modification of glass-fiber separator without complicated chemical technology to modulate EEI of bilateral electrodes for aqueous zinc-ion batteries (ZIBs). An elaborate biochar derived from Aspergillus Niger is exploited as the modification agent of EEI, in which the multi-functional groups assist to accelerate Zn2+ desolvation and create a hydrophobic environment to homogenize the deposition behavior of Zn anode. Importantly, the finger-paint interface on separator can effectively protect cathodes from abnormal capacity fluctuation and/or rapid attenuation induced by H2O molecular on the interface, which is demonstrated in modified MnO2, V2O5, and KMnHCF-based cells. The as-proposed finger-paint method opens a new idea of bilateral interface engineering to facilitate the access to the practical application of the stable zinc electrochemistry.

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Symmetry-breaking of LiMn6 hexatomic-ring in grain surface of Li2MnO3 Lihang Wang, Shu Zhao, Boya Wang, Haijun Yu 2023, 81(6): 110-117.  DOI: 10.1016/j.jechem.2023.02.034 Abstract ( 10 )   PDF (11258KB) ( 4 )   LiMn6 hexatomic-rings act as functional units in Li-rich layered oxides (LLOs), which determine the capacity, voltage, and structural stability of LLOs. However, the symmetry of the LiMn6 hexatomic-ring is always broken, especially in the grain surface of LLOs, which will greatly affect its electrochemical performance. Herein, the symmetry-breaking of LiMn6 hexatomic-ring in the grain surface of Li2MnO3 was studied, and their effect on charge compensation mechanism and structure evolution behavior was thoroughly investigated. The results show that the electrochemical activity of the symmetry-broken LiMn6 hexatomic-ring is higher than that of the unbroken LiMn6, and the former is more favorable for spinelization on the grain surface. Furthermore, the exposure proportion of crystallographic planes with different symmetry-broken LiMn6 hexatomic-ring has also been discussed, which can be adjusted by changing the partial pressure of oxygen. The in-depth understanding of the symmetry-breaking of LiMn6 hexatomic-ring will provide more targeted strategies for designing high-performance LLOs cathodes for lithium-ion batteries.

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Uncertainty quantification of predicting stable structures for high-entropy alloys using Bayesian neural networks Yonghui Zhou, Bo Yang 2023, 81(6): 118-124.  DOI: 10.1016/j.jechem.2023.02.028 Abstract ( 10 )   PDF (5386KB) ( 9 )   High entropy alloys (HEAs) have excellent application prospects in catalysis because of their rich components and configuration space. In this work, we develop a Bayesian neural network (BNN) based on energies calculated with density functional theory to search the configuration space of the CoNiRhRu HEA system. The BNN model was developed by considering six independent features of Co-Ni, Co-Rh, Co-Ru, Ni-Rh, Ni-Ru, and Rh-Ru in different shells and energies of structures as the labels. The root mean squared error of the energy predicted by BNN is 1.37 meV/atom. Moreover, the influence of feature periodicity on the energy of HEA in theoretical calculations is discussed. We found that when the neural network is optimized to a certain extent, only using the accuracy indicator of root mean square error to evaluate model performance is no longer accurate in some scenarios. More importantly, we reveal the importance of uncertainty quantification for neural networks to predict new structures of HEAs with proper confidence based on BNN.

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Amorphous Sn(HPO4)2-derived phosphorus-modified Sn/SnOx core/shell catalyst for efficient CO2 electroreduction to formate Chunfeng Cheng, Tianfu Liu, Yi Wang, Pengfei Wei, Jiaqi Sang, Jiaqi Shao, Yanpeng Song, Yipeng Zang, Dunfeng Gao, Guoxiong Wang 2023, 81(6): 125-131.  DOI: 10.1016/j.jechem.2022.12.022 Abstract ( 10 )   PDF (5073KB) ( 8 )   Simultaneously achieving high activity, selectivity and stability for electrochemical CO2 reduction reaction (CO2RR) remains great challenges. Herein, a phosphorus-modified Sn/SnOx core/shell (P-Sn/SnOx) catalyst, derived from in situ electrochemical reduction of an amorphous Sn(HPO4)2 pre-catalyst, exhibits high CO2RR performance. The total Faradaic efficiency (FE) of C1 products is close to 100% in a broad potential range from -0.49 to -1.02 V vs. reversible hydrogen electrode, and a total current density of 315.0 mA cm-2 is achieved. Moreover, the P-Sn/SnOx catalyst maintains a formate FE of ∼90% for 120 h. Density functional theory calculations suggest that the phosphorus-modified Sn/SnOx core/shell structure effectively facilitates formate production by enhancing CO2 adsorption and improving free energy profile of formate formation.

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Experimental and theoretical investigation of high-entropy-alloy/support as a catalyst for reduction reactions Wail Al Zoubi, Bassem Assfour, Abdul Wahab Allaf, Stefano Leoni, Jee-Hyun Kang, Young Gun Ko 2023, 81(6): 132-142.  DOI: 10.1016/j.jechem.2023.02.042 Abstract ( 10 )   PDF (29199KB) ( 2 )   Control of chemical composition and incorporation of multiple metallic elements into a single metal nanoparticle (NP) in an alloyed or a phase-segregated state hold potential scientific merit; however, developing libraries of such structures using effective strategies is challenging owing to the thermodynamic immiscibility of repelling constituent metallic elements. Herein, we present a one-pot interfacial plasma-discharge-driven (IP-D) synthesis strategy for fabricating stable high-entropy-alloy (HEA) NPs exhibiting ultrasmall size on a porous support surface. Accordingly, an electric field was applied for 120 s to enhance the incorporation of multiple metallic elements (i.e., CuAgFe, CuAgNi, and CuAgNiFe) into ally HEA-NPs. Further, NPs were attached to a porous magnesium oxide surface via rapid cooling. With solar light as the sole energy input, the CuAgNiFe catalyst was investigated as a reusable and sustainable material exhibiting excellent catalytic performance (100% conversion and 99% selectivity within 1 min for a hydrogenation reaction) and consistent activity even after 20 cycles for a reduction reaction, considerably outperforming the majority of the conventional photocatalysts. Thus, the proposed strategy establishes a novel method for designing and synthesizing highly efficient and stable catalysts for the convertion of nitroarenes to anilines via chemical reduction.

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Judicious training pattern for superior molecular reorganization energy prediction model Xinxin Niu, Yanfeng Dang, Yajing Sun, Wenping Hu 2023, 81(6): 143-148.  DOI: 10.1016/j.jechem.2023.02.015 Abstract ( 16 )   PDF (1427KB) ( 3 )   Reorganization energy (RE) is closely related to the charge transport properties and is one of the important parameters for screening novel organic semiconductors (OSCs). With the rise of data-driven technology, accurate and efficient machine learning (ML) models for high-throughput screening novel organic molecules play an important role in the boom of material science. Comparing different molecular descriptors and algorithms, we construct a reasonable algorithm framework with molecular graphs to describe the compositional structure, convolutional neural networks to extract material features, and subsequently embedded fully connected neural networks to establish the mapping between features and predicted properties. With our well-designed judicious training pattern about feature-guided stratified random sampling, we have obtained a high-precision and robust reorganization energy prediction model, which can be used as one of the important descriptors for rapid screening potential OSCs. The root-mean-square error (RMSE) and the squared Pearson correlation coefficient (R2) of this model are 2.6 meV and 0.99, respectively. More importantly, we confirm and emphasize that training pattern plays a crucial role in constructing supreme ML models. We are calling for more attention to designing innovative judicious training patterns in addition to high-quality databases, efficient material feature engineering and algorithm framework construction.

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Revealing the effect of electrolyte coordination structures on the intercalation chemistry of batteries Chao Wang, Xianjin Li, Guiming Zhong, Caixia Meng, Shiwen Li, Guohui Zhang, Yanxiao Ning, Xianfeng Li, Qiang Fu 2023, 81(6): 149-156.  DOI: 10.1016/j.jechem.2023.02.038 Abstract ( 6 )   PDF (7409KB) ( 2 )   In-depth understanding of the electrolyte-dependent intercalation chemistry in batteries through direct operando/in situ characterizations is crucial for the development of the high-performance batteries. Herein, taking the Al/graphite battery as a model system, the effect of electrolyte coordination structure on the intercalation processes has been investigated over the batteries with either 1-hexyl-3-methylimidazolium chloride (HMICl)-AlCl3 or 1-ethyl-3-methylimidazolium chloride (EMICl)-AlCl3 ionic liquid electrolyte using operando X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. With a weaker anion-cation interaction in HMI-based electrolyte, the XPS-derived atomic ratio between co-intercalated N and intercalated Al is 0.9, which is lower than 1.6 for EMI-based electrolyte. Attributed to the additional de-solvation process, the batteries with the HMI-based electrolyte show a lower ionic diffusion rate, capacity, and cycling performance, which agree with the operando characterization results. Our findings highlight the critical role of the electrolyte coordination structure on the (co-)intercalation chemistry.

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Upcycling of phosphogypsum waste for efficient zinc-ion batteries Huanwen Wang, Can Luo, Yinyin Qian, Caihong Yang, Xiaojun Shi, Yansheng Gong, Rui Wang, Beibei He, Jun Jin, Aidong Tang, Edison Huixiang Ang, Huaming Yang 2023, 81(6): 157-166.  DOI: 10.1016/j.jechem.2023.02.037 Abstract ( 6 )   PDF (11070KB) ( 1 )   Zinc metal is a promising anode material for next-generation aqueous batteries, but its practical application is limited by the formation of zinc dendrite. To prevent zinc dendrite growth, various Zn2+-conducting but water-isolating solid-electrolyte interphase (SEI) films have been developed, however, the required high-purity chemical materials are extremely expensive. In this work, phosphogypsum (PG), an industrial byproduct produced from the phosphoric acid industry, is employed as a multifunctional protective layer to navigate uniform zinc deposition. Theoretical and experimental results demonstrate that PG-derived CaSO4·2H2O can act as an artificial SEI layer to provide fast channels for Zn2+ transport. Moreover, CaSO4·2H2O could release calcium ions (Ca2+) due to its relatively high Ksp value, which have a higher binding energy than that of Zn2+ on the Zn surface, thus preferentially adsorbing to the tips of the protuberances to force zinc ions to nucleate at inert region. As a result, the Zn@PG anode achieves a high Coulombic efficiency of 99.5% during 500 cycles and long-time stability over 1000 hours at 1 mA cm-2. Our findings will not only construct a low-cost artificial SEI film for practical metal batteries, but also achieve a high-value utilization of phosphogypsum waste.

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Electrocatalytic oxygen evolution activities of metal chalcogenides and phosphides: Fundamentals, origins, and future strategies Xiaolin Hu, Ronghua Wang, Wenlin Feng, Chaohe Xu, Zidong Wei 2023, 81(6): 167-191.  DOI: 10.1016/j.jechem.2023.01.062 Abstract ( 20 )   PDF (26736KB) ( 5 )   The development of inexpensive and efficient electrocatalysts is key to commercializing energy-related electrocatalytic techniques such as water electrolyzers and metal-air batteries. In particular, novel oxygen evolution reaction (OER) pre-catalysts, such as transition metal chalcogenides (TMCs) and phosphides (TMPs), have evolved in recent years from traditional stable OER electrocatalysts, which show superior OER electrocatalytic performance compared with transition metal oxides (TMOs) or (oxy)hydroxides (TMOHs). In this feature article, we summarize recent advances in the development of TMC- and TMP-based OER electrocatalysts, as well as approaches to improve the OER performance in terms of morphology, structure, composition, surface engineering, lattice-strained and in-situ transformation in the electrolysis process. In particular, the electrochemical stability of TMCs and TMPs in alkaline electrolytes and the evolution of morphology, structure and composition under OER conditions are discussed. In the last section, we discuss the challenges that need to be addressed in this specific area of research and the implications for further research.

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Deciphering the critical effect of cathode-electrolyte interphase by revealing its dynamic evolution Zhengfeng Zhang, Changdong Qin, Kuan Wang, Xiao Han, Jinhui Li, Manling Sui, Pengfei Yan 2023, 81(6): 192-199.  DOI: 10.1016/j.jechem.2023.01.046 Abstract ( 11 )   PDF (2599KB) ( 6 )   Cathode electrolyte interphase (CEI) layer plays a crucial role in determining the electrochemical performance of lithium-ion batteries. Limited by the sensitive nature of CEI and the lack of characterization techniques, its dynamic evolution during cycling, its formation mechanism, and its specific impact on battery performance are not yet fully understood. Herein, we systematically investigate the dynamic evolution of CEI layer and its critical effect on the cycling performance of LiCoO2 cathode by diverse characterization techniques. We find that cycling voltage plays a key role in affecting CEI formation and evolution, and a critical potential (4.05 V vs. Li) is identified, which acts as the switching potential between CEI deposition and decomposition. We show that CEI starts deposition in the discharge process when the potential is below 4.05 V, and CEI decomposition occurs when the potential is higher than 4.05 V. When the battery is cycled below such a critical potential, a stable CEI layer is developed, which leads to superior cycling stability. When the battery is cycled above such a critical potential, a CEI-free cathode interface is observed, which also demonstrates good cycle stability. However, when the critical potential falls in the cycling voltage range, CEI deposition and decomposition are repeatedly switched on during cycling, leading to the dynamically unstable CEI layer. The unstable CEI layer causes continuous interfacial reaction and degradation, resulting in battery performance decay. Our work deepens the understanding of the CEI formation and evolution mechanisms, and clarifies the critical effect of CEI layer on cycling performance, which provides new insights into stabilizing the electrode-electrolyte interface for high-performance rechargeable batteries.

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Dielectric polarization in MgFe2O4 coating and bulk doping to enhance high-voltage cycling stability of Na2/3Ni1/3Mn2/3O2 cathode material Xiaoqian Xu, Yizhen Huang, Dan Li, Qichang Pan, Sijiang Hu, Yahao Li, Hongqiang Wang, Youguo Huang, Fenghua Zheng, Qingyu Li 2023, 81(6): 200-211.  DOI: 10.1016/j.jechem.2023.03.001 Abstract ( 9 )   PDF (29443KB) ( 1 )   Charging P2-Na2/3Ni1/3Mn2/3O2 to 4.5 V for higher capacity is enticing. However, it leads to severe capacity fading, ascribing to the lattice oxygen evolution and the P2-O2 phase transformation. Here, the MgFe2O4 coating and Mg, Fe co-doping were constructed simultaneously by Mg, Fe surface treatment to suppress lattice oxygen evolution and P2-O2 phase transformation of P2-Na2/3Ni1/3Mn2/3O2 at deep charging. Through ex-situ X-ray diffraction (XRD) tests, we found that the Mg, Fe bulk co-doping could reduce the repulsion between transition metals and Na+/vacancies ordering, thus inhibiting the P2-O2 phase transition and significantly reducing the irreversible volume change of the material. Meanwhile, the internal electric field formed by the dielectric polarization of MgFe2O4 effectively inhibits the outward migration of oxidized Oα- (α < 2), thereby suppressing the lattice oxygen evolution at deep charging, confirmed by in situ Raman and ex situ XPS techniques. P2-NaNM@MF-3 shows enhanced high-voltage cycling performance with capacity retentions of 84.8% and 81.3% at 0.1 and 1 C after cycles. This work sheds light on regulating the surface chemistry for Na-layered oxide materials to enhance the high-voltage performance of Na-ion batteries.

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Improving the UV-light stability of silicon heterojunction solar cells through plasmon-enhanced luminescence downshifting of YVO4:Eu3+,Bi3+ nanophosphors decorated with Ag nanoparticles Cheng-Kun Wu, Shuai Zou, Chen-Wei Peng, Si-Wei Gu, Meng-Fei Ni, Yu-Lian Zeng, Hua Sun, Xiao-Hong Zhang, Xiao-Dong Su 2023, 81(6): 212-220.  DOI: 10.1016/j.jechem.2023.01.050 Abstract ( 10 )   PDF (2264KB) ( 4 )   The ultraviolet (UV) light stability of silicon heterojunction (SHJ) solar cells should be addressed before large-scale production and applications. Introducing downshifting (DS) nanophosphors on top of solar cells that can convert UV light to visible light may reduce UV-induced degradation (UVID) without sacrificing the power conversion efficiency (PCE). Herein, a novel composite DS nanomaterial composed of YVO4:Eu3+,Bi3+ nanoparticles (NPs) and Ag NPs was synthesized and introduced onto the incident light side of industrial SHJ solar cells to achieve UV shielding. The YVO4:Eu3+,Bi3+ NPs and Ag NPs were synthesized via a sol-gel method and a wet chemical reduction method, respectively. Then, a composite structure of the YVO4:Eu3+,Bi3+ NPs decorated with Ag NPs was synthesized by an ultrasonic method. The emission intensities of the YVO4:Eu3+,Bi3+ nanophosphors were significantly enhanced upon decoration with an appropriate amount of ∼20 nm Ag NPs due to the localized surface plasmon resonance (LSPR) effect. Upon the introduction of LSPR-enhanced downshifting, the SHJ solar cells exhibited an ∼0.54% relative decrease in PCE degradation under UV irradiation with a cumulative dose of 45 kW h compared to their counterparts, suggesting excellent potential for application in UV-light stability enhancement of solar cells or modules.

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Fundamentals, recent developments and prospects of lithium and non-lithium electrochemical rechargeable battery systems Maitri Patel, Kuldeep Mishra, Ranjita Banerjee, Jigar Chaudhari, D.K. Kanchan, Deepak Kumar 2023, 81(6): 221-259.  DOI: 10.1016/j.jechem.2023.02.023 Abstract ( 30 )   PDF (5198KB) ( 21 )   The present and future energy requirements of mankind can be fulfilled with sustained research and development efforts by global scientists. The purpose of this review paper is to provide an overview of the fundamentals, recent advancements on Lithium and non-Lithium electrochemical rechargeable battery systems, and their future prospects. The initial part of this review paper is dedicated to the advancement and challenges faced by the conventional rechargeable batteries, such as lead-acid, Ni-Cd and Ni-MH batteries. The subsequent section of this review focuses on an in-depth analysis of two major categories of rechargeable batteries, namely lithium-based rechargeable battery systems and alternative non-Lithium rechargeable battery systems. The working principle, construction, and a few important research progress on Li-ion, Li-O2, Li-CO2 and Li-S batteries have been highlighted. The recent progress and challenges of the alternate batteries such as Na-ion, Na-S, Mg-ion, K-ion, Al-ion, Al-air, Zn-ion and Zn-air are also discussed in this review. The large gap between theoretical and practical electrochemical values for the alternate battery system must be filled by adopting a series of design architectures followed by modern instrumentation for developing next-generation batteries in a sustainable and efficient way.

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Simultaneous realization of high sulfur utilization and lithium dendrite-free via dual-effect kinetic regulation strategy toward lithium-sulfur batteries Xinqi Zhao, Xiaohong Sun, Ruisong Guo, Song Wang, Fuyun Li, Tingting Li, Wen Zhang, Chunming Zheng, Lingyun An, Leichao Meng, Xudong Hu 2023, 81(6): 260-271.  DOI: 10.1016/j.jechem.2023.01.053 Abstract ( 8 )   PDF (4692KB) ( 2 )   With the high theoretical specific capacity and energy density, lithium-sulfur batteries (LSBs) have been intensively studied as promising candidates for energy storage devices. However, LSBs are largely hindered by inferior sulfur utilization and uncontrollable dendritic growth. Herein, a hierarchical functionalization strategy of stepwise catalytic-adsorption-conversion for sulfur species via the synergetic of the efficiently catalytic host cathode and light multifunctional interlayer has been proposed to concurrently address the issues arising on the dual sides of the LSBs. The multi-layer SnS2 micro-flowers embedded into the natural three-dimensional (3D) interconnected carbonized bacterial cellulose (CBC) nanofibers are fabricated as the sulfur host that provides numerous catalytic sites for the rapid catalytic conversion of sulfur species. Moreover, the distinctive CBC-based SnO2-SnS2 heterostructure network accompanied high conductive carbon nanofibers as the multifunctional interlayer promotes the rapid anchoring-diffusion-conversion of lithium polysulfides, Li+ flux redistribution, and uniform Li deposition. LSBs equipped with our strategy exhibit a high reversible capacity of 1361.5 mA h g-1 at 0.2 C and superior cycling stability with an ultra-low capacity fading of 0.031% per cycle in 1000 cycles at 1.5 C and 0.046% at 3 C. A favorable specific capacity of 859.5 mA h g-1 at 0.3 C is achieved with a high sulfur mass loading of 5.2 mg cm-2, highlighting the potential of practical application. The rational design in this work can provide a feasible solution for high-performance LSBs and promote the development of advanced energy storage devices.

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Recent advances in 3D printed electrode materials for electrochemical energy storage devices Suhail Mubarak, Duraisami Dhamodharan, Hun-Soo Byun 2023, 81(6): 272-312.  DOI: 10.1016/j.jechem.2023.01.037 Abstract ( 19 )   PDF (37797KB) ( 5 )   Electrochemical energy storage (EES) systems like batteries and supercapacitors are becoming the key power sources for attempts to change the energy dependency from inadequate fossil fuels to sustainable and renewable resources. Electrochemical energy storage devices (EESDs) operate efficiently as a result of the construction and assemblage of electrodes and electrolytes with appropriate structures and effective materials. Conventional manufacturing procedures have restrictions on regulating the morphology and architecture of the electrodes, which would influence the performance of the devices. 3D printing (3DP) is an advanced manufacturing technology combining computer-aided design and has been recognised as an artistic method of fabricating different fragments of energy storage devices with its ability to precisely control the geometry, porosity, and morphology with improved specific energy and power densities. The capacity to create mathematically challenging shape or configuration designs and high-aspect-ratio 3D architectures makes 3D printing technology unique in its benefits. Nevertheless, the control settings, interactive manufacturing processes, and protracted post-treatments will affect the reproducibility of the printed components. More intelligent software, sophisticated control systems, high-grade industrial equipment, and post-treatment-free methods are necessary to develop. 3D printed (3DPd) EESDs necessitate dynamic printable materials and composites that are influenced by performance criteria and fundamental electrochemistry. Herein, we review the recent advances in 3DPd electrodes for EES applications. The emphasis is on printable material synthesis, 3DP techniques, and the electrochemical performance of printed electrodes. For the fabrication of electrodes, we concentrate on major 3DP technologies such as direct ink writing (DIW), inkjet printing (IJP), fused deposition modelling (FDM), and stereolithography 3DP (SLA). The benefits and drawbacks of each 3DP technology are extensively discussed. We provide an outlook on the integration of synthesis of emerging nanomaterials and fabrication of complex structures from micro to macroscale to construct highly effective electrodes for the EESDs.

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Deep dive into anionic metal-organic frameworks based quasi-solid-state electrolytes Tingzheng Hou, Wentao Xu 2023, 81(6): 313-320.  DOI: 10.1016/j.jechem.2023.02.048 Abstract ( 15 )   PDF (3452KB) ( 8 )   The development and application of high-capacity energy storage has been crucial to the global transition from fossil fuels to green energy. In this context, metal-organic frameworks (MOFs), with their unique 3D porous structure and tunable chemical functionality, have shown enormous potential as energy storage materials for accommodating or transporting electrochemically active ions. In this perspective, we specifically focus on the current status and prospects of anionic MOF-based quasi-solid-state-electrolytes (anionic MOF-QSSEs) for lithium metal batteries (LMBs). An overview of the definition, design, and properties of anionic MOF-QSSEs is provided, including recent advances in the understanding of their ion transport mechanism. To illustrate the advantages of using anionic MOF-QSSEs as electrolytes for LMBs, a thorough comparison between anionic MOF-QSSEs and other well-studied electrolyte systems is made. With these in-depth understandings, viable techniques for tuning the chemical and topological properties of anionic MOF-QSSEs to increase Li+ conductivity are discussed. Beyond modulation of the MOFs matrix, we envisage that solvent and solid-electrolyte interphase design as well as emerging fabrication techniques will aid in the design and practical application of anionic MOF-QSSEs.

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Ionic liquid electrolytes for sodium-ion batteries to control thermal runaway Keith Sirengo, Aswathy Babu, Barry Brennan, Suresh C. Pillai 2023, 81(6): 321-338.  DOI: 10.1016/j.jechem.2023.02.046 Abstract ( 51 )   PDF (10815KB) ( 14 )   Sodium-ion batteries are expected to be more affordable for stationary applications than lithium-ion batteries, while still offering sufficient energy density and operational capacity to power a significant segment of the battery market. Despite this, thermal runaway explosions associated with organic electrolytes have led to concerns regarding the safety of sodium-ion batteries. Among electrolytes, ionic liquids are promising because they have negligible vapor pressure and show high thermal and electrochemical stability. This review discusses the safety contributions of these electrolyte properties for high-temperature applications. The ionic liquids provide thermal stability while at the same time promoting high-voltage window battery operations. Moreover, apart from cycle stability, there is an additional safety feature attributed to modified ultra-concentrated ionic liquid electrolytes. Concerning these contributions, the following have been discussed, heat sources and thermal runaway mechanisms, thermal stability, the electrochemical decomposition mechanism of stable cations, and the ionic transport mechanism of ultra-concentrated ionic liquid electrolytes. In addition, the contributions of hybrid electrolyte systems consisting of ionic liquids with either organic carbonate or polymers are also discussed. The thermal stability of ionic liquids is found to be the main contributor to cell safety and cycle stability. For high-temperature applications where electrolyte safety, capacity, and cycle stability are important, highly concentrated ionic liquid electrolyte systems are potential solutions for sodium-ion battery applications.

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Multi-branched AgAuPt nanoparticles for efficient electrocatalytic hydrogen evolution: Synergism of tip-enhanced electric field effect and local electric field effect Wenliang Liu, Xiaohan Li, Yuqi Wang, Debo Yang, Zongzhen Guo, Mengfei Liu, Jiqian Wang 2023, 81(6): 339-348.  DOI: 10.1016/j.jechem.2023.02.032 Abstract ( 34 )   PDF (11618KB) ( 21 )   High-curvature multi-noble metallic heterostructures can effectively enhance the electrocatalytic hydrogen evolution performance by utilizing the synergism of tip-enhanced electric field effect and local electric field effect. Herein, we report a two-step synthesis strategy to obtain multi-branched high-curvature AgAuPt heterostructure, firstly amino acids-induced growth of Au branches on Ag nanocubes, and secondly L-AA reduction of H2PtCl6 to incorporate tiny Pt nanoparticles on Au branches. The D-CAgAuPt results in a low overpotential of 38 mV to deliver a cathodic current density of 10 mA cm-2, which is superior to commercial 20% Pt/C (46 mV). The strong electronic interactions between multi-noble metals intrinsically enhance the durability and stability of the catalysts. The intrinsic mechanism of promoting HER performance is investigated and revealed in-depth via the FDTD simulations and DFT calculations. In addition, D-CAgAuPt can also achieve efficient and stable hydrogen evolution in a proton exchange membrane electrolyzer, which has the potential for commercial practical application. This work designs a novel multi-branched high-curvature multi-noble metallic heterostructure, and fully provides insights into the generical and efficient enhancement of electrocatalytic HER performance of multi-noble metallic heterostructures.

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High throughput screening of single atomic catalysts with optimized local structures for the electrochemical oxygen reduction by machine Hao Sun, Yizhe Li, Liyao Gao, Mengyao Chang, Xiangrong Jin, Boyuan Li, Qingzhen Xu, Wen Liu, Mingyue Zhou, Xiaoming Sun 2023, 81(6): 349-357.  DOI: 10.1016/j.jechem.2023.02.045 Abstract ( 13 )   PDF (8732KB) ( 7 )   Single atomic catalysts (SACs), especially metal-nitrogen doped carbon (M-NC) catalysts, have been extensively explored for the electrochemical oxygen reduction reaction (ORR), owing to their high activity and atomic utilization efficiency. However, there is still a lack of systematic screening and optimization of local structures surrounding active centers of SACs for ORR as the local coordination has an essential impact on their electronic structures and catalytic performance. Herein, we systematic study the ORR catalytic performance of M-NC SACs with different central metals and environmental atoms in the first and second coordination sphere by using density functional theory (DFT) calculation and machine learning (ML). The geometric and electronic informed overpotential model (GEIOM) based on random forest algorithm showed the highest accuracy, and its R2 and root mean square errors (RMSE) were 0.96 and 0.21, respectively. 30 potential high-performance catalysts were screened out by GEIOM, and the RMSE of the predicted result was only 0.12 V. This work not only helps us fast screen high-performance catalysts, but also provides a low-cost way to improve the accuracy of ML models.

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Solid polymer electrolytes in all-solid-state lithium metal batteries: From microstructures to properties Zongxi Lin, Ouwei Sheng, Xiaohan Cai, Dan Duan, Ke Yue, Jianwei Nai, Yao Wang, Tiefeng Liu, Xinyong Tao, Yujing Liu 2023, 81(6): 358-378.  DOI: 10.1016/j.jechem.2023.01.063 Abstract ( 12 )   PDF (26880KB) ( 3 )   All-solid-state lithium (Li) metal batteries (ASSLMBs) are considered one of the most promising secondary batteries due to their high theoretical capacity and high safety performance. However, low room-temperature ionic conductivity and poor interfacial stability are two key factors affecting the practical application of ASSLMBs, and our understanding of the mechanisms behind these key problems from microscopic perspective is still limited. In this review, the mechanisms and advanced characterization techniques of ASSLMBs are summarized to correlate the microstructures and properties. Firstly, we summarize the challenges faced by solid polymer electrolytes (SPEs) in ASSLMBs, such as the low room-temperature ionic conductivity and the poor interfacial stability. Secondly, several typical improvement methods of polymer ASSLMBs are discussed, including composite SPEs, ultra-thin SPEs, SPEs surface modification and Li anode surface modification. Finally, we conclude the characterizations for correlating the microstructures and the properties of SPEs, with emphasis on the use of emerging advanced techniques (e.g., cryo-transmission electron microscopy) for in-depth analyzing ASSLMBs. The influence of the microstructures on the properties is very important. Until now, it has been difficult for us to understand the microstructures of batteries. However, some recent studies have demonstrated that we have a better understanding of the microstructures of batteries. Then we suggest that in situ characterization, nondestructive characterization and sub-angstrom resolution are the key technologies to help us further understand the batteries' microstructures and promote the development of batteries. And potential investigations to understand the microstructures evolution and the batteries behaviors are also prospected to expect further reasonable theoretical guidance for the design of ASSLMBs with ideal performance.

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Promoting amorphization of commercial TiO2 upon sodiation to boost the sodium storage performance Tao Li, Ling-Yun Kong, Xue Bai, Yan-Xiang Wang, Yong-Xin Qi 2023, 81(6): 379-388.  DOI: 10.1016/j.jechem.2023.02.021 Abstract ( 7 )   PDF (9988KB) ( 2 )   Anatase TiO2 is a promising anode material for sodium-ion batteries, yet the low electronic and ionic conductivities are the main obstacles for its practical application. Even though the amorphization of TiO2 upon sodiation has already been observed, its underneath mechanisms are not fully elucidated. Herein, a low-cost nitrogen-containing carbon source of polyacrylonitrile is adopted to modify commercial anatase TiO2 by a convenient and nontoxic ball-milling technique combined with subsequent annealing treatment. In particular, the employment of a nitrogen-doping approach accompanied by nitrogen-doped carbon coating, results in a greatly improved conductivity, overall leading to a high reversible capacity of about 260 mA h g-1 at 25 mA g-1, superior rate capabilities, and an ultra-stable capacity of about 186 mA h g-1 after 1600 cycles at 500 mA g-1. Detailed characterizations denote that the improved conductivity as well as the small size of the synthesized TiO2 grains play a key role in the TiO2 amorphization upon sodiation, with the TiO2/C nanocomposite undergoing a complete amorphization in just few cycles. Finally, the irreversible amorphization of TiO2 is confirmed to be a crucial ingredient facilitating the Na+ diffusion kinetics and pseudocapacitive behavior, thus boosting the sodium storage performance.

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Low-dimensional perovskite modified 3D structures for higher-performance solar cells Lili Gao, Ping Hu, ShengzhongLiu 2023, 81(6): 389-403.  DOI: 10.1016/j.jechem.2023.01.061 Abstract ( 23 )   PDF (2985KB) ( 2 )   For solution prepared perovskite solar cells, metal halide perovskite materials with low-dimensional (LD) are flexibly employed in 3D perovskite solar cells to promote efficiency and long-term stability. In this review, the various structures, properties, and applications of LD perovskites are firstly summarized and discussed. To take advantage of LD materials, LD perovskites are introduced in the 3D bulk and/or the interface between the perovskite thin film and the carrier transporting layer to passivate the gain boundary defects while providing the stability advantage of LD materials. Therefore, the preparation methods and crystallization control of the LD perovskite layers are discussed in depth. Then, the combined devices using both LD and 3D components are reviewed on the basis of device design, cell structure, interface charge transfer, energy lever alignment, and synergistic improvement of both efficiency and stability. Finally, the challenges and expectations are speculated for further development of perovskite solar cells.

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Diluted low concentration electrolyte for interphase stabilization of high-voltage LiNi0.5Mn1.5O4 cathode Tao Li, Ziyu Chen, Fengwei Bai, Chengzong Li, Yan Li 2023, 81(6): 404-409.  DOI: 10.1016/j.jechem.2023.02.014 Abstract ( 10 )   PDF (5444KB) ( 5 )   The Co-free LiNi0.5Mn1.5O4 (LNMO) is a promising cathode for lithium-ion batteries owing to its high operating voltage and low costs. However, the synthesis of LNMO is generally time and energy consuming, and its practical application is hindered by the lack of a compatible electrolyte. Herein, a spray pyrolysis-based energy-saving synthesis method as well as a diluted low concentration electrolyte (0.5 M LiPF6 in a mixture of fluoroethylene carbonate/dimethyl carbonate/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (FEC:DMC:TTE, 1:4:5 by volume)) are proposed to address these challenges. Owing to the unique features of the precursor prepared by spray pyrolysis, well-crystallized LNMO single-crystal can be obtained within 1 h calcination at 900 °C. Besides, the fluorinated interphases derived from the diluted low concentration electrolyte not only mitigate the Mn dissolution and Al corrosion at the cathode side, but also suppresses dendritic Li deposition at the anode side, thus enabling stable cycling of both LNMO and Li metal anode. Thus, 30 μm Li | LNMO (1.75 mA h cm-2) cells achieve a high capacity retention (90.9%) after 168 cycles in the diluted low concentration electrolyte.

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Recent advances and key opportunities on in-plane micro-supercapacitors: From functional microdevices to smart integrated microsystems Jieqiong Qin, Hongtao Zhang, Zhi Yang, Xiao Wang, Pratteek Das, Feng Zhou, Zhong-Shuai Wu 2023, 81(6): 410-431.  DOI: 10.1016/j.jechem.2023.01.065 Abstract ( 10 )   PDF (22475KB) ( 5 )   The popularization of portable, implantable and wearable microelectronics has greatly stimulated the rapid development of high-power planar micro-supercapacitors (PMSCs). Particularly, the introduction of new functionalities (e.g., high voltage, flexibility, stretchability, self-healing, electrochromism and photo/thermal response) to PMSCs is essential for building multifunctional PMSCs and their smart self-powered integrated microsystems. In this review, we summarized the latest advances in PMSCs from various functional microdevices to their smart integrated microsystems. Primarily, the functionalities of PMSCs are characterized by three major factors to emphasize their electrochemical behavior and unique scope of application. These include but are not limited to high-voltage outputs (realized through asymmetric configuration, novel electrolyte and modular integration), mechanical resilience that includes various feats of flexibility or stretchability, and response to stimuli (self-healing, electrochromic, photo-responsive, or thermal-responsive properties). Furthermore, three representative integrated microsystems including energy harvester-PMSC, PMSC-energy consumption, and all-in-one self-powered microsystems are elaborately overviewed to understand the emerging intelligent interaction models. Finally, the key perspectives, challenges and opportunities of PMSCs for powering smart microelectronics are proposed in brief.

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Nanoscale transition metal catalysts anchored on perovskite oxide enabling enhanced kinetics of lithium polysulfide redox in lithium-sulfur batteries Wenshuo Hou, Ruilong Li, Zhenhua Wang, Li Fang, Zhe Bai, Tan Wang, Yu Bai, Kening Sun 2023, 81(6): 432-442.  DOI: 10.1016/j.jechem.2023.03.008 Abstract ( 8 )   PDF (11748KB) ( 1 )   To obtain high-performance lithium-sulfur (Li-S) batteries, it is necessary to rationally design electrocatalytic materials that can promote efficient sulfur electrochemical reactions. Herein, the robust heterostructured material of nanoscale transition metal anchored on perovskite oxide was designed for efficient catalytic kinetics of the oxidation and reduction reactions of lithium polysulphide (LiPSs), and verified by density functional theory (DFT) calculations and experimental characterizations. Due to the strong interaction of nanoscale transition metals with LiPSs through chemical coupling, heterostructured materials (STO@M) (M = Fe, Ni, Cu) exhibit excellent catalytic activity for redox reactions of LiPSs. The bifunctional heterostructure material STO@Fe exhibits good rate performance and cycling stability as the cathode host, realizing a high-performance Li-S battery that can maintain stable cycling under rapid charge-discharge cycling. This study presents a novel approach to designing electrocatalytic materials for redox reactions of LiPSs, which promotes the development of fast charge-discharge Li-S batteries.

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MXenes for perovskite solar cells: Progress and prospects Lin Yang, Peng Li, Jiangang Ma, Xintong Zhang, Xiao-Feng Wang, Yichun Liu 2023, 81(6): 443-461.  DOI: 10.1016/j.jechem.2023.02.041 Abstract ( 16 )   PDF (4853KB) ( 7 )   Perovskite solar cells (PSCs) have been developed over the past decade as the forefront of the state-of-the-art photovoltaic technologies owing to their high efficiency and low cost, where nanostructured functional materials play key roles in performance optimization. As a versatile class of two-dimensional (2D) materials, transition metal carbides/nitrides MXenes have gained enormous attentions in PSCs since 2018 due to their superior properties such as excellent metallic conductivity, abundant surface functional groups, tunable work functions, high optical transparency, and mechanical robustness. The explorations of MXenes are of significance in performance promotion and commercialization expansion of devices. As such, this review focuses on the diversified advantages of MXenes, comprehensively summarizing their applications and developments in PSCs as additives, electron/hole transporting layers, interfacial engineering layers, and electrodes in sequence and explaining the relevant mechanisms behind. Simultaneously, the problems emerged from the related studies are considered and the corresponding suggestions like opening up the type of MXenes usage, taking further insight of the modulation of surface termination groups on Fermi levels, understanding the effect on energy level structures of perovskite or other functional layers, and realizing commercialization, etc. are provided for the future in-depth explorations. This review is intended to provide overall perspective of the current status of MXenes and highlight the direction for the future advancements in MXenes design and processes towards efficient, stable, large-area, and low-cost PSCs.

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Bi/Bi3Se4 nanoparticles embedded in hollow porous carbon nanorod: High rate capability material for potassium-ion batteries Zhisong Chen, Yuanji Wu, Xi Liu, Yiwei Zhang, Lichun Yang, Hongyan Li 2023, 81(6): 462-471.  DOI: 10.1016/j.jechem.2023.02.050 Abstract ( 14 )   PDF (14661KB) ( 6 )   Considering their superior theoretical capacity and low voltage plateau, bismuth (Bi)-based materials are being widely explored for application in potassium-ion batteries (PIBs). Unfortunately, pure Bi and Bi-based compounds suffer from severe electrochemical polarization, agglomeration, and dramatic volume fluctuations. To develop an advanced bismuth-based anode material with high reactivity and durability, in this work, the pyrolysis of Bi-based metal-organic frameworks and in-situ selenization techniques have been successfully used to produce a Bi-based composite with high capacity and unique structure, in which Bi/Bi3Se4 nanoparticles are encapsulated in carbon nanorods (Bi/Bi3Se4@CNR). Applied as the anode material of PIBs, the Bi/Bi3Se4@CNR displays fast potassium storage capability with 307.5 mA h g-1 at 20 A g-1 and durable cycle performance of 2000 cycles at 5 A g-1. Notably, the Bi/Bi3Se4@CNR also showed long cycle stability over 1600 cycles when working in a full cell system with potassium vanadate as the cathode material, which further demonstrates its promising potential in the field of PIBs. Additionally, the dual potassium storage mechanism of the Bi/Bi3Se4@CNR based on conversion and alloying reaction has also been revealed by in-situ X-ray diffraction.

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In situ and operando infrared spectroscopy of battery systems: Progress and opportunities Murilo M. Amaral, Carla G. Real, Victor Y. Yukuhiro, Gustavo Doubek, Pablo S. Fernandez, Gurpreet Singh, Hudson Zanin 2023, 81(6): 472-491.  DOI: 10.1016/j.jechem.2023.02.036 Abstract ( 54 )   PDF (16933KB) ( 38 )   In situ and operando infrared spectroscopies are powerful techniques to support the design of novel materials for batteries and the development of new battery systems. These techniques can support the study of batteries by identifying the formation of new species and monitoring electrochemical energy stability. However, few works have employed these techniques, which can be used to investigate various materials, including systems beyond lithium-ion technology, in the research of batteries. Therefore, this review presents a comprehensive overview focusing on the main contributions of in situ and operando infrared spectroscopy for lithium-ion batteries (LIBs) and other battery systems. These techniques can successfully identify the formation of species during the electrolyte reduction, electrode degradation, and the formation of the solid-electrolyte interphase (SEI) layer. From these outcomes, it is possible to conclude that this characterization approach should be employed as a protocol to overcome remaining issues in batteries, consequently supporting battery research. This review aims to be a guide on how infrared spectroscopy can contribute to monitoring battery systems and to lead researchers interested in applying this technique.

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Construction of strong built-in electric field in binary metal sulfide heterojunction to propel high-loading lithium-sulfur batteries Weiming Xiong, Jiande Lin, Huiqun Wang, Sha Li, Junhao Wang, Yuxiang Mao, Xiao Zhan, De-Yin Wu, Li Zhang 2023, 81(6): 492-501.  DOI: 10.1016/j.jechem.2023.03.012 Abstract ( 8 )   PDF (8912KB) ( 3 )   The practical application of lithium-sulfur (Li-S) batteries is greatly hindered by soluble polysulfides shuttling and sluggish sulfur redox kinetics. Rational design of multifunctional hybrid materials with superior electronic conductivity and high electrocatalytic activity, e.g., heterostructures, is a promising strategy to solve the above obstacles. Herein, a binary metal sulfide MnS-MoS2 heterojunction electrocatalyst is first designed for the construction of high-sulfur-loaded and durable Li-S batteries. The MnS-MoS2 p-n heterojunction shows a unique structure of MoS2 nanosheets decorated with ample MnS nanodots, which contributes to the formation of a strong built-in electric field at the two-phase interface. The MnS-MoS2 hybrid host shows strong soluble polysulfide affinity, enhanced electronic conductivity, and exceptional catalytic effect on sulfur reduction. Benefiting from the synergistic effect, the as-derived S/MnS-MoS2 cathode delivers a superb rate capability (643 mA h g-1 at 6 C) and a durable cyclability (0.048% decay per cycle over 1000 cycles). More impressively, an areal capacity of 9.9 mA h cm-2 can be achieved even under an extremely high sulfur loading of 14.7 mg cm-2 and a low electrolyte to sulfur ratio of 2.9 μL mg-1. This work provides an in-depth understanding of the interfacial catalytic effect of binary metal compound heterojunctions on sulfur reaction kinetics.

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Long-range electron synergy over Pt1-Co1/CN bimetallic single-atom catalyst in enhancing charge separation for photocatalytic hydrogen production Man Yang, Jing Mei, Yujing Ren, Jie Cui, Shuhua Liang, Shaodong Sun 2023, 81(6): 502-509.  DOI: 10.1016/j.jechem.2023.03.020 Abstract ( 16 )   PDF (1737KB) ( 16 )   The development of novel single-atom catalysts with optimal electron configuration and economical noble-metal cocatalyst for efficient photocatalytic hydrogen production is of great importance, but still challenging. Herein, we fabricate Pt and Co single-atom sites successively on polymeric carbon nitride (CN). In this Pt1-Co1/CN bimetallic single-atom catalyst, the noble-metal active sites are maximized, and the single-atomic Co1N4 sites are tuned to Co1N3 sites by photogenerated electrons arising from the introduced single-atomic Pt1N4 sites. Mechanism studies and density functional theory (DFT) calculations reveal that the 3d orbitals of Co1N3 single sites are filled with unpaired d-electrons, which lead to the improved visible-light response, carrier separation and charge migration for CN photocatalysts. Thereafter, the protons adsorption and activation are promoted. Taking this advantage of long-range electron synergy in bimetallic single atomic sites, the photocatalytic hydrogen evolution activity over Pt1-Co1/CN achieves 915.8 mmol·g-1Pt·h-1, which is 19.8 times higher than Co1/CN and 3.5 times higher to Pt1/CN. While this electron-synergistic effect is not so efficient for Pt nanoclusters. These results demonstrate the synergistic effect at electron-level and provide electron-level guidance for the design of efficient photocatalysts.

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A semi-immobilized sulfur-rich copolymer backbone with conciliatory polymer skeleton and conductive substrates for high-performance Li-S batteries Tianpeng Zhang, Zihui Song, Jinfeng Zhang, Wanyuan Jiang, Runyue Mao, Borui Li, Siyang Liu, Xigao Jian, Fangyuan Hu 2023, 81(6): 510-518.  DOI: 10.1016/j.jechem.2023.02.031 Abstract ( 9 )   PDF (16391KB) ( 2 )   Sulfur-rich polymers have gained a great deal of attention as the next-generation active materials in lithium-sulfur (Li-S) batteries due to their low cost, environmental compatibility, naturally sulfur uniform dispersion, and distinctive structure covalently bonding with sulfur atoms. However, the poor electrical conductivity and undesirable additional shuttle effect still hinder the commercial application of sulfur-rich polymers. Herein, we report a flexible semi-immobilization strategy to prepare allyl-terminated hyperbranched poly(ethyleneimine)-functionalized reduced graphene oxide (A-PEI-EGO) as sulfur-rich copolymer backbone. The semi-immobilization strategy can effectively reconcile the demand for polymer skeleton and conductive substrates through forming quaternary ammonium groups and reducing oxygen-containing functional groups, resulting in enhanced skeleton adsorption capacity and substrate electronic conductivity, respectively. Furthermore, the stable covalent bonding connection based on polymer molecules (A-PEI) not only completely prevents the additional shuttle effect of lithiation organic molecules and even sulfur-rich oligomers, but provides more inverse vulcanization active sites. As a result, the as-prepared A-PEI-EGO-S cathodes display an initial discharge capacity of 1338 mA h g-1 at a rate of 0.1 C and an outstanding cycling stability of 0.046% capacity decay per cycle over 600 cycles. Even under 6.2 mg cm-2 S-loaded and sparing electrolyte of 6 µL mg-1, the A-PEI-EGO-S cathode can also achieve a superior cycling performance of 98% capacity retention after 60 cycles, confirming its application potential.

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Effect of silicon carbide-based iron catalyst on reactor optimization for non-oxidative direct conversion of methane Eun-hae Sim, Sung Woo Lee, Jin Ju Lee, Seung Ju Han, Jung Ho Shin, Gracia Lee, Sungrok Ko, Kwan-Young Lee, Yong Tae Kim 2023, 81(6): 519-532.  DOI: 10.1016/j.jechem.2023.03.019 Abstract ( 21 )   PDF (5362KB) ( 10 )   The conversion of methane to olefins, aromatics, and hydrogen (MTOAH) can be used to stably obtain hydrocarbons when the effect of the catalytic surface is optimized from the reaction engineering perspective. In this study, Fe/SiC catalysts were packed into a quartz tube reactor. The catalytic surfaces of SiC and the impregnated Fe species decreased the apparent activation energies (Ea) of methane consumption in the blank reactor between 965 and 1020 °C. Consequently, the hydrocarbon yield increased by 2.4 times at 1020 °C. Based on the model reactions of ethane, ethylene, and acetylene mixed with hydrogen in the range of 500-1020 °C, an excess amount of Fe in the reactor favored the C-C coupling reaction over the selective hydrogenation of acetylene; consequently, coke formation was favored over the hydrogenation reaction. The gas-phase reactions and catalyst properties were optimized to increase hydrocarbon yields while reducing coke selectivity. The 0.2Fe catalyst-packed reactor (0.26 wt% Fe) resulted in a hydrocarbon yield of 7.1% and a coke selectivity of <2% when the ratio of the void space of the post-catalyst zone to the catalyst space was adjusted to be ≥2. Based on these findings, the facile approach of decoupling the reaction zone between the catalyst surface and the gas-phase reaction can provide insights into catalytic reactor design, thereby facilitating the scale-up from the laboratory to the commercial scale.

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Vacancy-modified bimetallic FeMoSx/CoNiPx heterostructure array for efficient seawater splitting and Zn-air battery Ansheng Wang, Shan Gao, Jiaguo Yan, Chunning Zhao, Meng Yu, Weichao Wang 2023, 81(6): 533-542.  DOI: 10.1016/j.jechem.2023.02.029 Abstract ( 11 )   PDF (12867KB) ( 1 )   The development of highly efficient OER catalysts with superior durability for seawater electrolysis and Zn-air battery is important but challenging. Herein, the vacancy-modified heterostructured bimetallic FeMoSx/CoNiPx OER electrocatalyst is exploited. Benefiting from the electron redistribution and reaction kinetics modulation resulting from vacancy introduction and heterojunction formation, it yields ultralow OER overpotentials of 196, 276, 303 mV in 1 M KOH and 197, 318, 348 mV in 1 M KOH + seawater at 10, 500, 1000 mA cm-2, respectively, surviving 600 h at 800 mA cm-2 without obvious decay. Further, FeMoSx/CoNiPx-based Zn-air battery not only affords the high peak power density of 214.5 mW cm-2 but also exhibits the small voltage gap of 0.698 V and long lifetime of 500 h at 10 mA cm-2, overmatching overwhelming majority of reported advanced catalysts. It is revealed experimentally that the OER process on rationally designed FeMoSx/CoNiPx follows the adsorbate evolution mechanism and the rate-determining step shifts from *OOH formation in individual building blocks to *OOH deprotonation process in FeMoSx/CoNiPx, providing the directly proof of how the vacancy introduction and heterojunction formation affect the reaction kinetics.

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Exploring the thermal stability of lithium-ion cells via accelerating rate calorimetry: A review Dongxu Ouyang, Mingyi Chen, Jingwen Weng, Kuo Wang, Jian Wang, Zhirong Wang 2023, 81(6): 543-573.  DOI: 10.1016/j.jechem.2023.02.030 Abstract ( 23 )   PDF (27000KB) ( 14 )   Given the importance of lithium-ion cell safety, a comprehensive review on the thermal stability of lithium-ion cells investigated by accelerating rate calorimetry (ARC), is provided in the present work. The operating mechanism of ARC is discussed first, including the usage and the reaction kinetics. Besides that, the thermal stability of the cathode/anode materials at elevated temperatures is revealed by examining the impacts of some significant factors, i.e., the lithium content, particle size, material density, lithium salt, solvent, additive, binder and initial heating temperature. A comparison of the common cathode materials indicates that the presence of Mn and polyanion could significantly enhance the thermal stability of cathode materials, while the doping of Al also helps to restrain the reactivity. Except for their high capacity, some alloy materials demonstrate more competitive safety than traditional carbon anode materials. Furthermore, the thermal behaviors of full cells under abusive conditions are reviewed here. Due to the sensitivity of ARC to the kinetic parameters, a reaction kinetic modeling can be built on the basis of ARC profiles, to predict the thermal behaviors of cell components and cells. Herein, a short-

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Ultralow-voltage hydrogen production and simultaneous Rhodamine B beneficiation in neutral wastewater Xiang Peng, Song Xie, Shijian Xiong, Rong Li, Peng Wang, Xuming Zhang, Zhitian Liu, Liangsheng Hu, Biao Gao, Peter Kelly, Paul K. Chu 2023, 81(6): 574-582.  DOI: 10.1016/j.jechem.2023.03.022 Abstract ( 9 )   PDF (4465KB) ( 3 )   Electrocatalytic water splitting for hydrogen production is hampered by the sluggish oxygen evolution reaction (OER) and large power consumption and replacing the OER with thermodynamically favourable reactions can improve the energy conversion efficiency. Since iron corrodes easily and even self-corrodes to form magnetic iron oxide species and generate corrosion currents, a novel strategy to integrate the hydrogen evolution reaction (HER) with waste Fe upgrading reaction (FUR) is proposed and demonstrated for energy-efficient hydrogen production in neutral media. The heterostructured MoSe2/MoO2 grown on carbon cloth (MSM/CC) shows superior HER performance to that of commercial Pt/C at high current densities. By replacing conventional OER with FUR, the potential required to afford the anodic current density of 10 mA cm-2 decreases by 95%. The HER/FUR overall reaction shows an ultralow voltage of 0.68 V for 10 mA cm-2 with a power equivalent of 2.69 kWh per m3 H2. Additionally, the Fe species formed at the anode extract the Rhodamine B (RhB) pollutant by flocculation and also produce nanosized magnetic powder and beneficiated RhB for value-adding applications. This work demonstrates both energy-saving hydrogen production and pollutant recycling without carbon emission by a single system and reveals a new direction to integrate hydrogen production with environmental recovery to achieve carbon neutrality.

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A Janus separator towards dendrite-free and stable zinc anodes for long-duration aqueous zinc ion batteries Yan Sun, Qinping Jian, Tianshuai Wang, Bin Liu, Yuhan Wan, Jing Sun, Tianshou Zhao 2023, 81(6): 583-592.  DOI: 10.1016/j.jechem.2023.03.007 Abstract ( 11 )   PDF (14397KB) ( 1 )   Critical issues of Zn anodes including undesirable dendrites formation and parasitic reactions severely limit the reversibility and cyclability of Zn anodes. To address these issues, a functional Janus separator with the structure of a mechanically strong sulfonated poly(arylene ether sulfone) (SPAES) dense layer composited on a porous glass fiber (GF) substrate is designed. The SPAES dense layer that faces the Zn anode containing abundant sulfonic acid groups effectively promotes the desolvation process of hydrated Zn ions, guides uniform Zn ion transfer, and blocks anions and water, contributing to dendrite-free and highly reversible Zn plating/stripping cycles, while the porous GF substrate retains high electrolyte uptake. As a result, the Zn symmetric cell with the Janus separator demonstrates an ultralong cycling lifespan of over 2000 h at the areal capacity of 1 mA h cm-2, which is 23-fold superior to that with a pristine glass fiber separator (<90 h). More impressively, the as-prepared Janus separator enables outstanding rate performance and excellent cycling stability of full Zn ion batteries with diverse cathode materials. For instance, when paired with the V2O5 cathode, the full battery with a Janus separator attains an ultrahigh initial specific capacity of 416.3 mA h g-1 and capacity retention of 60% over 450 cycles at 1 A g-1, exceeding that with a glass fiber separator. Hence, this work provides a facile yet effective approach to mitigating the dendrites formation and ameliorating the parasitic reactions of Zn metal anodes for high-performance Zn ion batteries.

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Outstanding performances of graphite||NMC622 pouch cells enabled by a non-inert diluent Qinqin Cai, Hao Jia, Guanjie Li, Zhangyating Xie, Xintao Zhou, Zekai Ma, Lidan Xing, Weishan Li 2023, 81(6): 593-602.  DOI: 10.1016/j.jechem.2023.02.044 Abstract ( 11 )   PDF (7264KB) ( 3 )   Although high salt concentration electrolyte (HCE) can construct effective LiF-rich interphase film and solve the interphasial instability issue of graphite anode, its high cost, high viscosity and poor wettability with electrode materials limit its large-scale application. Generally, localized high concentration electrolyte (LHCE) is obtained by introducing an electrochemically inert diluent into HCE to avoid the above-mentioned problems while maintaining the high interphasial stability of HCE with graphite anode. Unlike traditional inert diluents, 1, 1, 2, 2-tetrafluoroethyl-2, 2, 3, 3-tetrafluropropyl ether (TTE) with electrochemical activity is introduced into propylene carbonate (PC)-based HCE to obtain LHCE-2 (1 M LiPF6, PC:DMC:TTE = 1:1:6.1) herein. Experimental and theoretical simulation results show that TTE participates in the oxidation decomposition and film-forming reaction at the NCM622 cathode surface, conducting a cathode electrolyte interphase (CEI) rich in organic fluorides with excellent electron insulation ability, high structural stability and low interphasial impedance. Thanks to the outstanding interphasial properties induced by LHCE-2, the graphite||NMC622 pouch cell reaches a capacity retention of 80% after 500 cycles at 1 C under room temperature. While at sub-zero temperatures, the capacity released by the cell with LHCE-2 electrolyte is significantly higher than that of HCE and conventional EC-based electrolytes. Meanwhile, the LHCE-2 electrolyte inherits the advantages of TTE flame-resistant, thus improving the safety of the battery.

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Ultrathin poly(cyclocarbonate-ether)-based composite electrolyte reinforced with high-strength functional skeleton Xiaojiao Zheng, Da Xu, Ning Fu, Zhenglong Yang 2023, 81(6): 603-612.  DOI: 10.1016/j.jechem.2023.03.006 Abstract ( 11 )   PDF (10998KB) ( 2 )   Composite polymer electrolytes (CPEs) are considered to be the most promising to break through the performance and safety limitations of traditional lithium-ion batteries because of their excellent electrochemical and mechanical properties. Aiming at the performance limitations of the most common polyether matrix such as poly(ethylene oxide) (PEO), a novel poly(cyclocarbonate-ether) polymer matrix was prepared by in-situ thermal curing, the weaker interaction between its C = O bond and Li+ can promote the rapid transport of Li+. Adding ionic liquid and active filler LLZTO to the matrix can synergistically reduce the crystallinity of matrix and promote the dissociation of lithium salts. In addition, a 3D functional skeleton made of polyacrylonitrile (PAN) and lithium fluoride (LiF) can greatly improve the mechanical strength of polymer matrix after cold pressing, and LiF is also conducive to interface stability. The thickness of the optimal sample (VP6L/CPL) was only 25 μm, and its ionic conductivity, lithium ion transference number, and electrochemical stability window were as high as 7.17 × 10-4 S cm-1 (25 °C), 0.54 and 5.4 V, respectively, while the mechanical strength reaches 6.1 MPa, which can fully inhibit the growth of lithium dendrites. The excellent electrochemical performance and mechanical strength enable the assembled Li|VP6L/CPL|Li battery to be continuously charged for over 200 h and cycled stably for more than 2300 h, and Li|VP6L/CPL|LFP battery can be stably cycled for more than 400 and 550 cycles at 1 C (40 °C) and 0.5 C (25 °C), respectively.

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Bifunctional flame retardant solid-state electrolyte toward safe Li metal batteries Qiang Lv, Yajie Song, Bo Wang, Shangjie Wang, Bochen Wu, Yutong Jing, Huaizheng Ren, Shengbo Yang, Lei Wang, Lihui Xiao, Dianlong Wang, Huakun Liu, Shixue Dou 2023, 81(6): 613-622.  DOI: 10.1016/j.jechem.2023.02.040 Abstract ( 19 )   PDF (11084KB) ( 6 )   Solid polymer electrolytes (SPEs) are one of the most promising alternatives to flammable liquid electrolytes for building safe Li metal batteries. Nevertheless, the poor ionic conductivity at room temperature (RT) and low resistance to Li dendrites seriously hinder the commercialization of SPEs. Herein, we design a bifunctional flame retardant SPE by combining hydroxyapatite (HAP) nanomaterials with N-methyl pyrrolidone (NMP) in the PVDF-HFP matrix. The addition of HAP generates a hydrogen bond network with the PVDF-HFP matrix and cooperates with NMP to facilitate the dissociation of LiTFSI in the PVDF-HFP matrix. Consequently, the prepared SPE demonstrates superior ionic conductivity at RT, excellent fireproof properties, and strong resistance to Li dendrites. The assembled Li symmetric cell with prepared SPE exhibits a stable cycling performance of over 1200 h at 0.2 mA cm-2, and the solid-state LiFePO4||Li cell shows excellent capacity retention of 85.3% over 600 cycles at 0.5 C.

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Sn-doped BiOCl nanosheet with synergistic H+/Zn2+ co-insertion for “rocking chair” zinc-ion battery Yuzhu Qian, Hongrui Wang, Xinni Li, Ting Song, Yong Pei, Li Liu, Bei Long, Xiongwei Wu, Xianyou Wang 2023, 81(6): 623-632.  DOI: 10.1016/j.jechem.2023.03.002 Abstract ( 15 )   PDF (11614KB) ( 14 )   The development of insertion-type anodes is the key to designing “rocking chair” zinc-ion batteries. However, there is rare report on high mass loading anode with high performances. Here, {001}-oriented BiOCl nanosheets with Sn doping are proposed as a promising insertion-type anode. The designs of cross-linked CNTs conductive network, {001}-oriented nanosheet, and Sn doping significantly enhance ion/electron transport, proved via experimental tests and theoretical calculations (density of states and diffusion barrier). The H+/Zn2+ synergistic co-insertion mechanism is proved via ex situ XRD, Raman, XPS, and SEM tests. Accordingly, this optimized electrode delivers a high reversible capacity of 194 mA h g-1 at 0.1 A g-1 with a voltage of ≈0.37 V and an impressive cyclability with 128 mA h g-1 over 2500 cycles at 1 A g-1. It also shows satisfactory performances at an ultrahigh mass loading of 10 mg cm-2. Moreover, the Sn-BiOCl//MnO2 full cell displays a reversible capacity of 85 mA h g-1 at 0.2 A g-1 during cyclic test.

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Lamellar-stacked cobalt-based nanopiles integrated with nitrogen/sulfur co-doped graphene as a bifunctional electrocatalyst for ultralong-term zinc-air batteries Lingxue Meng, Wenwei Liu, Yang Lu, Zhenyi Liang, Ting He, Jinying Li, Haoxiong Nan, Shengxu Luo, Jia Yu 2023, 81(6): 633-641.  DOI: 10.1016/j.jechem.2023.02.035 Abstract ( 9 )   PDF (12978KB) ( 2 )   Sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) kinetics inevitably impede the practical performance of rechargeable zinc-air batteries. Thus, combing the structural designability of transition metal-based electrocatalysts with anionic regulation is highly desired. Herein, mesoporous lamellar-stacked cobalt-based nanopiles with surface-sulfurization modification are elaborately designed and integrated with N/S co-doped graphene to build a robust OER/ORR bifunctional electrocatalyst. The lamellar-stacking mode of mesoporous nanosheets with abundant channels accelerates gas-liquid mass transfer, and partial-sulfurization of cobalt-based matrix surface efficiently improves the intrinsic OER activity. Meanwhile, N/S co-doped graphene further reinforces the ORR active sites while providing a stable conductive skeleton. As expected, this composite electrocatalyst delivers considerable bifunctional activity and stability, with an OER overpotential of 323 mV at 10 mA cm-2 and high durability. When applied in zinc-air batteries, remarkable ultralong-term stability over 4000 cycles and a maximum power density of 150.1 mW cm-2 are achieved. This work provides new insight into structure-composition synergistic design of rapid-kinetics OER/ORR bifunctional electrocatalyst for next-generation metal-air batteries.

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Fast design of catalyst layer with optimal electrical-thermal-water performance for proton exchange membrane fuel cells Jing Yao, Yuchen Yang, Xiongpo Hou, Yikun Yang, Fusheng Yang, Zhen Wu, Zaoxiao Zhang 2023, 81(6): 642-655.  DOI: 10.1016/j.jechem.2023.02.049 Abstract ( 11 )   PDF (10058KB) ( 6 )   The catalyst layer (CL) is the core component in determining the electrical-thermal-water performance and cost of proton exchange membrane fuel cell (PEMFC). Systemic analysis and rapid prediction tools are required to improve the design efficiency of CL. In this study, a 3D multi-phase model integrated with the multi-level agglomerate model for CL is developed to describe the heat and mass transfer processes inside PEMFC. Moreover, a research framework combining the response surface method (RSM) and artificial neural network (ANN) model is proposed to conduct a quantitative analysis, and further a rapid and accurate prediction. With the help of this research framework, the effects of CL composition on the electrical-thermal-water performance of PEMFC are investigated. The results show that the mass of platinum, the mass of carbon, and the volume fraction of dry ionomer has a significant impact on the electrical-thermal-water performance. At the selected points, the sensitivity of the decision variables is ranked: volume fraction of dry ionomer > mass of platinum > mass of carbon > agglomerate radius. In particular, the sensitivity of the volume fraction of dry ionomer is over 50% at these points. Besides, the comparison results show that the ANN model could implement a more rapid and accurate prediction than the RSM model based on the same sample set. This in-depth study is beneficial to provide feasible guidance for high-performance CL design.