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2020, Vol. 44, No. 5　Online: 2020-05-15

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Test factors affecting the performance of zinc-air battery Dian Jiao, Ziang Ma, Jisi Li, Yajing Han, Jing Mao, Tao Ling, Shizhang Qiao 2020, 44(5): 1-7.  DOI: 10.1016/j.jechem.2019.09.008 摘要 ( 21 )   Zinc-air batteries provide a great potential for future large-scale energy storage. We assess the test factors that mainly affect the measured power density of the zinc-air battery. By fitting the polarization curves of the zinc-air batteries, we reveal the effect of testing parameters (electrode distance, electrolyte concentration, and oxygen flux) and preparation of catalysts ink on the activation, ohm, and concentration polarizations of the zinc-air battery. Finally, recommendations on evaluating the potentials of non-noblemetal electrocatalysts for applications in zinc-air batteries were given

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Interface effect on promoting reversible conversion for Na2Se in the metal selenide as sodium ion batteries Tianshuai Wang, Jiewen Xiao, Xiyu Cao, Yanchen Fan, Qianfan Zhang 2020, 44(5): 8-12.  DOI: 10.1016/j.jechem.2019.09.012 摘要 ( 28 )

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Unlock the potential of Li4Ti5O12 for high-voltage/long-cycling-life and high-safety batteries: Dual-ion architecture superior to lithium-ion storage Xiaoyuan Shi, Shansheng Yu, Ting Deng, Wei Zhang, Weitao Zheng 2020, 44(5): 13-18.  DOI: 10.1016/j.jechem.2019.09.015 摘要 ( 108 )   Li4Ti5O12 (LTO) has drawn great attention due to its safety and stability in lithium-ion batteries (LIBs). However, high potential plateau at 1.5 V vs. Li reduces the cell voltage, leading to a limited use of LTO. Dual-ion batteries (DIBs) can achieve high working voltage due to high intercalation potential of cathode. Herein, we propose a DIB configuration in which LTO is used as anode and the working voltage was 3.5 V. This DIB achieves a maximum specific energy of 140 Wh/kg at a specific power of 35 W/kg, and the specific power of 2933 W/kg can be obtained with a remaining specific energy of 11 Wh/kg. Traditional LIB material shows greatly improved properties in the DIB configuration. Thus, reversing its disadvantage leads to upgraded performance of batteries. Our configuration has also widened the horizon of materials for DIBs.

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Existence of Al2F7- in molten MF-AlF3 (M = K, Cs) systems as determined by Raman spectroscopy and structural simulation Ming Lin, Xianwei Hu, Zhongning Shi, Bingliang Gao, Jiangyu Yu, Zhaowen Wang 2020, 44(5): 19-23.  DOI: 10.1016/j.jechem.2019.09.009 摘要 ( 5 )   The molten mixtures of alkali metal fluorides and aluminum fluoride are applied as aluminum electrolytes or brazing fluxes. However, the presence of Al2F7- in such molten systems is disputed. In the present study, MF-AlF3 (M=K, Cs) systems with molar ratios < 1 were studied by in-situ Raman spectroscopy and molecular simulation. The results show that, in addition to AlF63-, AlF52-, and AlF4-, the systems also contained Al2F7-. The characteristic bands in the Raman spectra belonging to Al2F7- were located at about 225 cm-1, 315 cm-1, 479 cm-1, and 720 cm-1. There are two possible structures of Al2F7-, which belong to the D3d and D3h point groups. Both of these structures are linear, and their single-point energies were found to differ by only 0.31 kcal/mol.

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First-principles investigation of β-Ge3N4 loaded with RuO2 cocatalyst for photocatalytic overall water splitting Yanxia Ma, Miaomiao Wang, Xin Zhou 2020, 44(5): 24-32.  DOI: 10.1016/j.jechem.2019.09.013 摘要 ( 4 )   β-Ge3N4 loaded with nanoparticulate RuO2 as a cocatalyst is the first successful non-oxide photocatalyst for overall water splitting. To get an insight into the working mechanism of this particular photocatalytic system, we have calculated geometrical structures of low-index surfaces for β-Ge3N4. Analysis of surface energies indicates that the most preferentially exposed surface is (100). The band gap of surface is narrower than that of bulk due to the dangling bonds. Dissociative water adsorption on (100) surface is thermodynamically favorable. The adsorption behavior of (RuO2)n (n=2, 3, and 4) clusters on the β-Ge3N4(100) surface has been explored. It is found that all the clusters bind to (100) surface strongly by forming interfacial bonds so that the adsorptions are exothermic processes. The calculation on density of states for β-Ge3N4(100) surface loaded with (RuO2)n clusters reveals that photo-induced electrons tend to accumulate on (RuO2)n clusters and holes tend to stay in β-Ge3N4. Based on the theoretical indication of Type-II staggered band alignment, we have proposed that in photocatalytic water splitting reaction, oxygen evolution reaction is inclined to occur on the surface of β-Ge3N4 while hydrogen evolution reaction is apt to occur on (RuO2)n clusters. In a word, loading RuO2 nanoparticles as a reduction cocatalyst benefits the charge separation in β-Ge3N4. Furthermore, attaching (RuO2)n clusters onto β-Ge3N4(100) surface results in the redshift of absorption edge and the increase of absorption intensity. Our calculations have reasonably explained the experimental observation on the decomposition of water into H2 and O2 after loading RuO2 cocatalyst in β-Ge3N4 photocatalyst.

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A polyethylene microsphere-coated separator with rapid thermal shutdown function for lithium-ion batteries Chongrong Zhang, Hui Li, Shixuan Wang, Yuliang Cao, Hanxi Yang, Xinping Ai, Faping Zhong 2020, 44(5): 33-40.  DOI: 10.1016/j.jechem.2019.09.017 摘要 ( 33 )   Thermal runaway is the main factor contributing to the unsafe behaviors of lithium-ion batteries (LIBs) in practical applications. The application of separators for the thermal shutdown has been proven as an effective approach to protecting LIBs from thermal runaway. In this work, we developed a thermal shutdown separator by coating a thin layer of low-density polyethylene microspheres (PM) onto a commercial porous polypropylene (PP) membrane and investigated the thermal response behaviors of the as-prepared PM/PP separator in LIBs. The structural and thermal analysis results revealed that the coated PM layer had a porous structure, which facilitated the occurrence of normal charge-discharge reactions at ambient temperature, although it could melt completely and fuse together within very short time periods:3 s at 110℃ and 1 s at 120℃, to block off the pores of the PP substrate, thereby cutting off the ion transportation between the electrodes and interrupting the battery reaction. Consequently, the PM/PP separator exhibits very similar electrochemical performance to that of a conventional separator at ambient temperature. However, it performs a rapid thermal shutdown at an elevated temperature of ~110℃, thus controlling the temperature rise and maintaining the cell in a safe status. Due to its synthetic simplicity and low cost, this separator shows promise for possible application in building safe LIBs.

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Tailored PEDOT:PSS hole transport layer for higher performance in perovskite solar cells: Enhancement of electrical and optical properties with improved morphology Khan Mamun Reza, Ashim Gurung, Behzad Bahrami, Sally Mabrouk, Hytham Elbohy, Rajesh Pathak, Ke Chen, Ashraful Haider Chowdhury, Md Tawabur Rahman, Steven Letourneau, Hao-Cheng Yang, Gopalan Saianand, Jeffrey W. Elam, Seth B. Darling, Qiquan Qiao 2020, 44(5): 41-50.  DOI: 10.1016/j.jechem.2019.09.014 摘要 ( 31 )   Precise control over the charge carrier dynamics throughout the device can result in outstanding performance of perovskite solar cells (PSCs). Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is the most actively studied hole transport material in p-i-n structured PSCs. However, charge transport in the PEDOT:PSS is limited and inefficient because of its low conductivity with the presence of the weak ionic conductor PSS. In addition, morphology of the underlying PEDOT:PSS layer in PSCs plays a crucial role in determining the optoelectronic quality of the active perovskite absorber layer. This work is focused on realization of a non-wetting conductive surface of hole transport layer suitable for the growth of larger perovskite crystalline domains. This is accomplished by employing a facile solventengineered (ethylene glycol and methanol) approach resulting in removal of the predominant PSS in PEDOT:PSS. The consequence of acquiring larger perovskite crystalline domains was observed in the charge carrier dynamics studies, with the achievement of higher charge carrier lifetime, lower charge transport time and lower transfer impedance in the solvent-engineered PEDOT:PSS-based PSCs. Use of this solventengineered treatment for the fabrication of MAPbI3 PSCs greatly increased the device stability witnessing a power conversion efficiency of 18.18%, which corresponds to ～37% improvement compared to the untreated PEDOT:PSS based devices.

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Separator coatings as efficient physical and chemical hosts of polysulfides for high-sulfur-loaded rechargeable lithium-sulfur batteries Masud Rana, Ming Li, Qiu He, Bin Luo, Lianzhou Wang, Ian Gentle, Ruth Knibbe 2020, 44(5): 51-60.  DOI: 10.1016/j.jechem.2019.08.017 摘要 ( 23 )   Lithium-sulfur batteries (LSBs) are promising alternative energy storage devices to the commercial lithium-ion batteries. However, the LSBs have several limitations including the low electronic conductivity of sulfur (5×10-30 S cm-1), associated lithium polysulfides (PSs), and their migration from the cathode to the anode. In this study, a separator coated with a Ketjen black (KB)/Nafion composite was used in an LSB with a sulfur loading up to 7.88 mg cm-2 to mitigate the PS migration. A minimum specific capacity (Cs) loss of 0.06% was obtained at 0.2 C-rate at a high sulfur loading of 4.39 mg cm-2. Furthermore, an initial areal capacity up to 6.70 mA h cm-2 was obtained at a sulfur loading of 7.88 mg cm-2. The low Cs loss and high areal capacity associated with the high sulfur loading are attributed to the large surface area of the KB and sulfonate group (SO3-) of Nafion, respectively, which could physically and chemically trap the PSs.

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Biomass-derived nitrogen-doped hierarchical porous carbon as efficient sulfur host for lithium-sulfur batteries Qinghuiqiang Xiao, Gaoran Li, Minjie Li, Ruiping Liu, Haibo Li, Pengfei Ren, Yue Dong, Ming Feng, Zhongwei Chen 2020, 44(5): 61-67.  DOI: 10.1016/j.jechem.2019.09.004 摘要 ( 54 )   Lithium-sulfur (Li-S) battery is a potential energy storage technology with high energy density and low cost. However, the gap between theoretical expectation and practical performance limits its wide implementation. Herein, we report a nitrogen-doped porous carbon derived from biomass pomelo peel as sulfur host material for Li-S batteries. The hierarchical porous architecture and the polar surface introduced by N-doping render a favorable combination of physical and chemical sulfur confinements as well as an expedite electron/ion transfer, thus contributing to a facilitated and stabilized sulfur electrochemistry. As a result, the corresponding sulfur composite electrodes exhibit an ultrahigh initial capacity of 1534.6 mAh g-1, high coulombic efficiency over 98% upon 300 cycles, and decent rate capability up to 2 C. This work provides an economical and effective strategy for the fabrication of advanced carbonaceous sulfur host material as well as the significant improvement of Li-S battery performance.

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Homogenous charge distribution by free-standing porous structure for dendrite-free Li metal anode Danmiao Kang, Kun Tang, Joonho Koh, Wenbin Liang, John P. Lemmon 2020, 44(5): 68-72.  DOI: 10.1016/j.jechem.2019.09.005 摘要 ( 5 )   Lithium metal has a high theoretical capacity of 3860 mAh g-1 and a low electrochemical potential (-3.04 V vs. H2/H+). Hence, using a lithium anode significantly improves the energy density of a secondary battery. However, the lithium dendrites generated on the lithium anode during the platingdissolution process significantly reduce its cycling life and safety. Here, we provide a simple method for lithium anode protection, by applying a free-standing porous carbon film with a high specific surface area to reduce the local current density and obtain a homogenous ion distribution. The protected lithium anode has a long cycle life over 1000 h when cycled at 3 mA cm-2 with a lithium capacity of 2.5 mAh cm-2. Moreover, the deposited lithium has a smoother surface than Li anode without carbon protection. This study will promote the wide application of Li-metal-based batteries with high safety levels.

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Three dimensional porous frameworks for lithium dendrite suppression Shuyan Ni, Shuangshuang Tan, Qinyou An, Liqiang Mai 2020, 44(5): 73-89.  DOI: 10.1016/j.jechem.2019.09.031 摘要 ( 13 )   Lithium metal is a promising anode material owing to its very low electrochemical potential and ultrahigh specific capacity. However, the growth of lithium dendrites could result in a short lifespan, low coulombic efficiency, and potential safety hazards during the progress of lithium plating/stripping. These factors drastically hinder its application in lithium metal batteries. This review focuses on the use of three dimensional (3D) porous host frameworks to improve Li plating/stripping behaviors, accommodate the change in volume, and suppress or block lithium dendrite growth. Various 3D porous frameworks, including the conductive carbon-based, metal-based, and lithiophilic inorganic-compound frameworks are introduced and summarized in detail. The particular functions, relative developments, and optimized strategies of various 3D porous frameworks for lithium deposition/dissolution behaviors are discussed. Moreover, the challenges and promising developments in the field of Li metal anodes will be discussed at the end of this review.

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MOF-derived Co9S8/MoS2 embedded in tri-doped carbon hybrids for efficient electrocatalytic hydrogen evolution Tian-Tian Chen, Rui Wang, Lin-Ke Li, Zhong-Jun Li, Shuang-Quan Zang 2020, 44(5): 90-96.  DOI: 10.1016/j.jechem.2019.09.018 摘要 ( 9 )   Metal-organic framework (MOF) derived hybrid materials have been developed as an efficient non-noblemetal electrocatalysts for clean energy conversion systems. In this work, a Co-based MOF containing nitrogen and oxygen heteroatoms (Co-NOMOF) mixed with the thiomolybdate[Mo3S13]2- nanoclusters was used to prepare the N, S, O-doped carbon encapsulating Co9S8 and MoS2 (Co9S8/MoS2@NSOC) nanocomposite by one-step pyrolysis. The Co9S8/MoS2@NSOC nanocomposite exhibited remarkable catalytic performance for hydrogen evolution reaction (HER) with overpotential of 194 and 233 mV in 1 M KOH and 0.5 M H2SO4 solution under 10 mA cm-2, respectively, which was ascribed to the multiheteroatom-doped hierarchical porous carbon matrix and the synergistic effect of intrinsic activity of Co9S8 and MoS2. This work provides new opportunity for developing highly efficient non-precious metal electrochemical catalysts.

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Formation of hierarchical Fe7Se8 nanorod bundles with enhanced sodium storage properties Wenzhi Tian, Wenzhe Ma, Zhenyu Feng, Fang Tian, Haibo Li, Jing Liu, Shenglin Xiong 2020, 44(5): 97-105.  DOI: 10.1016/j.jechem.2019.08.021 摘要 ( 2 )   Ordered hierarchical architectures are attractive candidates for electrochemical energy storage applications. Herein, a facile self-template strategy is applied to prepare Fe7Se8 architectures with a monolithic structure via a self-synthesized single precursor and subsequent calcination at high temperature. With the support of oleylamine, the precursor is structurally targeted to engineer the Fe7Se8 microstructure, featuring nanorod bundles arranged along the longitudinal direction. Because of their ordered hierarchical structure, the Fe7Se8 nanorod bundles deliver a high reversible capacity of 300 mAh g-1 at 0.5 A g-1, along with exceptional rate capability up to 20 A g-1 and long-term cycle life over 8000 cycles, which represents the highest stability of Fe7Se8 anodes for sodium-ion batteries reported to date. The feasibility of the present strategy to prepare metal selenide structures highlights its promising potential for the rational and effective engineering of electrode materials responsible for the electrochemical performance of energy storage systems.

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Lignin derived multi-doped (N, S, Cl) carbon materials as excellent electrocatalyst for oxygen reduction reaction in proton exchange membrane fuel cells Yixing Shen, Yuhang Li, Guangxing Yang, Qiao Zhang, Hong Liang, Feng Peng 2020, 44(5): 106-114.  DOI: 10.1016/j.jechem.2019.09.019 摘要 ( 15 )   Nowadays, hierarchically macro-/meso-/microporous 3D carbon materials have been paid more attention due to their imaginative application potential in specific electrochemistry. Here, we report a dualtemplate strategy using eutectic NaCl/ZnCl2 melt as airtight and swelling agent to obtain 3D mesoporous skeleton structured carbon from renewable lignin. The prepared lignin-derived biocarbon material (LN-3-1) has a high specific surface area (1289 m2 g-1), a large pore volume (2.80 cm3 g-1), and a well-connected and stable structure. LN-3-1 exhibits extremely high activity and stability in acidic medium for oxygen reduction reaction (ORR), superior to Pt/C catalyst and most non noble-metal catalysts reported in recent literatures. The prepared carbon material was used as a cathode catalyst to assemble a H2-O2 single fuel cell, and its excellent catalytic performance has been confirmed with the maximum power density of 779 mW cm-2, which is one of the highest power densities among non-metallic catalysts so far. Density functional theory (DFT) calculations indicate that the synergy of chlorine and nitrogen reconciles the intermediate adsorption energies, leading to an appropriate theoretical ORR onset potential. We develop a cost-effective and highly efficient method to prepare biocarbon catalyst for ORR in proton-exchange membrane fuel cells.

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Benzothiadiazole-based hole transport materials for high-efficiency dopant-free perovskite solar cells: Molecular planarity effect Xiang Zhou, Fantai Kong, Yuan Sun, Yin Huang, Xianxi Zhang, Rahim Ghadari 2020, 44(5): 115-120.  DOI: 10.1016/j.jechem.2019.09.020 摘要 ( 18 )   A new benzothiadiazole-based D-A-D hole transport material (DTBT) has been designed and synthesized with a more planar structure by introducing of thiophene bridges. The results indicate a lower band gap and quite higher hole mobility for the DTBT. Furthermore, the enhancement in molecular planarity with simple thiophene unit increases the hole mobility of DTBT (8.77×10-4 cm2 V-1. s-1) by about 40%. And when DTBT is used as hole transport material in perovskite solar cells, the photoelectric conversion efficiency of the corresponding dopant-free devices is also significantly improved compared with that of the conventional BT model molecule without thiophene. In terms of device stability, DTBT-based devices show a favorable long-term stability, which keep 83% initial efficiency after 15 days. Therefore, the introducing of thiophene bridges in D-A-D typed HTMs can improve the molecular planarity effectively, thereby increasing the hole mobility and improving device performance.

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Facile preparation of N-doped corncob-derived carbon nanofiber efficiently encapsulating Fe2O3 nanocrystals towards high ORR electrocatalytic activity Wei Yan, Yanling Wu, Yanli Chen, Qi Liu, Kang Wang, Ning Cao, Fangna Dai, Xiyou Li, Jianzhuang Jiang 2020, 44(5): 121-130.  DOI: 10.1016/j.jechem.2019.09.002 摘要 ( 8 )   Facile preparation of cost-effective and durable porous carbon-supported non-precious-metal/nitrogen electrocatalysts for oxygen reduction reaction (ORR) is extremely important for promoting the commercialized applications of such catalysts. In this work, the FeCl3-containing porphyrinato iron-based covalent porous polymer (FeCl3·FePor-CPP) was fabricated in-situ onto porous corncob biomass supports via a simple one-pot method. Subsequent thermal-reduction pyrolysis at 700℃-900℃ with CO2 gas as an activating agent resulted in Fe2O3-decorated and N-doped graphitic carbon composite Fe2O3@NC&bio-C with a high degree of graphitization of Fe-involved promotion during pyrolysis (Fe2O3=FeCl3·FePor-CPP derived Fe2O3; NC=N-doped graphene analog; bio-C=the corncob-derived hierarchically porous graphitic biomass carbon framework). The derived α-Fe2O3 and γ-Fe2O3 nanocrystals (5-10 nm particle diameter) were all immobilized on the N-doped bio-C micro/nanofibers. Notably, the Fe2O3@NC&bio-C obtained at the pyrolysis temperature of 800℃ (Fe2O3@NC&bio-C-800), exhibited unusual ORR catalytic efficiency via a 4-electron pathway with the onset and half-wave potentials of 0.96 V and 0.85 V vs. RHE, respectively. In addition, Fe2O3@NC&bio-C-800 also exhibited a high and stable limiting current density of -6.0 mA cm-2, remarkably stability (larger than 91% retention after 10000s), and good methanol tolerance. The present work represents one of the best results for iron-based biomass material ORR catalysts reported to date. The high ORR activity is attributed to the uniformly distributed α-Fe2O3 and γ-Fe2O3 nanoparticles on the N-enriched carbon matrix with a large specific surface area of 772.6 m2 g-1. This facilitates favor faster electron movement and better adsorption of oxygen molecules on the surface of the catalyst. Nevertheless, comparative studies on the structure and ORR catalytic activity of Fe2O3@NC&bioC-800 with Fe2O3@bio-C-800 and NC&bio-C-800 clearly highlight the synergistic effect of the coexisting Fe2O3 nanocrystals, NC, and bio-C on the ORR performance.

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Role of local coordination in bimetallic sites for oxygen reduction: A theoretical analysis Yuqi Yang, Hao Zhang, Zhaofeng Liang, Yaru Yin, Bingbao Mei, Fei Song, Fanfei Sun, Songqi Gu, Zheng Jiang, Yuen Wu, Zhiyuan Zhu 2020, 44(5): 131-137.  DOI: 10.1016/j.jechem.2019.08.009 摘要 ( 6 )   Understanding of the oxygen reduction reaction (ORR) mechanism for single atom catalysts is pivotal for the rational design of non-precious metal cathode materials and the commercialization of fuel cells. Herein, a series of non-precious metal electrocatalysts based on nitrogen-doped bimetallic (Fe and Co) carbide were modeled by density functional theory calculations to predict the corresponding reaction pathways. The study elucidated prior oxygen adsorption on the Fe atom in the dual site and the modifier role of Co atoms to tune the electronic structures of Fe. The reaction activity was highly correlated with the bimetallic center and the coordination environment of the adjacent nitrogen. Interestingly, the preadsorption of *OH resulted in the apparent change of metal atoms' electronic states with the d-band center shifting toward the Fermi level, thereby boosting reaction activity. The result should help promote the fundamental understanding of active sites in ORR catalysts and provide an effective approach to the design of highly efficient ORR catalysts on an atomic scale.

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Operando X-ray diffraction analysis of the degradation mechanisms of a spinel LiMn2O4 cathode in different voltage windows Fakui Luo, Congcong Wei, Chi Zhang, Hui Gao, Jiazheng Niu, Wensheng Ma, Zhangquan Peng, Yanwen Bai, Zhonghua Zhang 2020, 44(5): 138-146.  DOI: 10.1016/j.jechem.2019.09.011 摘要 ( 5 )   The understanding of reaction mechanisms of electrode materials is of significant importance for the development of advanced batteries. The LiMn2O4 cathode has a voltage plateau around 2.8 V (vs. Li+/Li), which can provide an additional capacity for Li storage, but it suffers from a severe capacity degradation. In this study, operando X-ray diffraction is carried out to investigate the structural evolutions and degradation mechanisms of LiMn2O4 in different voltage ranges. In the range of 3.0-4.3 V (vs. Li+/Li), the LiMn2O4 cathode exhibits a low capacity but good cycling stability with cycles up to 100 cycles and the charge/discharge processes are associated with the reversible extraction/insertion of Li+ from/into LixMn2O4 (0 ≤ x ≤ 1). In the range of 1.4-4.4 V (vs. Li+/Li), a capacity higher than 200 mAh/g is achieved, but it rapidly decays during the cycling. The voltage plateau around 2.8 V (vs. Li+/Li) is related to the transformation of the cubic LiMn2O4 phase to the tetragonal Li2Mn2O4 phase, which leads to the formation of cracks as well as the performance degradation.

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Continuous electrodeposition of silicon and germanium micro/nanowires from their oxides precursors in molten salt Xingli Zou, Li Ji, Zhongya Pang, Qian Xu, Xionggang Lu 2020, 44(5): 147-153.  DOI: 10.1016/j.jechem.2019.09.016 摘要 ( 10 )   In recent years, silicon (Si) and germanium (Ge) materials have been considered as promising highperformance anode materials for lithium-ion batteries due to their high theoretical capacities. It is of great importance to design and synthesize micro/nanostructured Si and Ge materials. In this work, we demonstrated that Si, Ge and SiGe micro/nanowires can be continuously synthesized from their oxides precursors through molten salt electrodeposition. The electrochemical synthesis processes have been investigated systematically, and the deposited Si, Ge and SiGe micro/nanowires have been characterized and compared. The results show that the micro/nanostructured Si and Ge materials with tunable morphology can be facilely and continuously produced via molten salt electrodeposition. The electrodeposition process generally includes calcium oxide-assisted dissolution and electrodeposition processes, and the morphologies of the deposited Si and Ge products can be controlled by varying conditions. Si micro/nanowires, Si films, Ge micro/nanowires, and Ge particles can be continuously synthesized in a controlled manner.

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New redox-mediating polymer binder for enhancing performance of Li-S batteries Soochan Kim, Misuk Cho, Chalathorn Chanthad, Youngkwan Lee 2020, 44(5): 154-161.  DOI: 10.1016/j.jechem.2019.09.001 摘要 ( 23 )   Lithium-sulfur (Li-S) batteries are promising energy storage devices owing to their high energy density and the low cost of sulfur. However, they are still far from being applied commercially because of the detrimental capacity fade caused by the dissolution of lithium polysulfide (LPS) in liquid electrolyte. In this study, we introduced a new polymer binder having a redox-mediating function that assists in the reduction of soluble LPS to Li2S at the cathode to suppress the shuttle effect as well as enhance sulfur utilization. An amine group containing benzo(ghi)perylene imide (BPI) was synthesized and grafted onto poly(acrylic acid) to produce a redox-mediating polymer binder. An Li-S cell fabricated using the new redox-mediating polymer binder demonstrated a capacity decay retention of 0.036% per cycle up to 500 cycles at 0.5 C with a coulombic efficiency of 98%.