Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100, P. R. China.
Qingdao Industrial Energy Storage Research Institute, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, P. R. China.
ACS Appl Mater Interfaces. 2023 Jun 28;15(25):30060-30069. doi: 10.1021/acsami.3c01876. Epub 2023 Jun 14.
Li-rich layered oxide (LLO) cathode materials with mixed cationic and anionic redox reactions display much higher specific capacity than other traditional layered oxide materials. However, the practical specific capacity of LLO during the first cycle in sulfide all-solid-state lithium-ion batteries (ASSLBs) is extremely low. Herein, the capacity contribution of each redox reaction in LLO during the first charging process is qualitatively and quantitatively analyzed by comprehensive electrochemical and structural measurements. The results demonstrate that the cationic redox of the LiTMO (TM = Ni, Co, Mn) phase is almost complete, while the anionic redox of the LiMnO phase is seriously limited due to the sluggish transport kinetics and severe LLO/LiPSCl interface reaction at high voltage. Therefore, the poor intrinsic conductivity and interface stability during the anionic redox jointly restrict the capacity release or delithiation/lithiation degree of LLO during the first cycle in sulfide ASSLBs. This study reveals the origin of the seriously limited anionic redox reaction in LLO, providing valuable guidance for the bulk and interface design of high-energy-density ASSLBs.
富锂层状氧化物（LLO）正极材料具有混合的阳离子和阴离子氧化还原反应，比其他传统层状氧化物材料具有更高的比容量。然而，在硫化物全固态锂离子电池（ASSLBs）中，LLO 在第一个循环中的实际比容量极低。在此，通过综合电化学和结构测量，定性和定量地分析了 LLO 在第一个充电过程中每个氧化还原反应的容量贡献。结果表明，LiTMO（TM = Ni、Co、Mn）相的阳离子氧化还原几乎完全，而 LiMnO 相的阴离子氧化还原由于在高压下传输动力学缓慢和 LLO/LiPSCl 界面反应严重受限而受到严重限制。因此，在阴离子氧化还原过程中较差的本征电导率和界面稳定性共同限制了 LLO 在硫化物 ASSLBs 中的第一个循环中的容量释放或脱锂/嵌锂程度。本研究揭示了 LLO 中阴离子氧化还原反应受到严重限制的原因，为高能密度 ASSLBs 的体相和界面设计提供了有价值的指导。
