Poly(ethylene oxide)(PEO)-based solid poly-mer electrolyte(SPE)is considered as a promising solid-state electrolyte for all-solid-state lithium batteries(ASSLBs).Nev-ertheless,the poor interfacial stability with high-voltage cath-ode materials(e.g.,LiCoO2)restricts its application in high energy density solid-state batteries.Herein,high-voltage stable Li3AIF6 protective layer is coated on the surface of LiCoO2 particle to improve the performance and investigate the fail-ure mechanism of PEO-based ASSLBs.The phase transition unveils that chemical redox reaction occurs between the highly reactive LiCoO2 surface and PEO-based SPE,resulting in structure collapse of LiCoO2,hence the poor cycle performance of PEO-based ASSLBs with LiCoO2 at charging voltage of 4.2 V vs Li/Li+.By sharp contrast,no obvious structure change can be found at the surface of Li3AlF6-coated LiCoO2,and the original layered phase was well retained.When the charging voltage reaches up to 4.5 V vs Li/Li+,the intensive electrochemical decomposition of PEO-based SPE occurs,leading to the constant increase of cell impedance and directly causing the poor performance.This work not only provides important supplement to the failure mechanism of PEO-based batter-ies with LiCoO2,but also presents a universal strategy to retain structure stability of cathode-electrolyte interface in high-voltage ASSLBs.

Jiawen Li;Yuchen Ji;Haoran Song;Shiming Chen;Shouxiang Ding;Bingkai Zhang;Luyi Yang;Yongli Song;Feng Pan

School of Advanced Material,Peking University Shenzhen Graduate School,Shenzhen 518055,People's Republic of China;Guangzhou Key Laboratory of Clean Transportation Energy Chemistry,School of Chemical Engineering and Light Industry,Guangdong University of Technology,Guangzhou 51006,People's Republic of China

纳微快报（英文）

[1]Jiawen Li;Yuchen Ji;Haoran Song;Shiming Chen;Shouxiang Ding;Bingkai Zhang;Luyi Yang;Yongli Song;Feng Pan-.Insights Into the Interfacial Degradation of High-Voltage All-Solid-State Lithium Batteries)[J].纳微快报（英文）,2022(12):1-13

ertheless,Li3AIF6,Li3AlF6

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