Surface reconstruction layer boosting interfacial stability of LiCoO₂/Li₆PS₅Cl in bulk all-solid-state Li batteries

The interfacial compatibility between cathode materials and sulfide solid-electrolytes (SEs) is a critical factor affecting the electrochemical performance of all-solid-state lithium-ion batteries (ASSLBs). This work presents a gas-solid interface reduction reaction (GSIRR) to reduce surface oxygen reactivity by inducing a surface reconstruction layer through in situ generated CoO/Li2CO3 on the LiCoO2 cathode surface. Experimental results demonstrate that the surface reconstruction layer effectively suppresses interfacial side reactions with Li6PS5Cl SE and reduces interface resistance. The LiCoO2 with CoO/Li2CO3 exhibits high capacity (143 mA h g(-1)), excellent cyclability (150 cycles with 89.79% capacity retention at 0.2C), and exceptional rate capability (83.4% capacity retention after 300 cycles at 0.5C in the voltage range of 2.6-4.3 V) in ASSLBs. Furthermore, at a high voltage of 4.6 V and a rate of 0.5C, the specific capacity reaches 168.6 mA h g(-1), and it still maintains a capacity of 139.9 mA h g(-1) after 150 cycles. This study highlights the significant impact of the surface chemistry of the oxide cathode on interfacial compatibility and proposes a surface reconstruction strategy based on the GSIRR process for the design of ASSLBs.