Reducing Gases Triggered Cathode Surface Reconstruction for Stable Cathode-Electrolyte Interface in Practical All-Solid-State Lithium Batteries.

The interfacial compatibility between cathode materials and sulfide solid-electrolytes (SEs) is a critical limiting factor of electrochemical performance in all-solid-state lithium-ion batteries (ASSLBs). In response to this challenge, this work presents a novel approach: the development of a gas-solid interface reduction reaction (GSIRR). This GSIRR process aims to mitigate the reactivity of surface oxygen by inducing a surface reconstruction layer (SRL) through an in-situ generated metal oxide on the surface of layered oxide cathode's surface. Experimental results exhibit a substantial reduction in interfacial side reactions with sulfide SEs, leading to a notable decrease in interface resistance. A specific example involves the application of a SRL, CoO/Li 2 CO 3 , onto LiCoO 2 (LCO) cathode. This modification results in impressive outcomes, including high capacity (149.7 mAh g -1 ), remarkable cyclability (retention of 84.63% over 400 cycles at 0.2C), outstanding rate capability (86.1 mAh g -1 at 2C), and exceptional stability in high-loading cathode (28.97 and 23.45 mg cm -2 ) within ASSLBs. Furthermore, the SRL CoO/Li 2 CO 3 enhances the interfacial stability between LCO and Li 10 GeP 2 S 12 as well as Li 3 PS 4 SEs. Significantly, our experiments suggest that the GSIRR mechanism can be broadly applied, not only to LCO cathodes but also to LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathodes and other reducing gases like H 2 S and CO, indicating its practical universality. This study highlights the significant influence of the surface chemistry of the oxide cathode on interfacial compatibility, and introduces a surface reconstruction strategy based on the GSIRR process as a promising avenue for designing enhanced ASSLBs. This article is protected by copyright. All rights reserved.