Design of a fast ion-transport interlayer on cathode-electrolyte interface for solid-state lithium metal batteries

For the safety and high-energy-density, solid-state lithium metal batteries (SSLMBs) have aroused researchers’ interest, especially utilizing high-nickel layered cathode of LiNi0.8Co0.15Al0.05O2 (NCA) that coupling with solid polymer-based electrolyte (SPE). However, the applications of SPE-based SSLMBs with NCA cathode were still trucked by the deficient physical contact between NCA cathode and solid electrolyte, which contributes to the high contact resistance at cathode-electrolyte interface and thus the non-uniform delithiation/lithiation kinetics of NCA particles. Here, we designed a fast ion-transport interlayer on NCA cathode particles by chelating effect between functional group on polymer electrolyte and metal ions in NCA (PGII-NCA), aiming to build an unobstructed channel for enhanced ion-transport kinetics on NCA surface. The SSLMBs with PGII-NCA cathode deliver high capacity of 156.4 mAh g−1 and maintain 91.3% capacity after 100 cycles at room temperature. Thus, we suggest that this design strategy of modifying the NCA surface by chelating copolymer gel layer is an effective approach to tackle the sluggish kinetics on cathode-electrolyte interface, boosting the practical application of SSLMBs.