Grain Boundary Electronic Insulation for High‐Performance All‐Solid‐State Lithium Batteries

Abstract Sulfide electrolytes with high ionic conductivities are one of the most highly sought for all‐solid‐state lithium batteries (ASSLBs). However, the non‐negligible electronic conductivities of sulfide electrolytes (≈10 −8 S cm −1 ) lead to electron smooth transport through the sulfide electrolyte pellets, resulting in Li dendrite directly depositing at the grain boundaries (GBs) and serious self‐discharge. Here, a grain‐boundary electronic insulation (GBEI) strategy is proposed to block electron transport across the GBs, enabling Li−Li symmetric cells with 30 times longer cycling life and Li−LiCoO 2 full cells with three times lower self‐discharging rate than pristine sulfide electrolytes. The Li−LiCoO 2 ASSLBs deliver high capacity retention of 80 % at 650 cycles and stable cycling performance for over 2600 cycles at 0.5 mA cm −2 . The innovation of the GBEI strategy provides a new direction to pursue high‐performance ASSLBs via tailoring the electronic conductivity.