Grain-Boundary Electronic Insulation and Interfacial Self-Passivation Synergistic Strategy for High-Performance all-Solid-State Lithium Batteries.

Sulfide-based all-solid-state lithium batteries (ASSLBs) have attracted tremendous attention due to their high energy density and superior safety characteristics. However, the practical application of ASSLBs is severely hindered by the formation of lithium dendrites. The grain boundaries (GBs) in sulfide solid electrolytes (SSEs) serve as primary channels for electron leakage, facilitating electron transport within SSEs particles and leading to lithium dendrite deposition at GBs. Moreover, the unstable interface between SSEs and lithium metal accelerates lithium dendrite growth. Herein, a synergistic strategy of GB electronic insulation and interfacial self-passivation is proposed. Polytetrafluoroethylene (PTFE) is introduced as a modifier for the GBs in Li6PS5Cl (LPSC) via a dry ball-milling process. This approach reduces the electronic conductivity, blocks electron transport along GBs, and simultaneously generates an in situ LiF interfacial passivation layer at the interface with lithium metal, thereby suppressing lithium dendrite growth. The critical current density (CCD) is increased to 4.6 mA cm-2, and the Li||Li symmetric battery achieves stable cycling for over 2600 h. The innovative synergistic strategy of grain boundary electronic insulation and interfacial self-passivation provides a new direction for pursuing high-performance ASSLBs.