Engineering robust interfaces for enhanced Li metal and ceramic electrolyte compatibility in solid-state systems

Abstract

Oxide ceramic electrolytes shed light on the field of solid-state electrolytes. Here, we propose a Li₂O-B₂O₃-Al₂O₃ (LBA) oxide ceramic electrolyte, which has low sintering temperature of 520 °C. Moreover, we introduce aluminum nitrate (AlN) as a sintering aid to optimize the grain boundary structure and chemistry through the liquid-phase sintering method. Currently, the main technical challenge with the oxide ceramic electrolytes is the high interfacial resistance at the electrolyte/electrode interface. Hence, we show that a polymer/ceramic/polymer sandwich-type electrolyte (PCPSE) to solve the interfacial issue of ceramic electrolytes. Notably, PCPSE alleviates the electric double layer at the electrolyte/electrode interface by blocking anionic transfer, due to extremely high Li⁺ transfer number of ceramic electrolytes. The polymer outer layer enhances physical contact with electrode and uniform Li⁺ diffusion at the interface. This sandwich architecture integrates the benefits of both polymer and ceramic electrolytes. Taken together, all-solid state Li/PCPSE/LiFePO₄ batteries demonstrates stable long-term cycling performance with a high Coulombic efficiency of 99.8 % over 100 cycles.