Mechanistic Role of External Stack Pressure on the Thermal Stability of Solid-State Batteries

Solid-state batteries (SSBs) present a promising advancement in next-generation energy storage devices due to their high energy density, power density and non-flammability. However, advancing SSBs necessitates a deep understanding of the electro-chemo-mechanical interactions at different solid/solid interfaces. While the impact of interfacial mechanisms such as interphase formation and void growth on cell performance has been studied, their core influence on the thermal stability of SSBs remains a complex area requiring further investigation. This work examines the effect of external stack pressure on the electrochemical performance and thermal stability of Li₁₀SnP₂S₁₂ (LSPS) solid electrolyte with Li metal anode. A detailed mechanistic link has been established between applied pressure, interphase propagation, and the severity of thermal runaway at the LSPS/Li interface. Additionally, the thermal runaway mechanism of LiNi_0.6Mn_0.2Co_0.2O₂(NMC622) and LSPS cathode composite has been thoroughly evaluated. Based on these comprehensive thermo-electrochemical interactions across anode/solid-electrolyte/cathode interfaces, cell-level thermal safety maps have been developed.