Electronic conductivity of solid electrolytes causes physical self-discharge in all-solid-state batteries

All-solid-state batteries (ASSBs) with inorganic solid-state electrolytes (SSEs) hold vast potential for next-generation electric vehicles (EVs) due to their high energy density and enhanced safety. However, their self-discharge behaviour, a critical factor for EVs, has not been adequately investigated so far. Here we reveal that the electronic conductivity of SSEs, typically in the range of 10⁻⁸–10⁻⁹S cm⁻¹, contributes to considerable physical self-discharge in ASSBs, particularly when the SSE thickness is on the order of tens of micrometres. To mitigate this physical self-discharge, the electronic conductivity of SSEs needs to be reduced to approximately 10⁻¹²S cm⁻¹. However, none of the prevalent SSEs meets this threshold. Therefore, reducing physical self-discharge in ASSBs will require the development of SSEs with lower electronic conductivity, alongside rational interface and full-cell designs in future research. This study provides critical insights into the self-discharge phenomenon of ASSBs, which may reshape their future design and development.