The effect of volume change and stack pressure on solid-state battery cathodes

Solid-state lithium batteries may provide increased energy density and improved safety compared with Li-ion technology. However, in a solid-state composite cathode, mechanical degradation due to repeated cathode volume changes during cycling may occur, which may be partially mitigated by applying a significant, but often impractical, uniaxial stack pressure. Herein, we compare the behavior of composite electrodes based on Li₄Ti₅O₁₂ (LTO) (negligible volume change) and Nb₂O₅ (+4% expansion) cycled at different stack pressures. The initial LTO capacity and retention are not affected by pressure but for Nb₂O₅, they are significantly lower when a stack pressure of