Silicon is a promising anode material for solid-state batteries (SSBs) due to its high theoretical capacity and low dendrite formation risk. However, its electrochemical performance is hindered by low actual capacity and fast capacity decay. This study reveals the chemo-mechanical failure mechanisms of composite Si/LiₓPSₓClₓ and solid-electrolyte-free silicon anodes using structural and chemical characterizations and theoretical simulations. Solid electrolyte interphase (SEI) growth at the Si/LiₓPSₓClₓ interface causes severe resistance increase in composite anodes, leading to rapid capacity decay. Solid-electrolyte-free anodes show high specific capacity but suffer from microscale void formation during delithiation, causing high mechanical stress at the 2D interfaces. Understanding these mechanisms provides guidelines for designing improved electrode materials.

Hanyu Huo, Ming Jiang, Yang Bai, Shamail Ahmed, Kerstin Volz, Hannah Hartmann, Anja Henss, Chandra Veer Singh, Dierk Raabe, Jürgen Janek