The promise of alloy anodes for solid-state batteries

Solid-state batteries are a next-generation technology that could feature improved safety and energy density, but reliably integrating high-capacity electrode materials to enable high energy while retaining stable long-term cycling remains a challenge. Anode materials that alloy with lithium, such as silicon, tin, and aluminum, offer high capacity that can yield high-energy battery cells. The use of alloy anodes in solid-state batteries potentially offers major mechanistic benefits compared to other anode contenders and battery systems, such as lithium metal in solid-state architectures or alloys in liquid-electrolyte batteries. This perspective discusses key advantages of alloy anode materials for solid-state batteries, including the avoidance of the short circuiting observed with lithium metal and the chemo-mechanical stabilization of the solid-electrolyte interphase. We further discuss open research questions and challenges in engineering alloy-anode-based solid-state batteries, with the goal of advancing our understanding and control of alloy anode materials within solid-state architectures toward commercial application.