Stress evolution during cycling of alloy-anode solid-state batteries

Alloy anodes hold promise for enabling high-energy solid-state batteries, but their substantial volume changes during charge/discharge can cause structural and mechanical degradation within the all-solid-state environment. It is therefore critical to understand how material evolution and mechanical stress within alloy-anode-based solid-state batteries are related. Here, we investigate stress (stack pressure) evolution within batteries with composite anodes that contain active materials such as silicon, tin, and antimony, along with an argyrodite-type electrolyte and LiNi0.33Mn0.33Co0.33O2 cathodes. We measure megapascal-level stress changes that are dependent on the amount of lithium transferred, and we find that stress signatures and hysteresis during charge/discharge are affected by the electrode structure and the active material. We furthermore show that these composite-alloy anodes enable stable long-term cycling with associated cyclic-stress changes. These findings provide new understanding of the relationship between electrochemistry and mechanics within solid-state batteries, which is important because megapascal-level stack pressures are generally necessary for optimal performance.