Alloy Anodes in Sulfide-Based Solid-State Batteries

Alloy anodes offer high theoretical capacity, but they typically exhibit fast capacity decay in lithium-ion batteries because of excessive solid-electrolyte interphase growth. Here, we investigate a variety of alloy anodes in sulfide solid-state batteries, and we show that they can exhibit significantly improved interfacial stability and enhanced cyclability when engineered effectively. In situ measurement of stack pressure evolution during cycling shows that the volume changes of alloy anodes can lead to large pressure swings within the solid-state battery cell, giving insight into electrode composite evolution. We further investigate the fundamental electrochemical behavior of 12 different foil-based alloy anode materials in solid-state batteries, and we find that lithium trapping by the delithiated phase can play a key role in limiting performance. Based on these insights, we present a new design for dense foil aluminum-based alloy anodes with multiphase microstructure that offers significantly improved performance due to retained transport pathways within the foil. This design offers a paradigm that does away with slurry coating, potentially reducing manufacturing costs. In addition, we investigate solid-state dealloying of foil anodes to understand the interplay between densification and interfacial contact evolution at different stack pressures. Taken together, these findings show the importance of controlling chemo-mechanics and interfaces in alloy anodes for sulfide-based solid-state batteries for improved energy storage capabilities.