The influence of pressure on lithium dealloying in solid-state and liquid electrolyte batteries

Dealloying reactions underpin the operation of next-generation battery electrodes and are also a synthesis route for porous metals, but the influence of mechanical stress on these processes is not well understood. Here we investigate how the applied stack pressure affects structural evolution and electrochemical reversibility during the alloying/dealloying of Li alloy materials (Li-Al, Li-Sn, Li-In and Li-Si) using solid-state and liquid electrolytes. The extent of porosity formation during the dealloying of metals is found to be universally governed by stack pressure, with pressures of at least 20% of the yield strength required to achieve similar to 80% relative density. This concept is correlated to the cycling of alloy electrodes in solid-state batteries, with a yield-strength-dependent threshold pressure needed for reversible high Li-storage capacity due to densification. With this understanding, we design Al and Si anodes with a densified interfacial layer enabling stable cycling at low stack pressures (2 MPa), providing guidance towards practical high-energy solid-state batteries.