The Effects of Pressure on Lithium Alloying/Dealloying

Stack pressure and mechanical confinement play important roles in influencing electro-chemo-mechanical phenomena of active materials in batteries, fuel cells, electrolyzers, and other energy conversion/storage devices. Despite progress in engineering strategies that aim to achieve stable stress/strain evolution and durable device performance, our mechanistic understanding of the coupling between mechanics and electrochemistry that govern structural evolution and electrochemical behavior of electrodes remains limited. Here, we investigate the effects of stack pressure on electrochemical lithium (de)alloying using both liquid and solid-state electrolytes. We elucidate the role of stack pressure on morphological evolution and electrochemical behavior of various alloy anodes in lithium batteries. Based on the understanding gained herein, we design an interfacial layer for alloy anodes in solid-state batteries to achieve high capacity and stable cycling at low stack pressures. These results provide insight into the phase transformation mechanism of metals and alloys under mechanical confinement, and they have implications for the development of high-energy solid-state battery systems.