Elucidating Electrodeposition Instability at the Solid-solid Interface

Metallic anodes could potentially alter the future of energy storage; however, their irregular electrodeposition has been a long-standing concern. It is often argued that the solid electrolytes should lead to uniform deposition since additional strain energy has to be spent in growing an irregular deposit. In other words, the mechanical rigidity of the solid electrolytes should foster stable deposition. Despite this intuitive argument, often irregular deposition takes place at higher currents, even if the electrolyte has enough mechanical stiffness. Here we investigate the electrodeposition dynamics at a solid-solid interface. We find that the stress-field alters the conduction pathways in the electrolyte and gives rise to a non-monotonic ionic transport. Additionally, the strain-energy alters the reaction free-energy landscape and causes further complexations. The electrodeposition at the solid-solid interface turns out to be governed by both the bulk as well as surface characteristics.