Electrodeposition and Mechanical Stability at Lithium-Solid Electrolyte Interface during Plating in Solid-State Batteries

Interfacial deposition stability between lithium metal and a solid electrolyte (SE) is important in preventing interfacial contact loss, mechanical fracture, and dendrite growth in Li-metal solid-state batteries (SSBs). In this work, we investigate the deposition and mechanical stability at the Li-metal/SE interface and its consequences (such as SE fracture and contact loss). A wide range of contributing factors are investigated, such as charge and mass transfer kinetics, plasticity of Li-metal and fracture of the SE, and the applied stack pressure. We quantify the effect of the ionic conductivity of the SE, the exchange current density of the interfacial charge-transfer reaction, and SE surface roughness on the Li deposition stability at the Li-metal/SE interface. We also propose a “mechanical stability window” for the applied stack pressure that can prevent both contact loss and SE fracture, which can be extended to other metal-electrode (e.g., sodium) SSB systems.