Effect of Confining Pressure on the Li/Li₇La₃Zr₂O₁₂ Interface during Li Dissolution/Deposition Cycles

We experimentally demonstrate that the confining pressure inside the cell is an essential factor for realizing stable, prolonged cycles of repeated Li dissolution/deposition reactions at the interface of Li metal and garnet-type oxide-based solid-state electrolytes. The use of electrochemical impedance analysis with the internal confining pressure controllable three-electrode electrochemical setup clarified the following three effects: (i) lowering interfacial resistance by improving the adhesion of Li metal with electrolyte, (ii) suppression of void formation during Li dissolution, and (iii) prevention of Li dendritic growth. Importantly, once a high pressure was applied, these positive effects were maintained even after releasing the applied pressure. The obtained knowledge from this study is useful for the design of solid–solid interfaces and cell fabrication processes for Li-metal-based solid-state batteries.