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.