Reaction Kinetics of Carbonation at the Surface of Garnet-Type Li₇La₃Zr₂O₁₂ as Solid Electrolytes for All-Solid-State Li Ion Batteries

Abstract

Garnet-type Li 7 La 3 Zr 2 O 12 has attracted attention as a promising candidate for solid electrolytes in all-solid-state lithium ion metal batteries because it exhibits high Li ion conductivity and is inert in the presence of metallic Li. However, this material is known to react with water and carbon dioxide gas, even under ambient conditions, which can cause degradation, such as a decrease in ionic conductivity. In this study, the reaction rate of the carbonation processes under both humid and dry conditions was evaluated using thermal analysis. We confirmed that carbonation did not occur at <700 K under dry conditions. The reaction kinetics were found to initially be phase-boundary controlled and then diffusion controlled, and the corresponding activation energies were estimated to be 0.5 and 0.8 eV, respectively.