Effects of F and Cl Doping in Cubic Li₇La₃Zr₂O₁₂ Solid Electrolyte: A First Principles Investigation

Anion doping is recently attaining a lot of research interests for the solid-state electrolytes. In this study, we investigated the effects of F and Cl on the phase, electrochemical, and chemical stabilities, ionic conductivity, and diffusion mechanism in cubic Li₇La₃Zr₂O₁₂(c-LLZO), based on density functional theory (DFT) calculations. It is found that a homogeneous diffusion network with low local structural distortion and the high Li jump numbers are beneficial for good ionic conductivity in c-LLZO. The introduction of a certain amount of Li vacancies can enhance both the Li jump numbers and the concerted migration percentage of c-LLZO. Our findings deepen the understanding of diffusion mechanism in c-LLZO and offer a valuable insight for the rational design of solid electrolytes.