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

Anion doping is recently attaining a lot of research interest for 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 the diffusion mechanism in c-LLZO and offer a valuable insight for the rational design of solid electrolytes.