Local Li<sup>+</sup> Framework Regulation of a Garnet-Type Solid-State Electrolyte
Furong Sun, Yubo Yang, Shu Zhao, Yongtao Wang, Mingxue Tang, Q. Huang, Yang Ren, Heng Su, Boya Wang, Ning Zhao, Xiangxin Guo, Haijun Yu
Abstract
Garnet-type solid-state electrolytes Li7La3Zr2O12 (LLZO) for high-energy-density batteries have attracted extensive attention. However, stabilizing the high-conductive cubic phase and improving its ionic conductivity remain challenges of current research. Here, a Ca–W dual-substitution strategy has been designed, and the effect of doping on cubic phase formation and Li+ mobility has been investigated thoroughly. The results indicated that the partial substitution of Ca2+ at the La3+ site and W6+ at the Zr4+ site can effectively stabilize the cubic phase while reducing the endothermic enthalpy during the synthesis. Moreover, Ca–W dual substitution regulates the local Li+ framework by increasing Li+ occupancy at the 96h site, which can significantly lower the Li+ migration barrier and thus improve the ionic conductivity by two orders of magnitude. This work addresses the challenge of stabilizing a highly conductive cubic phase with low-energy consumption and represents a major breakthrough in understanding how to improve the ionic conductivity by regulating local structures.