Local Li⁺ Framework Regulation of a Garnet-Type Solid-State Electrolyte

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.