TiO2‐Induced Conversion Reaction Eliminating Li2CO3 and Pores/Voids Inside Garnet Electrolyte for Lithium–Metal Batteries.

Garnet Li7La3Zr2O12 (LLZO) is regarded as a promising solid electrolyte due to its high Li+ conductivity and excellent chemical stability, but suffers from grain boundary resistance and porous structure which restrict its practical applications in lithium–metal batteries. Herein, a novel and highly efficient TiO2‐induced conversion strategy is proposed to generate Li ion‐conductive Li0.5La0.5TiO3, which can simultaneously eliminate the pre‐existing pores/voids and contamination Li2CO3. The Li/LLZTO‐5TiO2/Li symmetric cell exhibits a high critical current density of 1.1 mA cm−2 at 25°C, and the long‐term lithium cycling stability of over 1500 h at 0.1 mA cm−2. More importantly, the excellent performance of LLZTO‐5TiO2 electrolyte is verified by LiCoO2/LiFePO4 coupled full cells. For example, The LiCoO2 coupled full cell exhibits a significant discharge rate capacity of 108 mAh g−1 at 0.1 C, and a discharge capacity retention rate of 91.23% even after 150 cycles of charge and discharge. COMSOL Multiphysics and density functional theory calculation reveal that LLZTO‐5TiO2 electrolyte has a strong lithium affinity and uniform Li ions distribution, which can improve the cycle stability of Li–metal batteries by preventing dendrite growth. [ABSTRACT FROM AUTHOR]