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

Abstract Garnet Li 7 La 3 Zr 2 O 12 (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 TiO 2 ‐induced conversion strategy is proposed to generate Li ion‐conductive Li 0.5 La 0.5 TiO 3 , which can simultaneously eliminate the pre‐existing pores/voids and contamination Li 2 CO 3 . The Li/LLZTO‐5TiO 2 /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‐5TiO 2 electrolyte is verified by LiCoO 2 /LiFePO 4 coupled full cells. For example, The LiCoO 2 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‐5TiO 2 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.