Interfacial Modification of Ga-Substituted Li 7 La 3 Zr 2 O 12 against Li Metal via a Simple Doping Method

Garnet Li La Zr O (LLZO) is considered a promising solid electrolyte for all-solid-state lithium-ion batteries due to its outstanding performance in which Ga-doped LLZO particularly exhibits excellent ionic conductivity. However, the application of Ga-doped LLZO is limited by the interfacial instability between Ga-doped LLZO and Li metal. In this study, Ga - and Sb -codoped LLZO is prepared using a conventional solid-state reaction method, and the effects of dual-doping on the crystal structure, microstructure, conductivity of LLZO, and battery cycle stability are investigated. The results demonstrate that the introduction of an appropriate amount of Sb into Ga -stabilized cubic-phase LLZO promotes grain contact and enhances the total ionic conductivity. The optimized Li Ga La Zr Sb O solid electrolyte exhibits the highest total ionic conductivity of 4.65 × 10 S cm at room temperature. Additionally, the introduction of Sb suppresses the formation of the LiGaO impurity phase, thereby improving the interface stability between Ga-doped LLZO and the Li metal. The assembled Li||Ga,Sb -LLZO||Li symmetric cell demonstrates stable cycling for 500 h at room temperature under a current density of 0.13 mA cm . The Li||Ga,Sb -LLZO||LiFePO full cell delivers a reversible capacity of about 140 mA h g , exhibiting negligible decay after 50 cycles. These findings suggest that the application of Ga-doped LLZO in all-solid-state lithium-ion batteries holds great promise by simply doping Zr sites with high-valence ions.