The effect of Ga doping on the microstructure and electrochemical properties of Li7La3Zr2O12 garnet-type solid electrolyte

• Published in: Solid state ionics 2025-02, Vol.420, p.116765, Article 116765
• Main Authors: Fu, Shihao, Li, Pingmei, Yu, Shiyu, Hu, Yang, Liu, Yibo, Chen, Daming, Wei, Yaqing, Li, Yuanxun, Chen, Yong
• Format: Article
• Language: English
• Subjects: All-solid-state battery; Ionic conductivity; Li+ transport; Li7−3xGaxLa3Zr2O12 garnet
• ISSN: 0167-2738
• DOI: 10.1016/j.ssi.2024.116765

The garnet-type Li7La3Zr2O12 (LLZO) has garnered significant attention due to its superior thermal stability and broad electrochemical window. However, LLZO exhibits instability at room temperature and readily transforms from a cubic phase (c-LLZO) to a tetragonal phase (t-LLZO), resulting in issues such as low ionic conductivity. Herein, the effect of Ga doping on LLZO is investigated. Combined with SEM, activation energy, ionic conductivity and XRD refinement, the results demonstrate that Li7-3xGaxLa3Zr2O12 exhibits better properties when x = 0.25. Solid-state nuclear magnetic resonance (SSNMR) showed that Ga0.25-LLZO was favorable for promoting Li+ transport. Moreover, Li|Ag@Ga0.25-LLZO|Li symmetric cells exhibit lower interfacial specific impedance (IASR) and higher critical current density (CCD) than both Li|Ag@Ga0-LLZO|Li and Li|Ag@Al0.32-LLZO|Li and was stabilized at 0.15 mA/cm2 for 1300 h of stable cycling. In addition, the all-solid-state battery Li|Ag@Ga0.25-LLZO|LFP was cycled at 0.2C for 100 cycles with 82 % capacity retention, demonstrating its promising application in lithium batteries. [Display omitted] •The Ga-LLZO electrolyte doped with different Ga content was successfully constructed, and the optimal doping amount of Ga was proved to be 0.25, Li6.25Ga0.25La3Zr2O12 (Ga0.25-LLZO), which has a high ionic conductivity (1.56 × 10−4 S/cm), as well as a low activation energy (0.377 eV).•Solid-state nuclear magnetic (SSNMR) tests, revealing that Ga0.25-LLZO better promotes Li+ migration.•The CCD of Li|Ag@Ga0.25-LLZO|Li reaches 1.24 mA/cm2, it can be stably cycled for 1300 h at 0.15 mA/cm2.•Li|Ag@Ga0.25-LLZO|LFP has a discharge specific capacity of 158 mAh/g, and the capacity retention rate is 82 % after 100 cycles at 0.2C.