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

Abstract

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 Li_7-3xGa_xLa₃Zr₂O₁₂ 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|[email protected]|Li symmetric cells exhibit lower interfacial specific impedance (IASR) and higher critical current density (CCD) than both Li|Ag@Ga0-LLZO|Li and Li|[email protected]|Li and was stabilized at 0.15 mA/cm² for 1300 h of stable cycling. In addition, the all-solid-state battery Li|[email protected]|LFP was cycled at 0.2C for 100 cycles with 82 % capacity retention, demonstrating its promising application in lithium batteries.