Ga/Ta dual substituted Li7La3Zr2O12 electrolyte for Li-ion batteries

Co-doping outperforms single-element Ta doping in boosting the ionic conductivity of LLZO through the optimization of lithium-ion and vacancy concentrations. In the present study, the synergistic effects of Ga/Ta dual substitution at the Li and Zr sites in the LLZO electrolyte are discussed with respect to its cubic phase stability and ionic conductivity. Based on our previous discussion about the optimized Ta-doped LLZO, Li 6.4-3x Ga x La 3 Zr 1.4 Ta 0.6 O 12 (x = 0, 0.05, 0.1, 0.15, 0.2) with a cubic garnet structure is synthesized by flash sintering. Our findings demonstrate that the Ga doping concentration is correlated with both the lattice parameters and Li + vacancy density of Li 6.4-3x Ga x La 3 Zr 1.4 Ta 0.6 O 12 , thereby enhancing its Li + conductivity. The Li + conduction mechanism underlying the enhanced ionic conductivity induced by Ga/Ta co-doping is proposed based on the analysis of the radial distribution function (RDF). Under the condition of room temperature, the optimized Li 5.95 Ga 0.15 La 3 Zr 1.4 Ta 0.6 O 12 solid electrolyte exhibits higher total ionic conductivity of 7.57 × 10 −4 S cm −1 . The constructed Li/LG 0.15 LZTO/Li symmetric cell shows stable cycling ability for 1300 h at 50 °C with a current density of 0.1 mA cm −2 . The initial discharge capacity of the Li/LG 0.15 LZTO/LiFePO 4 cell attains 127.3 mAh g −1 .