Low-temperature flash sintering of dense Ta-doped Li7La3Zr2O12 solid electrolyte for solid-state lithium batteries

Abstract

To achieve high density and high Li-ion conductivity in the garnet LLZO (Li₇La₃Zr₂O₁₂), an effective strategy is to dope it with high-valence elements to stabilize the cubic phase and to lower the sintering temperature. As well known, flash sintering (FS) is characterized by short sintering times and low furnace temperature. Herein, the doping modification of Ta-LLZO by flash sintering at 700 °C for the higher conductivity of LLZO was investigated in the present study. The results indicate that the addition of an appropriate amount of Ta⁵⁺ can enhance the ionic conductivity. The relative density of the sintered cubic Li_6.4La₃Zr_1.4Ta_0.6O₁₂ is 94.72%, with a corresponding total ion conductivity of 9.8 × 10^–4 S cm⁻¹, demonstrating good electrical performance. A solid-state lithium metal battery with Li_6.4La₃Zr_1.4Ta_0.6O₁₂ electrolyte was assembled, and its electrical performance was tested at 50 °C. The results showed that an initial discharge specific capacity of 126.5 mAh g⁻¹ at a 0.1C rate could be reached.