Preparation of Li7La3(Zr2 − x,Nbx)O12 (x = 0-1.5) and Li3BO3/LiBO2 composites at low temperatures using a sol-gel process

Li7La3(Zr2 − xNbx)O12 (LLZNbO, x = 0-1.5) was prepared using sol-gel process at low temperatures. Additives (LiBO2 and Li3BO3) were used to improve the sintering of the ceramic electrolyte at low temperatures. XRD patterns of the calcined powder displayed the formation of cubic garnet phase between 600 and 700 °C in composition with higher Nb content (LLZNbO, x ≥ 0.5). The density of composites with additives sintered at 900 °C achieves 90%. In composites sintered with LiBO2, the presence of La2Zr2O7 was detected, whereas single cubic phase was obtained for the composites sintered with Li3BO3. The ion conductivity attained was 7 × 10− 5 S/cm at 30 °C using 6.5 wt% Li3BO3 (900 °C), representing enhancement by more than two orders of magnitude compared to the material without additives. Improvements of Li ion conductivity can be interpreted by the enhanced relative density as the result of the rearrangement of particles produced by adequate concentration of the additive.