Sintering temperature dependency on sodium‐ion conductivity for Na ₂ Zn ₂ TeO ₆ solid electrolyte

Abstract We investigated the sintering temperature dependency on the properties of Na ₂ Zn ₂ TeO ₆ (NZTO) solid electrolyte synthesized via a conventional solid‐state reaction method. Sintering temperature of calcined NZTO powder, which was obtained by the calcination of precursor at 850℃, was changed in the range from 650 to 850℃. X‐ray diffraction analysis showed that P2‐type layered NZTO phase was formed in all sintered samples without forming any secondary phases. The relative densities of sintered NZTO samples were approximately 83%−85% for the samples sintered at 700℃ or higher. The all sintered samples showed sodium‐ion conductivity above 10 ⁻⁴ S cm ⁻¹ at room temperature and the highest conductivity of 4.0 × 10 ⁻⁴ S cm ⁻¹ in the sample sintered at 750℃. The sintering temperature to obtain the highest room temperature conductivity is 100℃ lower than that used in previous works. Such low sintering temperature compared to other Na‐based oxide solid electrolytes could be useful for co‐sintering with electrode active materials for fabrication of all‐solid‐state sodium‐ion battery.