ZHANG Wanxing, LIU Limin, ZHOU Xiaoliang, XU Yao, GUO Weilin, ZHANG Shuo
(College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, Sichuan, China)
Abstract: High fracture strength and excellent thermal stability of ion-conducting ceramic materials are important factors for solving the thermal runaway problem currently plaguing the development of alkali-metal batteries, but the high ion-transport resistance they exhibit at room temperature limits the practical performance of all-solid-state batteries. Na-β"-Al2O3 (SBA), an ionic conductor ceramics, with a unique layered two-dimensional Na+ conduction structure, is explored. LaNbO4 ceramics with "microelastic" characteristics were synthesized as the second phase to fill and modify the grain gap of SBAs to increase their room temperature ionic conductivity. In the experiment, 0.50 wt.% LaNbO4 is optimal in terms of enhancement effect, with a room temperature ionic conductivity of 2.061 mS·cm−1. The activation energy of the doped SBA was also reduced to 0.1545 eV from 0.1714 eV for the pure phase SBA. SEM images of the ceramic cross-section showed that the appropriate content of LaNbO4 not only enhanced the sintering behavior of the SBAs, but also boosted the crystallization of the SBAs, thus leading to a reduction in the impedance. Symmetric all-solid-state sodium batteries assembled with the doped SBAs could be operated at lower voltages in constant-current charge/discharge at room temperature.
Key words: ion conductor ceramics; all-solid-state battery; Na-β"-Al2O3; LaNbO4; doping modification