LaCl3-based sodium halide solid electrolytes with high ionic conductivity for all-solid-state batteries
Chengyu Fu, Yifan Li, Wenjie Xu, Xuyong Feng, Weijian Gu, Jue Liu, Wenwen Deng, Wei Wang, Milinda Abeykoon, Laisuo Su, Lingyun Zhu, Xiaojun Wu, Hongfa Xiang
Abstract
Abstract To enable high performance of all solid-state batteries, a catholyte should demonstrate high ionic conductivity, good compressibility and oxidative stability. Here, a LaCl 3 -based Na + superionic conductor (Na 1 − x Zr x La 1 − x Cl 4 ) with high ionic conductivity of 2.9 × 10 −4 S cm −1 (30 °C), good compressibility and high oxidative potential (3.80 V vs . Na 2 Sn) is prepared via solid state reaction combining mechanochemical method. X-ray diffraction reveals a hexagonal structure ( P6 3 /m ) of Na 1 − x Zr x La 1 − x Cl 4 , with Na + ions forming a one-dimensional diffusion channel along the c- axis. First-principle calculations combining with X-ray absorption fine structure characterization etc. reveal that the ionic conductivity of Na 1 − x Zr x La 1 − x Cl 4 is mainly determined by the size of Na + -channels and the Na + /La 3+ mixing in the one-dimensional diffusion channels. When applied as a catholyte, the NaCrO 2 ||Na 0.7 Zr 0.3 La 0.7 Cl 4 ||Na 3 PS 4 ||Na 2 Sn all-solid-state batteries demonstrate an initial capacity of 114 mA h g −1 and 88% retention after 70 cycles at 0.3 C. In addition, a high capacity of 94 mA h g −1 can be maintained at 1 C current density.