Influence of atmospheric moisture on the gas evolution tolerance of halide solid electrolytes
Takeshi Usami, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama
Abstract
Abstract Much attention has been paid on research and development on solid electrolytes for all-solid-state Li batteries. Although halide solid electrolytes such as Li 3 YCl 6 and Li 3 InCl 6 are promising due to fast Li ion conductivity and oxidation-resistant against positive electrode, a better understanding of their reactivity with atmospheric H 2 O is required for commercialization. In this study, the gas evolution tolerances of Li 3 YCl 6 and Li 3 InCl 6 were investigated. Temperature-programmed desorption mass spectrometry (TPD-MS) experiments at dew points below − 60 °C and gas detector tube experiments at dew points of − 30 °C both revealed significant differences in the H 2 O and HCl evolution behavior of Li 3 YCl 6 and Li 3 InCl 6 . In TPD-MS, the onset temperature of HCl evolution for Li 3 YCl 6 (~ 100 °C) was significantly lower than that for Li 3 InCl 6 (~ 220 °C), indicating that Li 3 InCl 6 solid electrolytes have superior gas evolution tolerance. This difference may be attributable to differences in the retention of H 2 O derived from the material synthesis stage and from contact with the atmosphere during the measurements. In particular, based on first-principles calculations, the low-temperature HCl evolution observed in Li 3 YCl 6 was ascribed to the partial replacement of Cl − ions by OH − ions upon contamination with trace H 2 O. Because the heating and drying of solid electrolytes (including slurries) are inevitable processes during battery manufacturing, these findings can aid in the rational design of halide solid electrolytes for all-solid-state batteries.