AC Impedance Analysis of the Degeneration and Recovery of Argyrodite Sulfide-Based Solid Electrolytes under Dry-Room-Simulated Condition
Hikaru Sano, Yusuke Morino, Akinori YABUKI, Shimpei Sato, Naohiko Itayama, Yasuyuki MATSUMURA, Masahiro Iwasaki, Masahiro Takehara, Takeshi Abe, Yasuo ISHIGURO, T. Takahashi, Norihiko MIYASHITA, Atsushi Sakuda, Akitoshi Hayashi
Abstract
Toward the development of all-solid-state batteries with enhanced performance, this study describes the investigation of the degeneration mechanism under low-humid conditions of an argyrodite-type sulfide-based solid electrolyte. The degeneration of the electrolyte with moisture occurs even under the condition of super-low humidity in a dry room with a dew point (dp) as low as −50 °Cdp. Formation of hydrogen sulfide is detected when the electrolyte is exposed to dry air with −20 °Cdp. The results of impedance measurements suggest that the grain surface of the electrolyte is degenerated with moisture, resulting in a decrease in the lithium-ion conductivity at the grain boundary. The degenerated electrolyte surface can be partially recovered by heating at 170 °C in vacuo, although a small degeneration in bulk may occur in the heating process.