Importance of Li-Metal/Sulfide Electrolyte Interphase Ionic Conductivity in Suppressing Short-Circuiting of All-Solid-State Li-Metal Batteries
Motoshi Suyama, So Yubuchi, Minako Deguchi, Atsushi Sakuda, Masahiro Tatsumisago, Akitoshi Hayashi
Abstract
The electronic and ionic conductivities of the interphase that forms between Li metal and solid electrolytes (SEs) are key parameters in determining battery cell performance. In this study, we evaluated the effect of the interphase on Li dissolution/deposition behaviors. The reduction of Li 2 S–P 2 S 5 glasses to Li 2 S and Li 3 P by Li metal occurred at the Li/SE interface. The Li dissolution/deposition performance at 100 °C was improved by increasing the Li 3 P content in the interphase, and the cell with a Li 4 P 2 S 6 glass electrolyte functioned without short-circuiting at a current density of 1.3 mA cm −2 . The ionic conductivity of the Li/SE interphase was evaluated by preparing Li–SE compounds using mechanochemical processing. The milled sample prepared from Li metal and Li 4 P 2 S 6 glass showed a one order of magnitude higher conductivity of 10 −4 S cm −1 at 100 °C than that of the Li–Li 3 PS 4 milled sample, indicating that the ionic conductivity of the interphase formed at the Li/SE interface is an important factor for improving the short-circuiting tolerance of all-solid-state Li-metal batteries.