Importance of Li-Metal/Sulfide Electrolyte Interphase Ionic Conductivity in Suppressing Short-Circuiting of All-Solid-State Li-Metal Batteries

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 Li2S-P2S5 glasses to Li2S and Li3P by Li metal occurred at the Li/SE interface. The Li dissolution/deposition performance at 100 degrees C was improved by increasing the Li3P content in the interphase, and the cell with a Li4P2S6 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 Li4P2S6 glass showed a one order of magnitude higher conductivity of 10(-4) S cm(-1) at 100 degrees C than that of the Li-Li3PS4 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.