In situ generated Li2S-LPS composite for all-solid-state lithium-sulfur battery

Abstract

Li3PS4(LPS) was in situ formed at the active material Li2S through the reaction of Li2S and P2S5 by mechanical ball milling, which can be used to composite cathode for Li/S battery. The fine active materials-electrolyte interface will be generated via in situ reaction. Compared with the direct mixing Li2S + LPS, the interface impedance between Li2S and LPS of Li2S-LPS had a significant decrease from 833.3 Ω to 203.7 Ω at room temperature. The effect of heat treatment temperature on the ionic conductivities of Li2S-LPS has been studied, and the Li2S-LPS-300 showed the highest ionic conductivity of 2.67 × 10−4 S cm−1 at room temperature. The all-solid-state cell (Li/LPS/Li2S-LPS) possessed a larger capacity and better rate performance than that of the cell using Li2S + LPS as cathode material, showing a discharge capacity of 624.5 mAh g−1 (g of Li2S) for the 20th cycle. We also find that high carbon content of composite cathode will reduce the utilization of Li2S. The composite cathode 90Li2S-LPS + 10C (wt%) shows the highest capacity of 763.8 mAh g−1 at the current density of 0.1 mA cm−2.