Pre-modified Li₃PS₄ based interphase for lithium anode towards high-performance Li-S battery

Due to the high theoretical specific capacity and energy density, lithium sulfur battery is regarded as a potential candidate for next generation energy storage devices. However, severe corrosion reaction between polysulfides and lithium anode causes the poor cycling stability and low coulombic efficiency. Herein, we demonstrate the construction of protective layer on lithium anodes by a spontaneous and rapid reaction between Li metal and the mixture solution of P₂S₅ and S in THF. The main constituents of the protective layer are confirmed as a sulfide lithium ion solid electrolyte Li₃PS₄ and its derivatives, which effectively stabilize the interphase of lithium anode and suppress the shuttle effect in the Li-S batteries, enabling the greatly enhanced cycling stability and Coulombic efficiency. With modification of lithium anode, the lithium sulfur batteries exhibit a specific capacity of 840 mA h g⁻¹ after 200 cycles at 0.3 C with average Coulombic efficiency of 90.1% without LiNO₃ additives in the electrolyte. Moreover, by applying Li₃PS₄ modified Li anode, Li-S pouch cells with sulfur loading of 3.8–4.2 mg cm⁻² deliver good cycling performance of 803 mA h g⁻¹ with average Coulombic efficiency of 90% after 20 cycles. Hence, introducing sulfide solid electrolyte as protective layer of Li anode provides a new strategy for the improvement of lithium sulfur batteries.