Interface design strategy in combined materials of lithium thiophosphate electrolyte for solid-state lithium-ion batteries applications

Abstract

BackgroundSulfide-based materials are promising solid electrolytes for Li-based metal-ion batteries, owing to the high ionic conductivity, low-cost and non-toxic. MethodsIn this study, we fabricate and optimize a Li7P3S11 solid electrolyte for all-solid-state rechargeable batteries through both new approaches in material processing and cell design. The sulfide itself is prepared by a ball-mill-vacuum sealing process to yield superior electrolytes. Significant findingsA systematic investigation of the synthetic parameters, including milling time, sintering temperature, and sintering time, lead to optimal synthesis conditions of ball-milling for 20 h and vacuum sintering at 250 °C for 4 h. The resulting material exhibits a high ionic conductivity of 1.14 × 10−3 S/cm at room temperature and consists of 50% P2S74−, a notably higher amount of the polyanion than samples prepared under alternative conditions. Two types of solid-state storage systems (SSSS) were designed comparing symmetric cells containing Li-metal electrodes with equivalent cells of composite electrodes Li/Li7P3S11 (LiLPS). The relative Li-stripping/plating behavior and cycle capability over 200 cycles were tested. Whereas the symmetric Li-electrodes exhibit an interfacial resistance of 650 Ω, this value decreases remarkably to 430 Ω in the LiLPS composite electrode cell. These findings demonstrate a highly effective strategy to enhance the electrochemical stability and performance of sulfide solid electrolytes towards their suitability for all-solid-state batteries. Such a strategy could be successfully extended to other all-solid-state cell architectures.