Stable Cycling of All-Solid-State Lithium Metal Batteries Enabled by Salt Engineering of PEO-Based Polymer Electrolytes

Poly(ethylene oxide)(PEO)-based polymer electrolytes show the prospect in all-solid-state lithium metal batteries;however,they present limitations of low room-temperature ionic conductivity,and interfacial incompatibility with high voltage cathodes.Therefore,a salt engineering of 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide lithium salt(LiHFDF)/LiTFSI system was developed in PEO-based electrolyte,demonstrating to effectively regulate Li ion transport and improve the interfacial stability under high voltage.We show,by manipulating the interaction between PEO matrix and TFSI--HFDF-,the optimized solid-state polymer electrolyte achieves maximum Li+conduction of 1.24 × 10-4 S cm-1 at 40 ℃,which is almost 3 times of the baseline.Also,the optimized polymer electrolyte demonstrates outstanding stable cycling in the LiFePO4/Li and LiNi0.8Mn0.1Co0.1O2/Li(3.0-4.4 V,200 cycles)based all-solid-state lithium batteries at 40 ℃.