Sulfolane Plasticized PVDF-HFP/PEO High-Voltage Gel Polymer Electrolyte

The poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is expected to prepare electrolytes with wide electrochemical window owing to its excellent antioxidant capability. However, the inert lithium ion conduction of the C–C skeleton severely limits its electrochemical application. In this work, high-voltage-resistant sulfolane (SL) is used as a plasticizer into the PVDF-HFP skeleton to prepare gel electrolytes. Moreover, to alleviate the incompatibility of SL with lithium metal by the strong dipole–dipole interaction between poly(ethylene oxide) (PEO) and SL, a plasticized PVDF-HFP/PEO gel polymer electrolyte (PPS-GPE) was achieved, which exhibits a high ionic conductivity of 1.67 × 10–4 S cm–1 and an electrochemical stability window of 4.8 V. The assembled Li||LiCoO2 cells show a high average discharge capacity of 153 mA h g–1 between 3.0 and 4.4 V, with a retention of 77% within 400 cycles at 0.2 C. This work provides a new strategy for the development of high-voltage, high energy density, and high safety lithium metal batteries.