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 x 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.