Advanced semi-interpenetrating polymer network gel electrolyte for rechargeable lithium batteries

A new type of semi-interpenetrating polymer network (Semi-IPN) gel polymer electrolyte (GPE) membrane based on the cross-linked poly(ethylene glycol) diacrylate-co-poly(vinylene carbonate) P(EGDA-co-VC) and PVDF-HFP linear polymer is successfully synthesized by UV-cured technology. The cross-linked P(EGDA-co-VC) can accommodate a large amount of liquid electrolyte inside the non-porous membrane via its strong interaction with Li+ and solvents, which avoids the liquid electrolyte leakage. The ionic conductivity of the Semi-IPN GPE reaches 1.49 × 10−3 S cm−1 at 25 °C and the electrochemical stability window up to 4.2 V (versus Li/Li+). It demonstrates excellent interface stability to lithium metal electrode, superior thermal stability and good mechanical properties. A symmetric Li/Li cell with the above electrolyte displays a lower voltage polarization and longer valid cycle life than that based on conventional liquid electrolyte. Moreover, the Li/LiFePO4 cells using the Semi-IPN GPE show superior cycling stability and rate performance comparable to the cell based on conventional liquid electrolyte. This Semi-IPN GPE is promising for rechargeable lithium batteries with high safety and energy density.