K2C2O4-Modified PVDF Electrolytes for Lithium-Polymer Batteries: Synergistic LiF Interphase Formation and Mechanical Reinforcement for Dendrite Suppression

Poly(vinylidene fluoride) (PVDF)-based polymer electrolytes are promising candidates for lithium-ion batteries due to their high ionic conductivity, wide electrochemical stability window, and ease of processing. However, PVDF chain scission during cycling often leads to battery failure. This study introduces a straightforward strategy for modifying PVDF using potassium oxalate (K 2 C 2 O 4 ). The resulting composite gel polymer electrolyte (CGPEK-X) facilitates the pre-formation of LiF, which enhances lithium-ion conductivity and promotes uniform lithium deposition. Moreover, the improved mechanical integrity of the composite effectively suppresses lithium dendrite growth. When integrated into LiFePO 4 /Li cells, the optimized K 2 C 2 O 4 -doped system demonstrates stable cycling over 200 cycles at room temperature, achieving a discharge capacity of 120.3 mAh g −1 at 1°C. This work presents a novel approach to engineering PVDF-based electrolytes with balanced mechanical and electrochemical properties, offering valuable insights for the development of high-performance lithium-polymer batteries.