Boosting Thermal and Mechanical Properties: Achieving High‐Safety Separator Chemically Bonded with Nano TiN Particles for High Performance Lithium‐Ion Batteries

Abstract

AbstractCurrently, the commercial separator (Celgard2500) of lithium‐ion batteries (LIBs) suffers from poor electrolyte affinity, mechanical property and thermal stability, which seriously affect the electrochemical performances and safety of LIBs. Here, the composite separators named PVDF‐HFP/TiN for high‐safety LIBs are synthesized. The integration of PVDF‐HFP and TiN forms porous structure with a uniform and rich organic framework. TiN significantly improves the adsorption between PVDF‐HFP and electrolyte, causing a higher electrolyte absorption rate (192%). Meanwhile, XPS results further demonstrate the tight link between PVDF‐HFP and TiN due to the existence of TiF bond in PVDF‐HFP/TiN, resulting in a strong impediment for the puncture of lithium dendrites as a result of the improved mechanical strengths. And PVDF‐HFP/TiN can effectively suppress the growth of lithium dendrites by means of uniform lithium flux. In addition, the excellent heat resistance of TiN improves the thermal stability of PVDF‐HFP/TiN. As a result, the LiFePO4||Li cells assembled PVDF‐HFP/TiN‐12 exhibit excellent specific capacity, rate performance, and capacity retention rate. Even the high specific capacity of 153 mAh g−1 can be obtained at the high temperature of 80 °C. Meaningfully, a reliable modification strategy for the preparation of separators with high safety and electrochemical performance in LIBs is provided.