Abstract: Vanadium redox flow battery （VRFB） is regarded as one of the most promising technology for efficient renewable energy storage due to its fast response, long cycle life, and high operational safety. Expanded graphite （EG）, owing to its excellent electrical conductivity and processability, is widely employed as a typical bipolar plate material in VRFB. However, pristine EG bipolar plate is prone to swelling in strongly acidic vanadium electrolyte, resulting in degraded mechanical stability and reduced conductivity, which ultimately lead to rapid efficiency loss during cycling. To address this issue, a “nanoglue” strategy using polyvinylidene fluoride （PVDF） as a structural sealant is proposed. Through high-temperature thermal treatment, PVDF uniformly infiltrates and coats the surface and cracks of EG, forming an EG/PVDF composite bipolar plate with enhanced structural integrity and electrolyte-blocking capability. This approach not only significantly improves the anti-swelling and corrosion resistance of the bipolar plate but also maintains a low resistivity. The assembled VRFB exhibits excellent cycling stability and high energy efficiency, confirming the great potential of the composite bipolar plate for high-performance redox flow battery system.