• • The hybrid membrane achieves a proton/vanadium selectivity of 1×10^6 S min cm^-3, 8.6 times higher than commercial Nafion 212 (NR212), directly addressing the crossover-induced capacity decay in VRFBs.
• • VRFB single-cell tests show energy efficiencies of 88.9% at 100 mA cm^-2 and 83.2% at 200 mA cm^-2, outperforming NR212 and demonstrating high-rate capability for practical grid-scale storage.
• • The synergistic combination of PVP and 8FSiW11 enables precise regulation of ionic domains, maintaining high proton conductivity while blocking vanadium ions, effectively breaking the traditional trade-off.
• • The membrane exhibits stable cycling performance over 100 charge–discharge cycles at 100 mA cm^-2, with discharge capacity retention and self-discharge characteristics superior to NR212, indicating enhanced durability and operational lifetime.