<p>To advance the large-scale application of vanadium redox flow batteries (VRFBs), developing proton-exchange membranes (PEMs) that combine low cost with high performance has become a key research focus. This research designed and constructed a low permeability PEM regulated by sulfonated polyethersulfones (SPAES), successfully achieving a balance between chemical stability and conductivity. The S₁K₁ PEM prepared by blending SPAES and SPEEK (Sulfonated Poly (ether ether ketone)) in equal mass ratio exhibits outstanding comprehensive performance. Its ion selectivity (8732.74 S·min⁻¹·cm⁻³) and proton conductivity (392.1 mS·cm⁻¹) are both higher than those of N212 (20.12 S·min⁻¹·cm⁻³, 213.9 mS·cm⁻¹), with a vanadium permeability of only 0.499 × 10⁻⁸ cm⁻²·min. Moreover, the VRFB assembled with the S₁K₁ PEM maintained stable energy efficiency around 70% after 100 cycles at 80&#xa0;mA·cm⁻² and sustained an operable voltage (&gt; 0.8&#xa0;V) for 445&#xa0;h. At 350&#xa0;mA·cm⁻², the maximum power density reached 973.51 mW·cm⁻² (compared to 916.2 mW·cm⁻² for N212). This blended PEM effectively integrates the material advantages of SPAES and SPEEK, offering both high proton conductivity and excellent vanadium resistance properties. Additionally, its simple preparation process and low raw material costs demonstrate promising application prospects, with the potential to accelerate the commercialization of VRFBs.</p> Graphical abstract <p></p>