We develop a novel film electrode fabrication technology involving phase separation and self-assemble of hydrophilic and hydrophobic polymers together with the active materials, and introducing different halide ions into membrane. With the introduction of hydrated halide clusters of Cl⁻, the water contact angle of the PESAC film is reduced from 90.6° to 62.4° and the capacitance of single electrode increases from 173.0 to 242.5 F g⁻¹. Furthermore, polymer brushes of different length with halogen ions at the end of macromolecules are grafted on the surface of film and pores. There is a balance between the wettability and the steric effect.