Preparation process for composite membrane for fuel cells

A preparation process of a composite membrane for fuel cells, comprising the steps of:

• S1:
• pretreating a base membrane by impregnating the base membrane in an alkaline solvent and then irradiating the base membrane by an ultraviolet lamp, wherein the base membrane is a tetrafluoroethylene microporous membrane with a pore diameter of 1-20 μm, a porosity of 65%-90%, and a thickness of 1-30 μm;
• S2:
• impregnating the pre-treated base membrane in a solution I, performing a first-stage cooling and a second-stage cooling after drying, wherein the solution I is a mixture comprising a perfluorosulfonic acid resin solution, a water-retaining agent, and a free radical quencher, wherein in the solution I, a concentration of the perfluorosulfonic acid resin solution is 0.1 wt. %-1 wt. %, a mass of the water-retaining agent is 2%-5% of that of the perfluorosulfonic acid resin, a mass of the free radical quencher is 2%-5% of that of the perfluorosulfonic acid resin, and a mass ratio of the water-retaining agent to the free radical quencher is 1:1;
• S3:
• impregnating the base membrane after completion of S2 in a solution II, performing the first-stage cooling and the second-stage cooling after drying, wherein the solution II is a mixture comprising the perfluorosulfonic acid resin solution, the water-retaining agent, and the free radical quencher, wherein in the solution II, a concentration of the perfluorosulfonic acid resin solution is 2 wt. %-6 wt. %, a mass of the water-retaining agent is 2%-5% of that of the perfluorosulfonic acid resin, a mass of the free radical quencher is 2%-5% of that of the perfluorosulfonic acid resin, and a mass ratio of the water-retaining agent to the free radical quencher is 1:1;
• and
• S4:
• impregnating the base membrane after completion of S3 in a solution III, performing the first-stage cooling after drying, wherein the solution III is a mixture comprising the perfluorosulfonic acid resin solution with a concentration of 7 wt. %-20 wt. % and a sulfonated polyetheretherketone solution with a concentration of 7 wt. %-20 wt. %, and a mass ratio of the perfluorosulfonic acid resin and the sulfonated polyetheretherketone is 1:1, wherein a temperature of the first-stage cooling is 40-50° C. and a temperature of the second-stage cooling is 0-10° C.