Preparation method of polybenzimidazole multi-layer composite membrane for high-temperature fuel cell

The invention discloses a preparation method of a polybenzimidazole multi-layer composite membrane for a high-temperature fuel cell; a polybenzimidazole porous inner layer is prepared by a water vapor induced phase separation method, polybenzimidazole dense layers are prepared on two sides of the polybenzimidazole porous inner layer by a spraying method, and then dipping is performed with phosphoric acid. The prepared polybenzimidazole multi-layer composite membrane has the advantages of uniform structure, close combination between layers, simple preparation process and low material costs, and is applicable to a high-temperature proton exchange membrane fuel cell with an anhydrous system and a working temperature of 120 DEG C-200 DEG C; the phosphoric acid adsorption capacity is improved, the alcohol-rejecting ability of the composite membrane is effectively improved, the composite membrane has relatively high electric conductivity, and the loss of phosphoric acid is greatly reduced.