Phosphoric-acid-doped cross-linked polybenzimidazole high-temperature proton exchange membrane and preparation method thereof

Abstract

The invention relates to a phosphoric-acid-doped cross-linked polybenzimidazole high-temperature proton exchange membrane and a preparation method thereof, and belongs to the technical field of special polymer functional membranes. The preparation method comprises the steps of dissolving polybenzimidazole and hyperbranched polymer poly(p-chloromethyl styrene) in an organic solvent according to a certain ratio; then adding a hyperbranched polymer solution into a polybenzimidazole solution; fully mixing and filtering a mixed solution, and then pouring the mixed solution on a clean glass plate toform a film; and then carrying out drying after soaking in a phosphoric acid solution at a certain temperature for a certain time. The hyperbranched polymer rich in chlorine atoms is used as a cross-linking agent, the cross-linking degree can be adjusted by adjusting the percentage of the branched polymer in an imidazole group, and a three-dimensional net structure is formed in the film forming process; and meanwhile, the residual chlorine atoms in the cross-linking reaction can be converted into functional groups beneficial to proton conduction. The phosphoric-acid-doped cross-linked polybenzimidazole high-temperature proton exchange membrane prepared by the method has excellent mechanical strength and proton conduction capability and can be used for a high-temperature proton exchange membrane fuel cell.

Description

technical field [0001] The invention belongs to the technical field of special polymer functional membranes, and in particular relates to a phosphoric acid-doped cross-linked polybenzimidazole high-temperature proton exchange membrane and a preparation method thereof. Background technique [0002] Fuel cells were initially successfully used in special fields such as aerospace. In recent years, with the rapid development of economy and technology, a series of problems such as energy depletion and environmental degradation have been brought about. As a green and environmentally friendly fuel cell technology, it has begun to receive domestic and foreign attention. Widespread attention. A fuel cell is a highly efficient device that converts chemical energy, such as hydrogen, into electricity. As a kind of fuel cell, Proton Exchange Membrane Fuel Cell (PEMFC) does not produce harmful substances in the chemical reaction process, only discharges a small amount of water, and has ma...

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Problems solved by technology

[0005] However, the existing cross-linking agents suitable for PBI generally have the following problems: (1) there are very few types of cross-linking agents suitable for PBI, and only a few PBI cross-linking systems have been found; (2) reported The cross-linking agent and cross-linking method generally have low cross-linking efficiency, so the amount of cross-linking agent that needs to be introduced is large; (3) the existing cross-linking agent has harsh cross-linking conditions, cumbersome cross-linking process and difficult cross-linking degree Control problems, not suitable for industrial membrane preparation process; (4) The most critical point is that the existing crosslinking agent cannot participate in proton conduction, and its existence will affect the phosphoric acid adsorption and proton transport of PBI membranes

[0006] Hyperbranched polymers have a unique three-dimensional space structure, low viscosity, good solubility, etc., and can introduce functional groups through a large number of end groups. They have been successfully applied to functional coatings, composite materials, sensors, and drug carriers. field, but it should be said that the application field of this kind of polymer is still limited, and many potential application fields have not been touched by anyone.

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