Inorganic nanoparticle in-situ modified polybenzimidazole proton exchange membrane and preparation method thereof

Abstract

The invention relates to an inorganic nanoparticle in-situ modified polybenzimidazole proton exchange membrane and a preparation method thereof. The proton exchange membrane composition comprises an in-situ polymerized polybenzimidazole polymer, stereoscopic cage-structure polysilsesquioxane nanoparticles with eight amino acids, and doped phosphoric acid. In the composition, the adsorbed phosphoric acid exists in the form of ionic chemical bonds, so that protons can be transferred through abundant phosphoric acid in the proton exchange membrane, and the conductivity can not decrease due to the loss of the phosphoric acid; and besides, the introduced siloxane has very high water absorption and water retaining capacities, thereby enhancing the properties of the proton exchange membrane and prolonging the service life.

Description

technical field [0001] The invention relates to a polymer electrolyte membrane for a proton exchange membrane fuel cell and a preparation method thereof, in particular to an inorganic nanoparticle in-situ modified polybenzimidazole proton exchange membrane and a preparation method thereof. Background technique [0002] Perfluorosulfonic acid ion exchange membranes have been widely used in the fields of proton exchange membrane fuel cells, chlor-alkali chemical industry and electrochemical analysis. The raw material used in the membrane material is perfluorosulfonic acid resin, which is currently commercialized by DuPont, Dow, Asahi Kasei, Asahi Glass, and Shandong Dongyue Group. Perfluorosulfonic acid resin itself has a low glass transition temperature, so it will soften when it is used in an environment with a temperature exceeding 100 ° C. When it is used to make membrane electrodes for proton exchange membrane fuel cells, it will cause severe deformation of the membrane e...

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Problems solved by technology

However, phosphoric acid-doped polybenzimidazole membrane materials used in high-temperature and low-humidity environments also have defects, mainly in three aspects: first, proton transfer mainly depends on the doping amount of phosphoric acid, and each polybenzimidazole molecular structure The imidazole group can only bind two phosphoric acid molecules at most. According to this ratio, each polybenzimidazole repeating unit can only chemically adsorb 4 phosphoric acid molecules, resulting in low proton conductivity; second, it is used in proton exchange membrane fuel The actual adsorption amount of phosphoric acid in the phosphoric acid-doped polybenzimidazole membrane of the battery is higher than the ratio of 4 phosphoric acid molecules adsorbed by each polybenzimidazole repeating unit, that is to say, the excess phosphoric acid exists as free phosphoric acid molecules, while the electrode in the cathode A large amount of water will be generated in the chemical reaction, so that free phosphoric acid is dissolved in water and discharged from the proton exchange membrane. After imidazole is doped with phosphoric acid, the mechanical strength of the proton exchange membrane will decrease due to the "lubricating" effect of phosphoric acid molecules, so that the proton conductivity will be significantly reduced due to softening and deformation during long-term operation in a high temperature environment

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