Cross-linked electrolyte membrane and preparation method thereof

Abstract

A cross-linked polymer electrolyte membrane is prepared by using polybenzimidazole PBI as a base material. A polymer compound contains a benzene ring and a positively-charged functional group. The benzene ring in the polymer compound and the N on polybenzimidazole are connected through a chemical bond to form a cross-linked structure. The main chains of the polymer compound containing a benzene ring and a positively-charged functional group are of a polystyrene, polyether ketone, polyether ether ketone, polysulfone, polyether sulfone, polyphenylene ether or polyphenylene structure. The main chains of polybenzimidazole PBI and the main chains of the polymer compound are connected by methylene. The positively-charged functional group and the main chains of the polymer compound are connectedby methylene. The cross-linked polymer electrolyte membrane has the advantage as follows: because the positively-charged polymer is bonded with PBI to form a macromolecular cross-linked membrane, themechanical properties of the polymer electrolyte membrane can be improved, strong electrostatic interaction can be formed between positive charges and hydrogen phosphate to increase the binding energybetween positive charges and hydrogen phosphate, and the loss of phosphoric acid from the high-temperature membrane can be reduced.

Description

technical field [0001] The invention belongs to the field of high-temperature polymer electrolyte membranes, and in particular relates to the preparation of a cross-linked high-temperature polymer electrolyte membrane with strong phosphoric acid loss resistance and good dimensional stability. Background technique [0002] Compared with traditional proton exchange membrane fuel cells, high-temperature fuel cells (working temperature at 120-200°C) have the advantages of faster electrochemical reaction rate, higher tolerance to CO poisoning, and simplified water and heat management system. High-temperature fuel cells have become one of the most active research fields in recent years. As the core material of high-temperature fuel cells, high-temperature polymer electrolyte membranes need to have high proton conductivity (high temperature and low humidity environment), good thermal stability and good mechanical properties. Phosphoric acid-doped PBI (polybenzimidazole) base film ...

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Problems solved by technology

However, since phosphoric acid and PBI are only combined by hydrogen bonds, the force is relatively weak, and at the same time, phosphoric acid still exists in the high-temperature polymer electrolyte membrane in the form of free acid, so during the operation of high-temperature fuel cells, especially In the process of starting the battery, the temperature of the battery cannot be raised to a high temperature quickly, and the water produced by the battery reaction and in the air exists in a liquid form, which makes the phosphoric acid rearrange and even lose from the membrane under the action of water, resulting in the conductivity of the membrane. Rate drops, battery ohmic polarization increases, and battery performance decays

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