Preparation method for compound proton exchange membrane for high-temperature-resisting fuel cell

Abstract

The invention relates to a proton exchange membrane, particularly relates to a preparation method for a compound proton exchange membrane for a high-temperature-resisting fuel cell, and belongs to the field of fuel cells. According to the preparation method, a precursor containing an imidazole ring is put into a polybenzimidazole solution to be directly subjected to a sol-gel method to be crossly linked into a membrane and the membrane is adsorbed with phosphoric acid to be prepared into a phosphoric acid doped proton exchange membrane. Compared with the prior art, the preparation method for the compound proton exchange membrane for the high-temperature-resisting fuel cell has the following advantages that the precursor containing the imidazole ring is put into the polybenzimidazole solution to be directly subjected to the sol-gel method to be crossly linked into the membrane; the preparation method is simple and controllable; an imidazole structure contained in a silicon nano particle can react with the phosphoric acid to generate an imidazolium salt; one part of the phosphoric acid is fixed and the generated imidazolium salt has a certain adsorption effect on the free phosphoric acid, so that the adsorption capability to the phosphoric acid by a PBI (Polybenzimidazole) compound membrane is improved greatly and the leakage and loss of the phosphoric acid are inhibited; therefore, the proton conductivity of the proton exchange membrane is improved.

Description

technical field [0001] The invention relates to a proton exchange membrane, in particular to a method for preparing a composite proton exchange membrane of a high-temperature-resistant fuel cell, belonging to the field of fuel cells. technical background [0002] Proton exchange membrane (PEM) is one of the key components in proton exchange membrane fuel cells (Proton exchange membrane fuel cells, PEMFCs). As the base material of the electrolyte and electrode active substances, its properties determine the main technical characteristics and performance of the battery's construction and operation. Its properties directly determine the performance of the fuel cell; therefore, the performance and service life of the fuel cell are closely related to the proton exchange membrane. There is a great relationship between the nature of the PEM, and the PEM should meet the following requirements: [0003] (l) The proton membrane used in direct methanol fuel cells needs to have a low m...

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Problems solved by technology

[0010] (1) When operating under high temperature and low humidity conditions (higher than 80°C), the proton conductivity of the membrane will drop significantly due to the decrease of the relative humidity of the membrane;

[0011] (2) The permeability coefficient of the fuel is high, especially when methanol is used as the fuel, resulting in a large loss of fuel, and the methanol penetrates the membrane and reaches the cathode, which will reduce the open circuit voltage, greatly shortening the service life and efficiency of the fuel cell;

[0012] (3) High price;

[0013] (4) Difficult to process

[0015] Polybenzimidazole (PBI) has excellent thermal stability, chemical stability, and mechanical stability, so it has attracted extensive attention from researchers; however, PBI itself does not have the ability to conduct protons, so pure PBI cannot be used. for the preparation of proton exchange membranes

The introduction of phosphoric acid into PBI, that is, the preparation of phosphoric acid-doped PBI membrane can improve the proton conductivity of PBI (see literature: Progress in Polymer Science, 2009, 34, 449-477); however, phosphoric acid-doped PBI membrane in the process of use Phosphoric acid in the medium will seep and lose, resulting in a decrease in the performance of the proton exchange membrane, as reported in the literature (J. Mater. Chem., 2012, 22, 18411-18417), doping nanoparticles (SiO 2 etc.) can inhibit the leakage of phosphoric acid to a certain extent. However, the preparation process of monodisperse nanoparticles in this report is relatively complicated, and the ability of nanoparticles to inhibit the leakage of phosphoric acid is limited by the doping amount of nanoparticles. Nanoparticles The greater the doping amount, the better the effect of inhibiting phosphoric acid leakage, but excessive doping will lead to a decrease in the mechanical properties of the composite membrane, and the ability of the composite membrane to absorb phosphoric acid needs to be further improved

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