Preparation method for perfluoro-sulfonate ion exchange membrane

Abstract

The invention relates to the field of preparation of ion exchange membranes, in particular to a preparation method for a perfluoro-sulfonate ion exchange membrane for an all-vanadium redox flow battery. A perfluoro-sulfonate resin powder is obtained through dissolving perfluoro-sulfonate resin in a solvent with low toxicity and low melting point and drying the solvent; the powder can be directly stirred and dissolved in a solvent with high boiling point to prepare a membrane preparing solution with high solid content and high viscosity. According to the invention, through the adoption of a treating method for the perfluoro-sulfonate resin, the dissolving degree of the perfluoro-sulfonate resin in the solvents with high boiling point, such as dimethyl formamide, can be greatly increased, the use amount of polar solvents such as dimethyl formamide is reduced, the viscosity and solid content of the membrane preparing solution are greatly increased, and the ion exchange membrane prepared by using the membrane preparing solution has the advantages of uniform thickness, easiness in large-scale and large-size production and the like.

Description

technical field [0001] The invention relates to the field of ion-exchange membrane preparation, in particular to a method for preparing a perfluorosulfonic acid ion-exchange membrane for an all-vanadium redox flow battery. Background technique [0002] In the 1960s, DuPont of the United States developed Nafion, a commercialized perfluorosulfonic acid ion exchange membrane. This structure makes it have excellent chemical stability and thermal stability, and has good ion selectivity. Since the 1980s, this membrane has been widely used in the chlor-alkali industry and proton exchange membrane fuel cells, which has greatly promoted the development of the chlor-alkali industry and the energy industry. [0003] There are two main methods for the preparation of perfluorosulfonic acid ion exchange membranes: melt extrusion and casting. The melt extrusion method is to directly extrude perfluorosulfonic acid resin (Nafion-H) from an extruder at a certain temperature, and the extrusi...

AI Technical Summary

Problems solved by technology

This method can be used for large-scale and continuous production, with high production efficiency and large film size. However, this method has complicated production technology and high equipment investment costs. Currently, it is only mastered by a few companies such as DuPont in the United States and Asahi Kasei in Japan. , the domestic film prepared by melt extrusion often has defects such as "needle holes", which seriously affects the quality and yield of the film, so it is mostly formed by casting method; the casting method is to dissolve perfluorosulfonic acid resin in appropriate The film-forming solution (mass fraction: 5%~10%) is prepared in a solvent, and the film-forming solution is cast on a flat solid surface, and heated to evaporate the solvent to form a film. This method has simple equipment and is easy to perform, but it requires a large amount of Organic solvents, and the process of solvent volatilization leads to low production efficiency, difficult to uniform film thickness, and cannot prepare larger films, so it is mostly used in small-area, small-batch laboratory research