CN102024928A - Nafion ion exchange membrane used for enhanced vanadium redox battery and preparation method thereof - Google Patents

Abstract

The invention relates to the field of ion-exchange membranes for all-vanadium redox flow batteries (VRB), in particular to a perfluorosulfonic acid ion-exchange membrane for enhanced vanadium batteries and a preparation method thereof. The perfluorosulfonic acid ion exchange resin containing sulfonic acid groups is the film-forming resin, the resin is dissolved in an organic solvent to obtain a film-forming solution, and the perfluorosulfonic acid ion-exchange membrane is formed from the film-forming solution; in the perfluorosulfonic acid ion exchange There is a layer of polytetrafluoroethylene mesh in the middle of the membrane as a reinforcement material; or, there is a layer of perfluorosulfonic acid ion exchange membrane between two layers of polytetrafluoroethylene mesh. The membrane not only has high chemical stability and high current density, but also has higher mechanical strength, higher exchange capacity and lower cost than perfluorosulfonic acid membranes, and can solve the problem of perfluorosulfonic acid ion exchange membranes in the prior art. The problems of high exchange capacity and low mechanical strength, and high mechanical strength and low exchange capacity are mainly used in all-vanadium redox flow batteries (VRB).

Description

A perfluorosulfonic acid ion exchange membrane for enhanced vanadium battery and preparation method thereof

technical field

The invention relates to the field of ion-exchange membranes for all-vanadium redox flow batteries (VRB), in particular to a perfluorosulfonic acid ion-exchange membrane for enhanced vanadium batteries and a preparation method thereof.

Background technique

With the rapid development of the national economy, the contradiction between energy, resources and environmental protection has become increasingly prominent, prompting the urgent transformation of the traditional energy system to renewable energy.

Adjusting the current power energy structure and developing large-scale utilization of renewable clean energy such as wind energy and solar energy have become the basic national policies for the development of electric energy in my country. The power generation process of renewable energy such as wind energy and solar energy is discontinuous and unstable. It needs to be equipped with power storage devices to achieve continuous and stable power output, so as to avoid large-scale vicious accidents caused by impacts on local power grids. So far, among the new battery technologies developed worldwide, the all-vanadium redox flow battery (Redox flow cell) is undoubtedly the most promising. This battery has the advantages of large scale of use, long life, high energy efficiency, Environmentally friendly, good current continuity and other advantages, through the energy storage of all-vanadium redox flow battery, it can realize the function of "shaving peaks and filling valleys" in the existing power grid system, which can alleviate the contradiction between power supply and demand, and improve the utilization rate of power generation equipment. Reduce thermal power consumption.

The all-vanadium redox flow battery uses the H ₂ SO ₄ solution of V(II)/V(III) and V(IV)/V(V) redox couples as the positive and negative half-cell electrolytes, respectively. H ₂ SO ₄ is ionized into H ⁺ and SO ₄ ^2- , and then H ⁺ in the electrolyte continuously replaces H ⁺ in the ion exchange membrane, and enters the electrolyte in another chamber to complete the conduction process. When discharging, the VO ₂₊ ions in the positive electrolyte of the battery are reduced to VO ²⁺ ions, ^and the V ²⁺ ions in the negative electrolyte are oxidized to V ³⁺ ions. When charging, the process is just the opposite.

The electrode reaction of vanadium battery is as follows:

positive electrode: E ⁰ =1.00V

E⁰＝-0.26Vnegative electrode:

E ⁰ ＝-0.26V

The development of vanadium batteries has reached a relatively advanced level today, but there are still many key issues that need to be solved urgently, among which the key material diaphragm is one of them. The diaphragm in vanadium batteries has the ability to isolate positive and negative electrolyte solutions, prevent different The interaction of vanadium ions prevents cross-contamination of positive and negative electrolytes and improves ion selectivity. Protons can pass through freely and have high selectivity to vanadium in different valence states. A large number of tests have proved that the perfluorosulfonic acid ion exchange membrane has high chemical stability, high current density, and low ion conduction resistance. Among them, the Nafion117 diaphragm produced by Dubang Company has the best performance in various aspects among many diaphragms, but the cost of this diaphragm is relatively expensive; although the domestic diaphragm is low in cost, its performance is not as good as that of Nafion117 membrane. At present, perfluorosulfonic acid ion exchange membranes have the problems of high exchange capacity and low mechanical strength, and high mechanical strength and low exchange capacity. Moreover, when using wind energy and solar energy to assemble large-scale batteries in practical applications, the requirements for the mechanical strength and service life of the separator are quite high, and it is questioned whether the existing perfluorosulfonic acid ion exchange membrane can meet the requirements.

Invention content:

The purpose of the present invention is to provide a perfluorosulfonic acid ion-exchange membrane for enhanced vanadium batteries and a preparation method thereof, to solve the problem that the perfluorosulfonic acid ion-exchange membranes existing in the prior art have high exchange capacity and low mechanical strength and mechanical The problem of high strength and low exchange capacity. The enhanced perfluorosulfonic acid ion-exchange membrane is used as a diaphragm for all-vanadium redox flow batteries (VRB). Compared with the current perfluorosulfonic acid ion-exchange membrane, it has high chemical stability and high current density. , while meeting high mechanical strength, high exchange capacity, and cost reduction.

Technical scheme of the present invention is:

An enhanced perfluorosulfonic acid ion exchange membrane for vanadium batteries, the perfluorosulfonic acid ion exchange resin containing sulfonic acid groups is used as a film-forming resin, the resin is dissolved in an organic solvent to obtain a film-forming solution, and the film-forming solution is formed Perfluorosulfonic acid ion exchange membrane; there is a layer of polytetrafluoroethylene (PTFE) mesh as a reinforcement material in the middle of the perfluorosulfonic acid ion exchange membrane; or, there is a layer of full polytetrafluoroethylene (PTFE) mesh between two layers of polytetrafluoroethylene (PTFE) mesh Fluorosulfonic acid ion exchange membrane.

The film-forming solution of the perfluorosulfonic acid ion exchange resin is firmly combined with the reinforcing net through smearing and heating.

The polytetrafluoroethylene (PTFE) mesh cloth adopts glass fiber as the base material to be woven into a net-like base cloth, and then coated with polytetrafluoroethylene resin; the mesh of the mesh cloth is 0.3×0.3mm-10×10mm, and the thickness is 0.01mm-1.2mm. in,

PTFE is a polymer of tetrafluoroethylene. The basic structure is:

-CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2-.

The structure of perfluorosulfonic acid ion exchange resin is:

Wherein, X≥1, Y≥0, Z=0-3, n≥1, and the exchange capacity of the perfluorosulfonic acid ion exchange resin is IEC=0.67-1.3mmol/g.

The preparation method of the above-mentioned enhanced vanadium battery perfluorosulfonic acid ion exchange membrane, the specific steps are as follows:

(1) Dissolve the perfluorosulfonic acid ion exchange resin (exchange capacity IEC=0.67-1.3mmol/g) in the organic solvent according to the mass ratio w=5%-30%, and heat the reaction kettle to 110°C-250°C for 1 Dissolve the resin in -4h to obtain a uniform and clear film-forming solution.

Wherein, the organic solvent is xylene, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide or N-ylpyrrolidone.

(2) Vibrate the prepared film-forming solution in an ultrasonic oscillator for 30min-60min to refine the solution and drive out tiny bubbles therein.

(3) Take a certain amount of film-forming solution and cast it on a clean mold, heat it to 100°C-120°C, keep the temperature constant for 1-2h, and then place the polytetrafluoroethylene (PTFE) mesh flatly on the film-forming solution, Finally, apply the remaining film-forming solution on polytetrafluoroethylene (PTFE) mesh cloth, evaporate the solvent by heating at 120°C-180°C and constant temperature for 1-4h, and cool to room temperature. The obtained film is washed with distilled water, 50-70 ℃ drying to obtain the enhanced perfluorosulfonic acid ion exchange membrane for vanadium batteries.

Alternatively, apply the film-forming solution on a layer of polytetrafluoroethylene mesh cloth, and then cover a layer of polytetrafluoroethylene mesh cloth on the film-forming solution, and evaporate the solvent by heating at 120°C-180°C and constant temperature for 1-4h, Cool to room temperature, wash the obtained membrane with distilled water, and dry at 50-70° C. to obtain a perfluorosulfonic acid ion exchange membrane for enhanced vanadium batteries.

The mold material is glass plate, aluminum plate, stainless steel plate, polytetrafluoroethylene plate or polyvinyl chloride material.

Among the present invention, the film-forming solution 20ml that mass fraction is 10% prepares the film that thickness is 70 μm, area is ^165mm , adds the thickness of polytetrafluoroethylene (PTFE) net cloth to be the thickness of perfluorosulfonic acid ion-exchange membrane Total thickness.

Advantages of the present invention:

1. The present invention uses polytetrafluoroethylene (PTFE) mesh cloth as the reinforcing material of perfluorosulfonic acid ion exchange membrane, can significantly improve the mechanical strength of perfluorosulfonic acid ion exchange membrane, thereby guarantees to utilize wind energy, solar energy scale in practical application When assembling a large-area all-vanadium redox flow battery, the mechanical strength and service life are quite high, so as to avoid the phenomenon of rupture of the diaphragm caused by insufficient mechanical strength of the diaphragm during the process of assembling the battery or after a period of operation, and damage the operation of the entire battery. Thereby, the maintenance work on the battery is increased, that is, the cost of the battery is increased.

2. At present, perfluorosulfonic acid ion exchange membranes have the problem of high mechanical strength but low exchange capacity. Therefore, the present invention can use the high perfluorosulfonic acid ion exchange resin of exchange capacity to prepare film-forming solution because of using polytetrafluoroethylene (PTFE) mesh cloth as the reinforcing material of perfluorosulfonic acid ion exchange membrane, so that the diaphragm has high Excellent mechanical strength and high exchange capacity at the same time, improving the performance of all-vanadium redox flow battery.

3. the present invention uses polytetrafluoroethylene (PTFE) mesh cloth as the reinforcing material of perfluorosulfonic acid ion exchange membrane, under the situation of satisfying diaphragm electrochemical performance, reduces the consumption of perfluorosulfonic acid ion exchange resin, prepares diaphragm like this The cost is greatly reduced.

Description of drawings

Fig. 1 is a schematic structural view of the perfluorosulfonic acid ion exchange membrane used in the enhanced vanadium battery of the present invention.

Fig. 2 is another schematic structural view of the perfluorosulfonic acid ion exchange membrane used in the enhanced vanadium battery of the present invention.

In the figure, 1 film; 2 polytetrafluoroethylene (PTFE) mesh cloth.

Detailed ways

The technical solution of the present invention will be further specifically described below through specific implementation methods and in conjunction with the accompanying drawings.

Example 1

Dissolve 1.89g of perfluorosulfonic acid ion exchange resin (exchange capacity IEC=0.7mmol/g) in 20ml of N,N ₂ -dimethylformamide (DMF), heat the reaction kettle to 140°C for 3h to dissolve the resin, A uniform and clear film-forming solution is obtained as a film-forming solution.

First, the prepared film-forming solution was vibrated in an ultrasonic oscillator for 1 hour to refine the solution and drive away tiny air bubbles therein. Then, take 10ml of the film-forming solution and cast it on a clean mold, heat it to 100° C., keep the temperature for 1 hour, and place the polytetrafluoroethylene (PTFE) mesh cloth 2 flatly on the film-forming solution. Finally, apply the remaining 10ml film-forming solution on the polytetrafluoroethylene (PTFE) mesh cloth 2, heat to 140°C, keep the temperature for 2h, and naturally cool to room temperature. A layer of film 1 was formed on each surface, and the obtained film was washed with distilled water and dried at 60° C. to obtain a perfluorosulfonic acid ion exchange membrane for enhanced vanadium batteries ( FIG. 1 ).

In addition, it is also possible to take 20ml of the film-forming solution and smear it on a layer of polytetrafluoroethylene (PTFE) mesh cloth 2, and then cover a layer of polytetrafluoroethylene (PTFE) mesh cloth 2 on the film-forming solution, and heat it to 140°C , kept at constant temperature for 2 hours, cooled naturally to room temperature, washed the obtained membrane with distilled water, and dried at 60°C to obtain an enhanced perfluorosulfonic acid ion exchange membrane for vanadium batteries (Figure 2).

In this embodiment, the reinforcing mesh is polytetrafluoroethylene (PTFE) mesh cloth, which is made of glass fiber as the base material woven into a mesh base cloth, and then coated with polytetrafluoroethylene resin. The grid of the mesh cloth is 0.3×0.3mm, and the thickness is 0.03mm.

Example 2

It is basically the same as Example 1, except that 0.63g of perfluorosulfonic acid ion exchange resin is dissolved in 6.67ml of N,N ₂ -dimethylformamide (DMF) as a film-forming solution.

In this embodiment, the reinforcing mesh is polytetrafluoroethylene (PTFE) mesh cloth, which is made of glass fiber as the base material woven into a mesh base cloth, and then coated with polytetrafluoroethylene resin. The grid of the mesh cloth is 0.5×0.5mm, and the thickness is 0.05mm.

Example 3

It is basically the same as Example 1, except that 2.83g of perfluorosulfonic acid ion exchange resin is dissolved in 30ml of N,N ₂ -dimethylformamide (DMF) as a film-forming solution.

In this embodiment, the reinforcing mesh is polytetrafluoroethylene (PTFE) mesh cloth, which is made of glass fiber as the base material woven into a mesh base cloth, and then coated with polytetrafluoroethylene resin. The grid of the mesh cloth is 1×1mm, and the thickness is 0.1mm.

Example 4

Basically the same as Example 1, except that 5.67g of perfluorosulfonic acid ion exchange resin was dissolved in 60ml of N,N ₂ -dimethylformamide (DMF) as a film-forming solution.

In this embodiment, the reinforcing mesh is polytetrafluoroethylene (PTFE) mesh cloth, which is made of glass fiber as the base material woven into a mesh base cloth, and then coated with polytetrafluoroethylene resin. The mesh of the mesh is 2×2mm and the thickness is 0.2mm.

Example 5

It is basically the same as Example 1, except that 1.89 g of perfluorosulfonic acid ion exchange resin is dissolved in 10 ml of N, N ₂ -dimethylformamide (DMF) as a film-forming solution.

In this embodiment, the reinforcing mesh is polytetrafluoroethylene (PTFE) mesh cloth, which is made of glass fiber as the base material woven into a mesh base cloth, and then coated with polytetrafluoroethylene resin. The grid of the mesh cloth is 0.3×0.3mm, and the thickness is 0.03mm.

Example 6

It is basically the same as Example 1, except that 1.89g of perfluorosulfonic acid ion exchange resin is dissolved in 30ml of N,N ₂ -dimethylformamide (DMF) as a film-forming solution.

In this embodiment, the reinforcing mesh is polytetrafluoroethylene (PTFE) mesh cloth, which is made of glass fiber as the base material woven into a mesh base cloth, and then coated with polytetrafluoroethylene resin. The grid of the mesh cloth is 1×1mm, and the thickness is 0.1mm.

Example 7

It is basically the same as Example 1, except that 1.89g of perfluorosulfonic acid ion exchange resin is dissolved in 50ml of N,N ₂ -dimethylformamide (DMF) as a film-forming solution.

In this embodiment, the reinforcing mesh is polytetrafluoroethylene (PTFE) mesh cloth, which is made of glass fiber as the base material woven into a mesh base cloth, and then coated with polytetrafluoroethylene resin. The mesh of the mesh is 2×2mm and the thickness is 0.2mm.

Example 8

It is basically the same as Example 1, except that the exchange capacity IEC of the perfluorosulfonic acid ion exchange resin is 0.9 mmol/g.

In this embodiment, the reinforcing mesh is polytetrafluoroethylene (PTFE) mesh cloth, which is made of glass fiber as the base material woven into a mesh base cloth, and then coated with polytetrafluoroethylene resin. The grid of the mesh cloth is 0.3×0.3mm, and the thickness is 0.03mm.

Example 9

It is basically the same as Example 1, except that the exchange capacity IEC of the perfluorosulfonic acid ion exchange resin is 1.1 mmol/g.

In this embodiment, the reinforcing mesh is polytetrafluoroethylene (PTFE) mesh cloth, which is made of glass fiber as the base material woven into a mesh base cloth, and then coated with polytetrafluoroethylene resin. The grid of the mesh cloth is 1×1mm, and the thickness is 0.1mm.

Example 10

It is basically the same as Example 1, except that the exchange capacity IEC of the perfluorosulfonic acid ion exchange resin is 1.3 mmol/g.

In this embodiment, the reinforcing mesh is polytetrafluoroethylene (PTFE) mesh cloth, which is made of glass fiber as the base material woven into a mesh base cloth, and then coated with polytetrafluoroethylene resin. The mesh of the mesh is 2×2mm and the thickness is 0.2mm.

The results show that the present invention has one deck of polytetrafluoroethylene (PTFE) mesh cloth in the middle of the perfluorosulfonic acid ion exchange membrane as a reinforcing material or a layer of perfluorosulfonic acid ion exchange membrane in the middle of two layers of polytetrafluoroethylene (PTFE) mesh cloth , can make the ion exchange membrane not only have high chemical stability, high current density, but also have high mechanical strength, high exchange capacity, and low cost, and can be applied to all-vanadium redox flow battery (VRB).

Claims (8)

1. A perfluorosulfonic acid ion-exchange membrane for enhanced vanadium batteries, characterized in that: the perfluorosulfonic acid ion-exchange resin containing sulfonic acid groups is the film-forming resin, and the resin is dissolved in an organic solvent to obtain a film-forming solution , the perfluorosulfonic acid ion exchange membrane is formed from the film-forming solution; there is a layer of polytetrafluoroethylene mesh as a reinforcing material in the middle of the perfluorosulfonic acid ion exchange membrane; or, there is a layer of full polytetrafluoroethylene mesh between two layers of polytetrafluoroethylene mesh Fluorosulfonic acid ion exchange membrane. 2. The perfluorosulfonic acid ion-exchange membrane for enhanced vanadium batteries according to claim 1, characterized in that: the film-forming solution of the perfluorosulfonic acid ion-exchange resin is firmly combined with the reinforcing mesh by smearing and heating. 3. according to claim 1, the perfluorosulfonic acid ion-exchange membrane for enhanced vanadium battery is characterized in that: the polytetrafluoroethylene mesh cloth adopts glass fiber as the base material to be woven into a net-like base cloth, and then coated with Covered with polytetrafluoroethylene resin; the mesh of the mesh is 0.3×0.3mm-10×10mm, and the thickness is 0.01mm-1.2mm. 4. according to claim 1, the perfluorosulfonic acid ion exchange membrane for the enhanced vanadium battery is characterized in that: the polytetrafluoroethylene is a polymer of tetrafluoroethylene, and the basic structure is: -CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2-. 5. according to claim 1, the perfluorosulfonic acid ion exchange membrane for the enhanced vanadium battery is characterized in that: the structure of the perfluorosulfonic acid ion exchange resin is:

Wherein, X≥1, Y≥0, Z=0-3, n≥1. 6. The perfluorosulfonic acid ion exchange membrane for enhanced vanadium battery according to claim 1, characterized in that: the exchange capacity of the perfluorosulfonic acid ion exchange resin is IEC=0.67-1.3mmol/g. 7. according to the preparation method of the enhanced vanadium battery perfluorosulfonic acid ion-exchange membrane according to claim 1, it is characterized in that, concrete steps are as follows: (1) Dissolve the perfluorosulfonic acid ion exchange resin in the organic solvent according to the mass ratio w=5%-30%, and heat the reaction kettle to 110°C-250°C for 1-4h to dissolve the resin to obtain a uniform and clear film solution; (2) Vibrate the prepared film-forming solution in an ultrasonic oscillator for 30min-60min to refine the solution and drive out tiny bubbles therein; (3) Take the film-forming solution and cast it on a clean mold, heat it to 80°C-120°C, keep the temperature constant for 1-2 hours, then place the polytetrafluoroethylene mesh on the film-forming solution flatly, and finally put the remaining film-forming solution Apply the film solution on the polytetrafluoroethylene mesh, evaporate the solvent by heating at 120°C-180°C and constant temperature for 1-4h, and cool to room temperature. The obtained film is washed with distilled water and dried at 50-70°C to obtain enhanced vanadium Perfluorosulfonic acid ion exchange membrane for batteries. 8. according to the preparation method of the enhanced vanadium battery perfluorosulfonic acid ion-exchange membrane according to claim 1, it is characterized in that, concrete steps are as follows: (1) Dissolve the perfluorosulfonic acid ion exchange resin in the organic solvent according to the mass ratio w=5%-30%, and heat the reaction kettle to 110°C-250°C for 1-4h to dissolve the resin to obtain a uniform and clear film solution; (2) Vibrate the prepared film-forming solution in an ultrasonic oscillator for 30min-60min to refine the solution and drive out tiny bubbles therein; (3) Apply the film-forming solution on a layer of polytetrafluoroethylene mesh, and then cover a layer of polytetrafluoroethylene mesh on the film-forming solution, and evaporate the solvent by heating at 120°C-180°C and constant temperature for 1-4h , cooling to room temperature, washing the obtained membrane with distilled water, and drying at 50-70° C. to obtain a perfluorosulfonic acid ion exchange membrane for an enhanced vanadium battery.

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