阅读说明：本技术 磺化石墨烯改性全氟磺酸离子交换膜及其制备方法 (Sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane and preparation method thereof ) 是由 马灼明 邹业成 丁涵 张永明 于 2020-06-22 设计创作，主要内容包括：本发明涉及一种磺化石墨烯改性全氟磺酸离子交换膜及其制备方法,属于离子交换膜技术领域。本发明所述的磺化石墨烯改性全氟磺酸离子交换膜,由磺化石墨烯与全氟磺酸树脂溶液混合后采用流延法成型制得。本发明所述的磺化石墨烯改性全氟磺酸离子交换膜,既具有高质子传导率,又具有较高的机械强度；同时本发明还提供了一种设计科学合理、简单易行的制备方法。(The invention relates to a sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane and a preparation method thereof, belonging to the technical field of ion exchange membranes. The sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane is prepared by mixing sulfonated graphene and a perfluorinated sulfonic acid resin solution and then molding by adopting a tape casting method. The sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane disclosed by the invention has high proton conductivity and high mechanical strength; meanwhile, the invention also provides a preparation method which is scientific and reasonable in design, simple and easy to implement.)

1. A sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane is characterized in that: the sulfonated graphene/perfluorosulfonic acid composite material is prepared by mixing sulfonated graphene and a perfluorosulfonic acid resin solution and then molding by adopting a tape casting method.

2. The sulfonated graphene modified perfluorosulfonic acid ion exchange membrane according to claim 1, wherein: the content of the sulfonated graphene in the mixed solution is 0.1-20 wt%, the solid content of the perfluorinated sulfonic acid resin solution is 5-40 wt%, and the viscosity is 40-300 cps.

3. The sulfonated graphene modified perfluorosulfonic acid ion exchange membrane according to claim 1, wherein: the number of sulfonated graphene layers is less than 10, the radial size is 50nm-50 mu m, the thickness is 1-50nm, and the content of S element is 0.1-20 wt%.

4. The sulfonated graphene modified perfluorosulfonic acid ion exchange membrane according to claim 1, wherein: the perfluorinated sulfonic acid resin is one or two of long-chain branched perfluorinated sulfonic acid resin or short-chain branched perfluorinated sulfonic acid resin.

5. The sulfonated graphene modified perfluorosulfonic acid ion exchange membrane according to claim 1, wherein: the EW value of the perfluorosulfonic acid resin is 700-1300 g/mol, the number average molecular weight is 15-70 ten thousand, and the molecular weight distribution is 1.05-1.8.

6. A method for preparing the sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane according to any one of claims 1 to 5, which is characterized in that: the method comprises the following steps:

(1) mixing sulfonated graphene with a perfluorinated sulfonic acid resin solution, adding DMF, heating to remove water, and finally removing bubbles;

(2) and (2) casting the sulfonated graphene-containing perfluorinated sulfonic acid resin solution obtained in the step (1) into a film by adopting a solution casting method, and drying to obtain the sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane.

7. The preparation method of the sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane according to claim 6, wherein the preparation method comprises the following steps: in the step (1), heating is carried out for 15-24h at 50-100 ℃.

8. The preparation method of the sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane according to claim 6, wherein the preparation method comprises the following steps: in the step (1), the method for removing bubbles is as follows: ultrasonically oscillating the mixed solution for 1.5-2h, and then placing the mixed solution in a vacuum drying oven, wherein the initial temperature is set to be 40-200 ℃.

9. The preparation method of the sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane according to claim 6, wherein the preparation method comprises the following steps: in the step (1), the mixing mode of the sulfonated graphene and the perfluorinated sulfonic acid resin solution is one or more of mechanical stirring, magnetic stirring, ultrasonic oscillation, shearing emulsification or cell crushing.

10. The preparation method of the sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane according to claim 6, wherein the preparation method comprises the following steps: in the step (1), the solution casting method employs one or more of blade coating, slit extrusion, comma blade coating, or meyer bar coating.

Technical Field

The invention relates to a sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane and a preparation method thereof, belonging to the technical field of ion exchange membranes.

Background

The molecular skeleton of the perfluorinated sulfonic acid ion exchange resin is a polytetrafluoroethylene structure, the branched chain is a perfluoropolyether structure, and the end group of the branched chain is a sulfonate group with an ion exchange function. The most important characteristic is that the cation exchange resin has super selectivity and has selective permeability to cations. Among the solid super acids known so far, the perfluorosulfonic acid ion exchange resin is the strongest, and the main reasons for this are: the molecular structure has fluorine atoms with extremely high electronegativity, and can generate a great field effect and an induction effect, so that the molecular structure has extremely high acidity. The perfluorinated sulfonic acid ion exchange resin has excellent chemical stability and is equivalent to polytetrafluoroethylene; the perfluorinated sulfonic acid ion exchange resin has excellent thermal stability, can keep the performance unchanged for a long time at the ambient temperature of about 200 ℃, and is not decomposed or oxidized; the perfluorinated sulfonic acid ion exchange resin has wide use temperature range and meets the use requirements of a plurality of environments; the perfluorosulfonic acid ion exchange resin has excellent mechanical properties, and therefore, is widely applied to the fields of fuel cells, electrolytic water, electrodialysis, flow batteries and the like.

The homogeneous perfluorosulfonic acid ion exchange membrane which is commercially available at present is mainly Nafion series produced by Kemu company, but is high in price. The improvement of the proton conductivity of the perfluorosulfonic acid ion exchange membrane is beneficial to improving the power output of the corresponding electrochemical device. Generally, increasing the ion exchange capacity of the perfluorosulfonic acid resin is an effective method for improving the proton conductivity of the perfluorosulfonic acid ion exchange membrane, but the increase of the ion exchange capacity can significantly improve the dimensional change rate of the perfluorosulfonic acid ion exchange membrane, and finally influences the service life of the ion membrane and the operation safety of an application device. How to improve the proton conductivity of the perfluorosulfonic acid ion exchange membrane on the premise of maintaining the dimensional stability is always the direction of the researchers.

Documents [ Solid State Ionics,2006,177: 1137-; journal of Power Sources,2006,162: 180-; membrane Science,2006,278:35-42, prepares Nafion/mMMT composite membranes using acidified or organically Modified Montmorillonite (MMT), which leads to certain improvement of water and proton conductivity of these composite membranes, but is limited by the characteristics of MMT materials themselves, and its dimensional stability is not good.

In the case of CN20071005167.7, the method comprises the following steps,dissolving ionic polymer into anhydrous solvent to prepare precursor solution, and then dissolving inorganic oxide SiO₂Or TiO₂The precursor compound is added into the precursor solution to prepare a colloidal solution, and then the pH value is adjusted, so that the inorganic oxide is prepared into the inorganic nanoparticle modified composite proton exchange membrane in the colloidal solution, and the water retention performance and the proton conductivity of the proton exchange membrane are improved. Other novel organic-inorganic composite proton exchange membranes improve the proton conductivity of the membrane, but have a large dependence on the water content of the proton membrane, and may have a problem of poor dimensional stability during long-term operation.

CN20151004112.7 introduces benzimidazole structure on polyimide polymer main chain, and uses active N-H structure on imidazolyl group to react with diether cross linker in film forming process to make it cross-link, at the same time adds water-soluble pore-forming agent, obtains porous structure after water immersion, finally casts perfluor sulfonic acid polymer solution on the porous membrane to evaporate solvent to obtain the pore-filling proton exchange membrane.

The patent CN201110139957.0 of the metal research of the Chinese academy of sciences discloses an ion exchange membrane for a reinforced vanadium battery and a preparation method thereof, wherein a nano-carbon material is prepared by a hydrothermal method, then the prepared nano-carbon material containing carboxyl or hydroxyl functional groups is dispersed into a perfluorinated sulfonic acid resin solution, and a casting molding method is adopted. The addition of the nano carbon material obviously improves the proton conductivity and vanadium resistance of the perfluorosulfonic acid ion exchange membrane, but the addition amount of the carbon nano material is limited, and the size stability and strength improvement of the material are limited.

The patent CN 109411796A of Hexagrammos otakii chemical technology Limited discloses a cross-linked proton exchange membrane for a vanadium cell and a preparation method thereof, sulfonated graphene is added into cross-linked sulfonated benzimidazole, and cross-linking is carried out in situ to prepare the cross-linked sulfonated polybenzimidazole proton exchange membrane for the vanadium cell; the addition of the sulfonated graphene remarkably improves the proton conductivity of the cross-linked sulfonated benzimidazole proton exchange membrane, but the chemical stability of the benzimidazole non-fluorine proton exchange membrane needs to be further improved.

Disclosure of Invention

The invention aims to provide a sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane which has high proton conductivity and high mechanical strength; meanwhile, the invention also provides a preparation method which is scientific and reasonable in design, simple and easy to implement.

The sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane is prepared by mixing sulfonated graphene and a perfluorinated sulfonic acid resin solution and then molding by adopting a tape casting method.

Preferably, the content of the sulfonated graphene in the mixed solution is 0.1-20 wt%, the solid content of the perfluorinated sulfonic acid resin solution is 5-40 wt%, and the viscosity is 40-300 cps.

Preferably, the number of sulfonated graphene layers is less than 10, the radial size is 50nm-50 mu m, the thickness is 1-50nm, and the content of S element is 0.1-20 wt%.

The perfluorinated sulfonic acid resin is one or two of long-chain branched perfluorinated sulfonic acid resin or short-chain branched perfluorinated sulfonic acid resin.

Preferably, the EW value of the perfluorinated sulfonic acid resin is 700-1300 g/mol, the number average molecular weight is 15-70 ten thousand, and the molecular weight distribution is 1.05-1.8.

The preparation method of the sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane comprises the following steps:

(1) mixing sulfonated graphene with a perfluorinated sulfonic acid resin solution, adding DMF, heating at 50-100 ℃ for 15-24h for dewatering, and finally removing bubbles;

(2) and (2) casting the sulfonated graphene-containing perfluorinated sulfonic acid resin solution obtained in the step (1) into a film by adopting a solution casting method, and drying to obtain the sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane.

In the step (1), the method for removing bubbles is as follows: ultrasonically oscillating the mixed solution for 1.5-2h, and then placing the mixed solution in a vacuum drying oven, wherein the initial temperature is set to be 40-200 ℃.

In the step (1), the mixing mode of the sulfonated graphene and the perfluorinated sulfonic acid resin solution is one or more of mechanical stirring, magnetic stirring, ultrasonic oscillation, shearing emulsification or cell crushing.

In the step (1), the solution casting method employs one or more of knife coating, slit extrusion, comma knife coating, or Meyer bar coating.

In the step (2), the drying process is segmented drying, the drying process comprises two temperature segments, and the drying temperature is 40-100 ℃ and 100-200 ℃.

The thickness of the sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane prepared by the invention is 5-50 μm.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, the sulfonated graphene is added into the perfluorinated sulfonic acid resin to increase proton transfer channels, so that the resistance of proton transfer is reduced, the conductivity of the perfluorinated sulfonic acid ion exchange membrane can be obviously improved, and the mechanical property of the membrane is improved;

(2) the preparation method of the invention has scientific and reasonable design, is simple and feasible, and is beneficial to industrial production;

(3) the sulfonated graphene modified perfluorinated sulfonic acid ion exchange membrane prepared by the invention is wide in application and is suitable for various fields of fuel cells, water electrolysis, electrodialysis, flow batteries and the like.

Drawings

FIG. 1 is a graph comparing the conductivity of a prepared sulfonated graphene modified perfluorinated ion exchange membrane with that of a conventional membrane;

fig. 2 is a comparison graph of the tensile strength of the prepared sulfonated graphene modified perfluorinated ion exchange membrane and the existing membrane.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the practice of the invention.