Preparation method of an ion exchange composite material for an electrochemical cell

Abstract

The present invention relates to the technical field of ion exchange composite materials, and discloses a preparation method of an ion exchange composite material for an electrochemical cell. 5-Vinylisophthalic acid reacts with epichlorohydrin to obtain dichlorostyrene; through a quaternization reaction in dichlorostyrene, bisquaternary ammonium salt styrene is obtained; alkalized polyvinylidene fluoride, SBS, and bisquaternary ammonium salt styrene are copolymerized under the initiation of benzoyl peroxide to obtain quaternized polyvinylidene fluoride-based SBS. The quaternized polyvinylidene fluoride-based SBS is made into an ion exchange composite material. The ion exchange composite material prepared by the present invention has excellent mechanical properties and electrical conductivity.

Description

Technical Field

[0001] The present invention relates to the technical field of ion exchange composite materials, and particularly to a preparation method of an ion exchange composite material for an electrochemical cell. Background Art

[0002] Anion exchange membranes are a type of ion exchange material. Anion exchange membranes are a class of polymer membranes containing basic active groups and having selective permeability to anions, and are widely used in the chlor-alkali industry, capacitors, batteries and other fields. Quaternary ammonium salts, also known as quaternary ammonium salts, in which the four hydrogen atoms of the ammonium ion are replaced by hydrocarbon groups, have excellent antistatic, bactericidal, and anti-yellowing properties, and are widely used in flocculants, thickeners, antistatic agents and other fields. SBS is a triblock copolymer of styrene and butadiene, having excellent tensile strength, electrical insulation, chemical stability and other properties. The prepared membrane has good flexibility and is widely used in adhesives, rubber products, resin modifiers and other fields.

[0003] Polyvinylidene fluoride (PVDF) is polymerized from 1,1-difluoroethylene, having excellent properties such as anti-aging, weather resistance, and ultraviolet resistance. It is easier to synthesize and form a film than perfluoropolymers and has a lower cost, and is widely used in plastics, coatings, insulating materials, ion exchange membranes and other fields. For example, the patent with the authorized announcement number CN103223307B discloses a preparation method of a polyvinylidene fluoride / polyfatty acid ester-based anion exchange alloy membrane. The prepared anion exchange alloy membrane has a lower resistance, but its mechanical properties are not good. Summary of the Invention

[0004] (1) Technical Problem to be Solved

[0005] Aiming at the deficiencies of the prior art, the present invention provides a preparation method of an ion exchange composite material for an electrochemical cell. The prepared anion exchange membrane has excellent mechanical properties and conductivity.

[0006] (2) Technical Solution

[0007] A preparation method of an ion exchange composite material for an electrochemical cell, the preparation method is as follows:

[0008] (1) Alkalized polyvinylidene fluoride, SBS, bisquaternary ammonium salt styrene, and dibenzoyl peroxide are dissolved in a tetrahydrofuran solution, and reacted at 70-90 °C for 5-10 h, washed with toluene, and dried to obtain quaternized polyvinylidene fluoride-based SBS.

[0009] (2) Dissolve the quaternized polyvinylidene fluoride-based SBS in dimethyl sulfoxide solvent, heat it to 50 - 70 °C, stir for 40 - 80 min, subject the resulting solution to sand filtration, evenly coat it on a horizontal glass plate, dry it to form a film, and finally soak it in sodium chloride solution for 36 - 48 h, then air-dry it to obtain the ion exchange composite material.

[0010] Preferably, in the step (1), the mass ratio of the alkalized polyvinylidene fluoride, SBS, styrene bisquaternary ammonium salt, and dibenzoyl peroxide is 40 - 60:100:25 - 40:0.3 - 0.8.

[0011] Preferably, in the step (2), the molar concentration of the sodium chloride solution is 1 - 1.5 mol / L.

[0012] Preferably, the preparation method of the alkalized polyvinylidene fluoride in the step (1) is as follows:

[0013] (3) Under a nitrogen atmosphere, place polyvinylidene fluoride in an ethanol solution of potassium hydroxide with a concentration of 3 - 5 mol / L, stir to dissolve it, then add an aqueous solution of tetrabutylammonium bromide at 2 - 5 mg / mL, react at 50 - 70 °C for 15 - 30 min, filter, and wash with deionized water to obtain the alkalized polyvinylidene fluoride.

[0014] Preferably, in the step (3), the volume ratio of the ethanol solution of potassium hydroxide to the aqueous solution of tetrabutylammonium bromide is 18 - 25:1.

[0015] Preferably, the preparation method of the styrene bisquaternary ammonium salt in the step (1) is as follows:

[0016] (4) Place 5-vinylisophthalic acid, epichlorohydrin, and benzyltriethylammonium chloride in 1,2-dichloroethane solvent, react at 70 - 90 °C for 2 - 4 h, cool to room temperature, perform vacuum filtration and recrystallization, and dry to obtain styrene dichloride.

[0017] (5) Under nitrogen conditions, place styrene dichloride and cetyl dimethyl tertiary amine in ethanol solvent, stir and react, rotate to evaporate the solvent, and recrystallize with ether to obtain the styrene bisquaternary ammonium salt.

[0018] Preferably, in the step (4), the mass ratio of 5-vinylisophthalic acid, epichlorohydrin, and benzyltriethylammonium chloride is 1:1 - 1.3:0.01 - 0.03.

[0019] Preferably, in the step (5), the mass ratio of styrene dichloride to cetyl dimethyl tertiary amine is 1:0.5 - 0.8.

[0020] Preferably, in the step (5), the stirring reaction time is 15 - 30 h and the temperature is 70 - 90 °C.

[0021] (III) Beneficial technical effects

[0022] The carboxyl group in 5-vinylisophthalic acid reacts with the epoxy group of epichlorohydrin under the catalytic ring-opening of benzyltriethylammonium chloride to obtain styrene dichloride; the quaternization reaction of the double chlorine atoms in styrene dichloride with cetyl dimethyl tertiary amine is used to obtain styrene bisquaternary ammonium salt; polyvinylidene fluoride is alkalized in a mixed solution of potassium hydroxide ethanol solution and tetrabutylammonium bromide aqueous solution to obtain alkalized polyvinylidene fluoride; alkalized polyvinylidene fluoride, SBS, and styrene bisquaternary ammonium salt are copolymerized under the initiation of benzoyl peroxide to obtain quaternized polyvinylidene fluoride-based SBS. Finally, the quaternized polyvinylidene fluoride-based SBS is dissolved in dimethyl sulfoxide solvent, sand-filtered, coated on a horizontal glass plate, and dried to form a film to obtain an ion exchange composite material.

[0023] Both alkalized polyvinylidene fluoride and SBS have alkenyl groups. Then, they are copolymerized with styrene bisquaternary ammonium salt to prepare quaternized polyvinylidene fluoride-based SBS. The polyvinylidene fluoride chain segments and SBS chain segments in it have good compatibility, and the two cross-link with each other to form a huge network structure. When impacted, the stress transfer between the huge cross-linking sites can absorb more energy and improve the mechanical properties of the material.

[0024] The cationic groups therein, namely the quaternary ammonium salt groups, can adsorb negatively charged hydroxide ions through electrostatic adsorption, and can provide jumping active sites for hydroxide ions to support the "jumping" of hydroxide ions from one ion exchange site to another hydroxide ion exchange site, enhancing the directional movement of hydroxide ions, thereby improving the conductivity of the membrane. There are many quaternary ammonium salt groups on the polyvinylidene fluoride chain segments and SBS chain segments. Moreover, as the number of quaternary ammonium groups introduced in the side chain increases, the conductivity of hydroxide ions is higher. In addition, due to the mutual entanglement and cross-linking between the chain segments, there is a large steric hindrance effect, so that under alkaline conditions, the attack of quaternary ammonium cations by hydroxide is weakened, inhibiting the Hofmann elimination reaction, making the quaternized polyvinylidene fluoride-based SBS have strong alkali stability. The ion exchange composite material prepared by the present invention has excellent mechanical properties and conductivity. Description of the Drawings

[0025] Figure 1 is the preparation method of styrene bisquaternary ammonium salt. Detailed Embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0027] Example 1

[0028] (1) Place 6 g of 5-vinylisophthalic acid, 7.2 g of epichlorohydrin, and 0.1 g of benzyltriethylammonium chloride in a 1,2-dichloroethane solvent. React at 80 °C for 3 h, cool to room temperature, filter under reduced pressure, recrystallize, and dry to obtain styrene dichloride.

[0029] (2) Under a nitrogen atmosphere, place 3 g of styrene dichloride and 2 g of cetyl dimethyl tertiary amine in an ethanol solvent. Stir and react at 80 °C for 20 h, rotary evaporate to remove the solvent, and recrystallize with ether to obtain styrene bisquaternary ammonium salt.

[0030] (3) Under a nitrogen atmosphere, place polyvinylidene fluoride in an ethanol solution of potassium hydroxide with a concentration of 4 mol / L, stir to dissolve, and then add an aqueous solution of tetrabutylammonium bromide with a concentration of 4 mg / mL. The volume ratio of the ethanol solution of potassium hydroxide to the aqueous solution of tetrabutylammonium bromide is 20:1. React at 60 °C for 20 min, filter, and wash with deionized water to obtain alkalized polyvinylidene fluoride.

[0031] (4) Dissolve 80 g of alkalized polyvinylidene fluoride, 200 g of SBS, 50 g of styrene bisquaternary ammonium salt, and 1.2 g of dibenzoyl peroxide in a tetrahydrofuran solution. React at 80 °C for 9 h, wash with toluene, and dry to obtain quaternized polyvinylidene fluoride-based SBS.

[0032] (5) Dissolve quaternized polyvinylidene fluoride-based SBS in a dimethyl sulfoxide solvent, heat to 65 °C, stir for 50 min, filter the resulting solution through sand, evenly coat it on a horizontal glass plate, dry to form a film, and finally soak it in a sodium chloride solution with a molar concentration of 1 mol / L for 36 h, and air dry to obtain an ion exchange composite material.

[0033] Example 2

[0034] (1) Place 6 g of 5-vinylisophthalic acid, 7.8 g of epichlorohydrin, and 0.12 g of benzyltriethylammonium chloride in a 1,2-dichloroethane solvent. React at 80 °C for 3 h, cool to room temperature, filter under reduced pressure, recrystallize, and dry to obtain styrene dichloride.

[0035] (2) Under nitrogen conditions, 3 g of styrene dichloride and 2 g of cetyl dimethyl tertiary amine were placed in an ethanol solvent, and stirred at 80 °C for 20 h. The solvent was removed by rotary evaporation and recrystallized with ether to obtain styrene bisquaternary ammonium salt.

[0036] (3) Under a nitrogen atmosphere, polyvinylidene fluoride was placed in an ethanol solution of potassium hydroxide with a concentration of 5 mol / L and stirred to dissolve. Then, an aqueous solution of tetrabutylammonium bromide with a concentration of 4 mg / mL was added thereto, and the volume ratio of the ethanol solution of potassium hydroxide to the aqueous solution of tetrabutylammonium bromide was 18:1. The reaction was carried out at 60 °C for 30 min, filtered, and washed with deionized water to obtain alkalized polyvinylidene fluoride.

[0037] (4) 90 g of alkalized polyvinylidene fluoride, 200 g of SBS, 57.5 g of styrene bisquaternary ammonium salt, and 1.2 g of dibenzoyl peroxide were dissolved in a tetrahydrofuran solution, and the reaction was carried out at 90 °C for 5 h. Then, it was washed with toluene and dried to obtain quaternized polyvinylidene fluoride-based SBS.

[0038] (5) The quaternized polyvinylidene fluoride-based SBS was dissolved in a dimethyl sulfoxide solvent, heated to 60 °C, and stirred for 50 min. The obtained solution was subjected to sand filtration, evenly coated on a horizontal glass plate, dried to form a film, and finally immersed in a sodium chloride solution with a molar concentration of 1.5 mol / L for 48 h and air-dried to obtain an ion exchange composite material.

[0039] Example 3

[0040] (1) 6 g of 5-vinylisophthalic acid, 7 g of epichlorohydrin, and 0.18 g of benzyltriethylammonium chloride were placed in a 1,2-dichloroethane solvent, and the reaction was carried out at 70 °C for 4 h. After cooling to room temperature, it was filtered under reduced pressure, recrystallized, and dried to obtain styrene dichloride.

[0041] (2) Under nitrogen conditions, 3 g of styrene dichloride and 2.4 g of cetyl dimethyl tertiary amine were placed in an ethanol solvent, and stirred at 70 °C for 20 h. The solvent was removed by rotary evaporation and recrystallized with ether to obtain styrene bisquaternary ammonium salt.

[0042] (3) Under a nitrogen atmosphere, polyvinylidene fluoride was placed in an ethanol solution of potassium hydroxide with a concentration of 5 mol / L and stirred to dissolve. Then, an aqueous solution of tetrabutylammonium bromide with a concentration of 2 mg / mL was added thereto, and the volume ratio of the ethanol solution of potassium hydroxide to the aqueous solution of tetrabutylammonium bromide was 22:1. The reaction was carried out at 60 °C for 15 min, filtered, and washed with deionized water to obtain alkalized polyvinylidene fluoride.

[0043] (4) Dissolve 100 g of alkalized polyvinylidene fluoride, 200 g of SBS, 65 g of bisquaternary ammonium salt styrene, and 1.6 g of dibenzoyl peroxide in a tetrahydrofuran solution. React at 70 °C for 6 h, wash with toluene, and dry to obtain quaternized polyvinylidene fluoride-based SBS.

[0044] (5) Dissolve the quaternized polyvinylidene fluoride-based SBS in a dimethyl sulfoxide solvent, heat to 60 °C, stir for 60 min, filter the resulting solution through sand, evenly coat it on a horizontal glass plate, dry to form a film, and finally soak it in a sodium chloride solution with a molar concentration of 1 mol / L for 48 h, then air-dry to obtain an ion exchange composite material.

[0045] Example 4

[0046] (1) Place 6 g of 5-vinylisophthalic acid, 6 g of epichlorohydrin, and 0.18 g of benzyltriethylammonium chloride in a 1,2-dichloroethane solvent. React at 80 °C for 4 h, cool to room temperature, filter under reduced pressure, recrystallize, and dry to obtain styrene dichloride.

[0047] (2) Under nitrogen conditions, place 3 g of styrene dichloride and 1.5 g of cetyl dimethyl tertiary amine in an ethanol solvent. Stir and react at 80 °C for 20 h, remove the solvent by rotary evaporation, and recrystallize with ether to obtain bisquaternary ammonium salt styrene.

[0048] (3) Under a nitrogen atmosphere, place polyvinylidene fluoride in an ethanol solution of potassium hydroxide with a concentration of 5 mol / L, stir to dissolve, and then add an aqueous solution of tetrabutylammonium bromide at 2 mg / mL. The volume ratio of the ethanol solution of potassium hydroxide to the aqueous solution of tetrabutylammonium bromide is 18:1. React at 70 °C for 20 min, filter, and wash with deionized water to obtain alkalized polyvinylidene fluoride.

[0049] (4) Dissolve 110 g of alkalized polyvinylidene fluoride, 200 g of SBS, 72.5 g of bisquaternary ammonium salt styrene, and 1.2 g of dibenzoyl peroxide in a tetrahydrofuran solution. React at 80 °C for 8 h, wash with toluene, and dry to obtain quaternized polyvinylidene fluoride-based SBS.

[0050] (5) Dissolve the quaternized polyvinylidene fluoride-based SBS in a dimethyl sulfoxide solvent, heat to 60 °C, stir for 50 min, filter the resulting solution through sand, evenly coat it on a horizontal glass plate, dry to form a film, and finally soak it in a sodium chloride solution with a molar concentration of 1.2 mol / L for 40 h, then air-dry to obtain an ion exchange composite material.

[0051] Example 5

[0052] (1) 6 g of 5-vinylisophthalic acid, 7 g of epichlorohydrin, and 0.18 g of benzyltriethylammonium chloride were placed in 1,2-dichloroethane solvent and reacted at 80 °C for 4 h. After cooling to room temperature, filtration under reduced pressure, recrystallization, and drying were carried out to obtain styrene dichloride.

[0053] (2) Under nitrogen conditions, 3 g of styrene dichloride and 1.5 g of cetyl dimethyl tertiary amine were placed in ethanol solvent and stirred at 80 °C for 20 h. The solvent was removed by rotary evaporation and recrystallized with ether to obtain styrene bisquaternary ammonium salt.

[0054] (3) Under a nitrogen atmosphere, polyvinylidene fluoride was placed in an ethanol solution of potassium hydroxide with a concentration of 5 mol / L and stirred until dissolved. Then, an aqueous solution of tetrabutylammonium bromide with a concentration of 4 mg / mL was added, and the volume ratio of the ethanol solution of potassium hydroxide to the aqueous solution of tetrabutylammonium bromide was 25:1. The reaction was carried out at 60 °C for 25 min, followed by filtration and washing with deionized water to obtain alkalized polyvinylidene fluoride.

[0055] (4) 120 g of alkalized polyvinylidene fluoride, 200 g of SBS, 80 g of styrene bisquaternary ammonium salt, and 1.5 g of dibenzoyl peroxide were dissolved in tetrahydrofuran solution and reacted at 80 °C for 8 h. After washing with toluene and drying, quaternized polyvinylidene fluoride-based SBS was obtained.

[0056] (5) The quaternized polyvinylidene fluoride-based SBS was dissolved in dimethyl sulfoxide solvent, heated to 60 °C, and stirred for 70 min. The resulting solution was filtered through sand, evenly spread on a horizontal glass plate, dried to form a film, and finally immersed in a sodium chloride solution with a molar concentration of 1 mol / L for 45 h and air-dried to obtain an ion exchange composite material.

[0057] Comparative Example 1

[0058] (1) Under a nitrogen atmosphere, polyvinylidene fluoride was placed in an ethanol solution of potassium hydroxide with a concentration of 4 mol / L and stirred until dissolved. Then, an aqueous solution of tetrabutylammonium bromide with a concentration of 4 mg / mL was added, and the volume ratio of the ethanol solution of potassium hydroxide to the aqueous solution of tetrabutylammonium bromide was 20:1. The reaction was carried out at 60 °C for 20 min, followed by filtration and washing with deionized water to obtain alkalized polyvinylidene fluoride.

[0059] (2) 80 g of alkalized polyvinylidene fluoride, 200 g of SBS, and 1.2 g of dibenzoyl peroxide were dissolved in tetrahydrofuran solution and reacted at 80 °C for 9 h. After washing with toluene and drying, polyvinylidene fluoride-based SBS was obtained.

[0060] (3) Dissolve polyvinylidene fluoride-based SBS in dimethyl sulfoxide solvent, heat it to 65 °C, stir for 50 min, filter the resulting solution through sand filtration, evenly coat it on a horizontal glass plate, dry to form a film, and finally soak it in a sodium chloride solution with a molar concentration of 1 mol / L for 36 h, then air dry to obtain an ion exchange composite material.

[0061] Comparative Example 2

[0062] (1) Place 6 g of 5-vinylisophthalic acid, 7.2 g of epichlorohydrin, and 0.1 g of benzyltriethylammonium chloride in 1,2-dichloroethane solvent, react at 80 °C for 3 h, cool to room temperature, filter under reduced pressure, recrystallize, and dry to obtain styrene dichloride.

[0063] (2) Under nitrogen atmosphere, place 3 g of styrene dichloride and 2 g of cetyl dimethyl tertiary amine in ethanol solvent, stir and react at 80 °C for 20 h, remove the solvent by rotary evaporation, recrystallize with ether to obtain bisquaternary ammonium salt styrene.

[0064] (3) Dissolve 200 g of SBS, 50 g of bisquaternary ammonium salt styrene, and 1.2 g of dibenzoyl peroxide in tetrahydrofuran solution, react at 80 °C for 9 h, wash with toluene, and dry to obtain quaternized SBS.

[0065] (4) Dissolve quaternized SBS in dimethyl sulfoxide solvent, heat it to 65 °C, stir for 50 min, filter the resulting solution through sand filtration, evenly coat it on a horizontal glass plate, dry to form a film, and finally soak it in a sodium chloride solution with a molar concentration of 1 mol / L for 36 h, then air dry to obtain an ion exchange composite material.

[0066] Use a universal material testing machine to test the mechanical properties of the materials.

[0067] Tensile strength (MPa) Elongation at break (%) Example 1 39.1 11.26 Example 2 45.3 13.19 Example 3 53.0 15.62 Example 4 61.5 20.86 Example 5 55.3 18.20 Comparative Example 1 36.8 10.92 Comparative Example 2 32.6 10.01

[0068] The mechanical properties of Examples 1-5 and Comparative Example 1 are better than those of Comparative Example 2. This is because the product added in Examples 1-5 and Comparative Example 1 is the blend crosslinking product of alkalized polyvinylidene fluoride and SBS. Both the alkalized polyvinylidene fluoride and SBS chain segments have alkenyl groups, and they also have good compatibility after crosslinking copolymerization. The two crosslink and copolymerize with each other to form a huge network structure. When subjected to impact, the stress transfer between the huge crosslinking sites can absorb more energy and improve the mechanical properties of the material. While in Comparative Example 2, it is only the copolymerization product of SBS and bisquaternary ammonium salt styrene, and its mechanical properties are not as good as the blend crosslinking effect of polyvinylidene fluoride and SBS, so its mechanical properties are poor.

[0069] The membrane was immersed in a 0.01 mol / L sodium hydroxide solution for two days, washed with deionized water until neutral, dried, 0.5 g of the membrane was weighed, cut into pieces and soaked in a 0.1 mol / L hydrochloric acid aqueous solution for 24 h. Using phenolphthalein as a reagent, it was titrated with a 0.1 mol / L sodium hydroxide solution to calculate the ion exchange capacity value (IEC).

[0070] IEC = (A - B) / W; A is the initial number of moles of HCl, B is the remaining number of moles of HCl, and W is the mass of the membrane.

[0071] An electrolytic cell with an electrolyte of 0.1 mol / L sodium chloride aqueous solution was used to measure the resistance between the two electrodes to calculate the membrane surface resistance.

[0072] R = (C - D) × S. R is the membrane surface resistance (Ω·cm 2 ), C is the resistance value of the electrolyte between the two electrodes with the membrane, D is the resistance value without the membrane, and S is the effective area of the membrane.

[0073] IEC / (mmol / g) <![CDATA[Sheet Resistance / Ω·cm 2 > Example 1 0.91 11.00 Example 2 1.25 8.16 Example 3 1.56 5.23 Example 4 2.10 3.16 Example 5 1.76 4.98 Comparative Example 1 0.62 13.25 Comparative Example 2 1.05 10.23

[0074] The ion exchange capacity values of Examples 1 - 5 and Comparative Example 2 are larger than those of Comparative Example 1, and the surface resistances of Examples 1 - 5 and Comparative Example 2 are smaller than those of Comparative Example 1. This is because Examples 1 - 5 and Comparative Example 2 contain more positively charged quaternary ammonium salt groups. The more positively charged quaternary ammonium salt groups, the greater the hydrophilicity, the larger its ion exchange capacity value, and the smaller the surface resistance. And the smaller the surface resistance, the greater its conductivity. Therefore, the ion exchange capacity values of Examples 1 - 5 and Comparative Example 2 are larger than those of Comparative Example 1, and the conductivities of Examples 1 - 5 and Comparative Example 2 are more excellent than those of Comparative Example 1.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an ion exchange composite material for an electrochemical cell, characterized in that, The preparation method is as follows: (1) Dissolve alkalized polyvinylidene fluoride, SBS, styrene bisquaternary ammonium salt, and benzoyl peroxide in a tetrahydrofuran solution, react at 70 - 90 °C for 5 - 10 h, wash with toluene, and dry to obtain quaternized polyvinylidene fluoride-based SBS; (2) Dissolve quaternized polyvinylidene fluoride-based SBS in a dimethyl sulfoxide solvent, heat up to 50 - 70 °C, stir for 40 - 80 min, filter the resulting solution through sand filtration, evenly coat it on a horizontal glass plate, dry to form a film, and finally soak it in a sodium chloride solution for 36 - 48 h, and air dry to obtain an ion exchange composite material; The preparation method of the alkalized polyvinylidene fluoride is as follows: (3) Under a nitrogen atmosphere, place polyvinylidene fluoride in an ethanol solution of potassium hydroxide with a concentration of 3 - 5 mol / L, stir to dissolve, then add an aqueous solution of tetrabutylammonium bromide at 2 - 5 mg / mL, react at 50 - 70 °C for 15 - 30 min, filter, and wash with deionized water to obtain alkalized polyvinylidene fluoride; The preparation method of the styrene bisquaternary ammonium salt is as follows: (4) Place 5-vinylisophthalic acid, epichlorohydrin, and benzyltriethylammonium chloride in a 1,2-dichloroethane solvent, react at 70 - 90 °C for 2 - 4 h, cool to room temperature, perform vacuum filtration and recrystallization, and dry to obtain styrene dichloride; (5) Under nitrogen conditions, place styrene dichloride and cetyl dimethyl tertiary amine in an ethanol solvent, stir and react, rotary evaporate to remove the solvent, and recrystallize with ether to obtain styrene bisquaternary ammonium salt.

2. The preparation method of an ion exchange composite material for an electrochemical cell according to claim 1, characterized in that, In step (1), the mass ratio of alkalized polyvinylidene fluoride, SBS, styrene bisquaternary ammonium salt, and benzoyl peroxide is 40 - 60:100:25 - 40:0.3 - 0.

8.

3. The preparation method of an ion exchange composite material for an electrochemical cell according to claim 1, characterized in that, In step (2), the molar concentration of the sodium chloride solution is 1 - 1.5 mol / L.

4. The preparation method of an ion exchange composite material for an electrochemical cell according to claim 1, characterized in that, In step (3), the volume ratio of the ethanol solution of potassium hydroxide to the aqueous solution of tetrabutylammonium bromide is 18 - 25:

1.

5. The preparation method of an ion exchange composite material for an electrochemical cell according to claim 1, characterized in that, In step (4), the mass ratio of 5-vinylisophthalic acid, epichlorohydrin, and benzyltriethylammonium chloride is 1:1 - 1.3:0.01 - 0.

03.

6. The preparation method of an ion exchange composite material for an electrochemical cell according to claim 1, characterized in that, In step (5), the mass ratio of styrene dichloride and cetyl dimethyl tertiary amine is 1:0.5 - 0.

8.

7. A method for preparing an ion exchange composite material for an electrochemical cell according to claim 1, characterized in that, In step (5), the stirring reaction time is 15 - 30 h, and the temperature is 70 - 90 °C.

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