A graphene-based electrolyte material, a preparation method and application on a nickel-zinc battery

Abstract

The application relates to the technical field of secondary batteries, and discloses a graphene-based electrolyte material, a preparation method and application in a nickel-zinc battery. The graphene-based electrolyte material is prepared by the following steps: reacting amino-modified graphene oxide with an ionic liquid monomer containing a vinyl group and an epoxy group to prepare ionic liquid-modified graphene oxide, introducing the ionic liquid-modified graphene oxide as a polymerization monomer into a sodium allyl sulfonate and acrylamide to carry out a free radical copolymerization reaction, and the graphene-based electrolyte material has high water retention and excellent electrochemical performance. When the graphene-based electrolyte material is used as a solid electrolyte of a nickel-zinc battery, the cycle stability of the battery can be effectively improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of secondary batteries, in particular to a graphene-based electrolyte material, a preparation method and application in a nickel-zinc battery. BACKGROUND

[0002] Nickel-zinc secondary batteries are widely used due to high specific power, high specific energy, high discharge voltage platform and wide working temperature range. However, compared with other secondary batteries, the nickel-zinc secondary battery has the problems of short cycle life and easy decay of discharge capacity, which is due to the dissolution of active material zinc oxide and the growth of zinc dendrites. During the charging process, zinc ions are deposited unevenly on the negative electrode surface to form dendritic crystals, and with the increase of the cycle number, the dendrites continuously grow and may pierce the separator, resulting in a short circuit of the battery.

[0003] The introduction of graphene and its composite materials into the polymer electrolyte can significantly improve the ionic conductivity, mechanical strength and electrochemical stability of the electrolyte. However, the graphene material is prone to agglomeration in the polymer matrix, which affects the comprehensive performance of the material. The hydrogel electrolyte is a kind of polymer electrolyte, which is composed of a cross-linked network and hydrophilic polymer chains, and fills the solvent water in the pores to dissolve zinc salt. The high water content makes the hydrogel electrolyte have a certain degree of soft wetness, which ensures that it can dissolve different types of zinc salt to form ideal hydrogel electrolyte, has good physical flexibility, suitable ionic conductivity and excellent mechanical properties, and can inhibit the side reaction of the zinc negative electrode and the growth of metal dendrites by reducing the content of free water in the electrolyte.

[0004] Therefore, it is necessary to take into account the advantages of hydrogel electrolyte and graphene material, and to prepare an electrolyte material containing graphene, which is applied to a nickel-zinc secondary battery to improve the cycle stability of the battery. SUMMARY

[0005] The application aims at overcoming the defects of the prior art, and provides a graphene-based electrolyte material, a preparation method and application in a nickel-zinc battery. The amino-modified graphene oxide is reacted with an ionic liquid monomer containing a vinyl group and an epoxy group to prepare ionic liquid-modified graphene oxide, which is introduced into a radical copolymerization reaction of sodium allyl sulfonate and acrylamide as a polymerization monomer, so that the graphene-based electrolyte material has high water retention and excellent ionic conductivity, and when the graphene-based electrolyte material is used as a solid electrolyte of a nickel-zinc battery, the cycle stability of the battery can be effectively improved.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0007] A preparation method of a graphene-based electrolyte material, comprising the following steps:

[0008] Step (1): Mix graphene oxide and N,N-dimethylformamide, disperse by ultrasonication, add triethylenetetramine and dicyclohexylcarboimide, continue ultrasonic dispersion and reaction, after the reaction is completed, add ethanol and let stand, filter to take the precipitate, wash with ethanol and water in sequence, dry to obtain amino-modified graphene oxide.

[0009] Step (2): Mix the ionic liquid monomer and amino-modified graphene oxide, disperse by ultrasonication, and react. After the reaction is completed, ionic liquid-modified graphene oxide is obtained.

[0010] The ionic liquid monomer is prepared by the following steps:

[0011] S1. Epichlorohydrin and water were mixed, and vinylimidazole was added dropwise. After the addition was complete, the reaction was carried out. After the reaction was completed, the solvent was removed by vacuum distillation, and the product was washed with ethyl acetate and dried to obtain 1-vinyl-3-epoxypropylimidazolium chloride.

[0012] S2. Dissolve 1-vinyl-3-epoxypropylimidazolium chloride and zinc bis(trifluoromethanesulfonyl)imide in water respectively. Add the zinc bis(trifluoromethanesulfonyl)imide aqueous solution dropwise to the aqueous solution of 1-vinyl-3-epoxypropylimidazolium chloride. After the addition is complete, the reaction is carried out. After the reaction is completed, the solution is filtered, washed with water, and dried to obtain the ionic liquid monomer.

[0013] Step (3): Add sodium allyl sulfonate to water, stir and mix, add acrylamide and ionic liquid modified graphene oxide, ultrasonically disperse, add N,N'-methylenebisacrylamide and stir, add ammonium persulfate aqueous solution, stir, and polymerize to obtain a graphene-based electrolyte material.

[0014] Preferably, in step (1), the solid-liquid ratio of graphene oxide, triethylenetetramine, dicyclohexylcarboimide, and N,N-dimethylformamide is 0.2g:20-40g:2-6g:100-300mL; the reaction conditions are: reaction at 110-120℃ for 48h.

[0015] Preferably, in step (2), the mass ratio of ionic liquid monomer to amino-modified graphene oxide is 4-4.8:0.2-1; the reaction conditions are: stirring at 50-60℃ for 4-6 hours.

[0016] Preferably, in step (2), when preparing the ionic liquid monomer, the molar ratio of epichlorohydrin to vinylimidazole in S1 is 1-1.2:1; the dropping conditions for vinylimidazole are: dropping for 1 hour in a nitrogen atmosphere at 50-60°C; and the reaction conditions are: reacting for 3-5 hours in a nitrogen atmosphere at 50-60°C.

[0017] Preferably, in the preparation of the ionic liquid monomer in step (2), in S2: the molar ratio of 1-vinyl-3-epoxypropyl imidazole chloride to zinc bis(trifluoromethyl sulfonyl) imide is 1:1; the concentration of the aqueous solution of zinc bis(trifluoromethyl sulfonyl) imide and the aqueous solution of 1-vinyl-3-epoxypropyl imidazole chloride is 15-20wt%; the dropwise addition condition is: dropwise addition at room temperature for 0.5-1h; the reaction condition is: stirring reaction at room temperature for 20-26h.

[0018] Preferably, in step (3): the mass ratio of sodium allyl sulfonate, acrylamide, ionic liquid modified graphene oxide, N,N'-methylene bisacrylamide, and aqueous ammonium persulfate solution is 35-36:24-25:8-10:0.25:25; the concentration of the aqueous ammonium persulfate solution is 20wt%; the addition condition of the aqueous ammonium persulfate solution is: addition at a temperature of 0-5℃ and stirring for 20-30min; the polymerization reaction condition is: polymerization reaction at a temperature of 50-60℃ for 5-7h.

[0019] Preferably, the graphene-based electrolyte material is prepared by the preparation method of the graphene-based electrolyte material.

[0020] Preferably, the graphene-based electrolyte material is applied to a nickel-zinc battery.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] 1、The amino-modified graphene oxide is reacted with the ionic liquid monomer containing vinyl and epoxy to prepare ionic liquid modified graphene oxide, which is introduced into sodium allyl sulfonate and acrylamide for free radical copolymerization to prepare the graphene-based electrolyte material, which has high water retention and excellent electrochemical performance, and when the graphene-based electrolyte material is used as a solid-state electrolyte of a nickel-zinc battery, the cycle stability of the battery can be effectively improved.

[0023] 2、The application utilizes the reaction of the carboxyl group of the graphene oxide sheet layer with the amino group in triethylenetetramine under the catalysis of dicyclohexyl carbodiimide to graft triethylenetetramine on the graphene oxide to obtain amino-modified graphene oxide, which is reacted with the ionic liquid monomer to prepare ionic liquid modified graphene oxide, which improves the dispersibility of the graphene oxide in the electrolyte material and improves the ionic conductivity and water retention performance of the electrolyte material by the characteristics of the ionic liquid;

[0024] The ionic liquid monomer is obtained by the reaction of epichlorohydrin and vinyl imidazole, and the anion TFSI -The prepared electrolyte material has two active functional groups of vinyl and epoxy groups, the epoxy group can undergo ring-opening reaction with amino-modified graphene oxide, and the vinyl group can participate in the radical polymerization reaction of sodium allyl sulfonate and acrylamide, so that the components are uniformly dispersed in the electrolyte material.

[0025] 3、The present application utilizes radical copolymerization of sodium allyl sulfonate, acrylamide and ionic liquid-modified graphene oxide to form a gel with a cross-linked structure, the sulfonic acid group and the ionic liquid-modified graphene oxide have affinity for cations and water molecules, which can synergistically improve the water retention performance, ionic conductivity and zinc ion transference number of the material, inhibit the generation of zinc dendrites, and improve the cycle stability of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a water retention rate column chart of the graphene-based electrolyte material prepared in Examples 1-5 and Comparative Examples 1-2 in the performance test in the present application;

[0027] Figure 2 is a ion transference number line chart of the graphene-based electrolyte material prepared in Examples 1-5 and Comparative Examples 1-2 in the performance test in the present application;

[0028] Figure 3 is a reaction schematic diagram of 1-vinyl-3-epoxypropyl imidazole chloride prepared in the present application. DETAILED DESCRIPTION

[0029] The present application will be further described in detail through specific embodiments, the following examples are specific embodiments of the present application, but the embodiments of the present application are not limited by the following examples, any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application, all should be equivalent replacement methods, and are included in the protection scope of the present application.

[0030] Example 1

[0031] The present embodiment discloses a preparation method of a graphene-based electrolyte material, comprising the following steps:

[0032] Step (1), mix graphene oxide and N,N-dimethylformamide, ultrasonic dispersion for 3h, add triethylenetetramine and dicyclohexyl carbodiimide, continue to ultrasonic dispersion for 5min, react at 120℃ for 48h, after the reaction is completed, add ethanol and stand for 8h, filter and take the precipitate, wash with ethanol and water in turn, dry at 70℃ for 12h, to obtain amino-modified graphene oxide;

[0033] The solid-liquid ratio of graphene oxide, triethylenetetramine, dicyclohexyl carbodiimide, and N,N-dimethylformamide is 0.2 g:30 g:5 g:200 mL;

[0034] Step (2), the ionic liquid monomer and the amino-modified graphene oxide are mixed in a mass ratio of 4.8:0.2, ultrasonic dispersion is performed for 5 min, stirring reaction is performed at 60°C for 4 h, and after the reaction is completed, the ionic liquid-modified graphene oxide is obtained;

[0035] The ionic liquid monomer is prepared by the following steps:

[0036] S1, epoxy chloropropane and water are mixed in a mass ratio of 1:2, vinyl imidazole is added dropwise in a nitrogen atmosphere at 60°C, the dropwise addition time is 1 h, after the dropwise addition is completed, reaction is performed at 60°C for 3 h, after the reaction is completed, the solvent is removed by reduced pressure distillation, washing is performed with ethyl acetate, and drying is performed at 40°C for 12 h to obtain 1-vinyl-3-epoxypropyl imidazole chloride;

[0037] The molar ratio of epoxy chloropropane and vinyl imidazole is 1:1.

[0038] S2, 1-vinyl-3-epoxypropyl imidazole chloride is dissolved in water to obtain a 20wt% 1-vinyl-3-epoxypropyl imidazole chloride aqueous solution; zinc bis(trifluoromethylsulfonyl) imide (Zn(TFSI)2) is dissolved in water to obtain a 20wt% zinc bis(trifluoromethylsulfonyl) imide aqueous solution; the zinc bis(trifluoromethylsulfonyl) imide aqueous solution is added dropwise into the 1-vinyl-3-epoxypropyl imidazole chloride aqueous solution at room temperature, the dropwise addition time is 1 h, after the dropwise addition is completed, stirring reaction is performed at room temperature for 24 h, after the reaction is completed, filtration is performed, washing is performed with water, and drying is performed at 40°C for 12 h to obtain the ionic liquid monomer;

[0039] The molar ratio of 1-vinyl-3-epoxypropyl imidazole chloride and zinc bis(trifluoromethylsulfonyl) imide is 1:1.

[0040] Step (3), sodium allyl sulfonate is added to water, stirring and mixing are performed for 30 min, acrylamide and the ionic liquid-modified graphene oxide are added, ultrasonic dispersion is performed for 1 h, N,N'-methylene bisacrylamide is added and stirring is performed for 3 h, a 20wt% ammonium persulfate aqueous solution is added at 2°C, stirring is performed for 20 min, and the electrolyte material based on graphene is obtained by polymerization reaction at 60°C for 5 h in a mold.

[0041] The mass ratio of sodium allyl sulfonate, acrylamide, the ionic liquid-modified graphene oxide, N,N'-methylene bisacrylamide, and the 20wt% ammonium persulfate aqueous solution is 35:25:8:0.25:25.

[0042] Example 2

[0043] The embodiment discloses a preparation method of a graphene-based electrolyte material, comprising the following steps:

[0044] Step (1), graphene oxide, N,N-dimethylformamide are mixed, ultrasonic dispersion is carried out for 3h, triethylenetetramine and dicyclohexyl carbodiimide are added, ultrasonic dispersion is continuously carried out for 5min, reaction is carried out at 120 DEG C for 48h, after the reaction is completed, ethanol is added and is placed for 8h, the precipitate is obtained by filtration, and the precipitate is washed with ethanol and water in sequence, and is dried at 70 DEG C for 12h, so that amino-modified graphene oxide is obtained;

[0045] In the embodiment, the solid-liquid ratio of graphene oxide, triethylenetetramine, dicyclohexyl carbodiimide and N,N-dimethylformamide is 0.2g:30g:5g:200mL;

[0046] Step (2), the ionic liquid monomer and the amino-modified graphene oxide are mixed in a mass ratio of 4.6:0.4, ultrasonic dispersion is carried out for 5min, stirring reaction is carried out at 60 DEG C for 4h, after the reaction is completed, ionic liquid-modified graphene oxide is obtained;

[0047] In the embodiment, the ionic liquid monomer is prepared by the following steps:

[0048] S1, epoxy chloropropane and water are mixed in a mass ratio of 1:2, vinyl imidazole is added dropwise in a nitrogen atmosphere at 60 DEG C, the dropwise adding time is 1h, after the dropwise adding is completed, reaction is carried out at 60 DEG C for 3h, after the reaction is completed, the solvent is removed by reduced pressure distillation, the obtained product is washed with ethyl acetate, and is dried at 40 DEG C for 12h, so that 1-vinyl-3-epoxypropyl imidazole chloride salt is obtained;

[0049] In the embodiment, the molar ratio of epoxy chloropropane and vinyl imidazole is 1:1;

[0050] S2, 1-vinyl-3-epoxypropyl imidazole chloride salt is dissolved in water to obtain a 20wt% 1-vinyl-3-epoxypropyl imidazole chloride salt aqueous solution; zinc bis(trifluoromethylsulfonyl) imide (Zn(TFSI)2) is dissolved in water to obtain a 20wt% zinc bis(trifluoromethylsulfonyl) imide aqueous solution; the zinc bis(trifluoromethylsulfonyl) imide aqueous solution is added dropwise into the 1-vinyl-3-epoxypropyl imidazole chloride salt aqueous solution at room temperature, the dropwise adding time is 1h, after the dropwise adding is completed, stirring reaction is carried out at room temperature for 24h, after the reaction is completed, filtration is carried out, washing is carried out with water, and drying is carried out at 40 DEG C for 12h, so that the ionic liquid monomer is obtained;

[0051] In the embodiment, the molar ratio of 1-vinyl-3-epoxypropyl imidazole chloride salt and zinc bis(trifluoromethylsulfonyl) imide is 1:1;

[0052] Step (3), sodium allyl sulfonate was added into water, stirred and mixed for 30 min, acrylamide and ionic liquid modified graphene oxide were added, ultrasonic dispersion was carried out for 1 h, N,N'-methylene bisacrylamide was added and stirred for 3 h, 20 wt% ammonium persulfate aqueous solution was added at a temperature of 2℃, stirred for 20 min, placed in a mold and polymerization reaction was carried out at a temperature of 60℃ for 5 h to obtain a graphene-based electrolyte material;

[0053] The mass ratio of sodium allyl sulfonate, acrylamide, ionic liquid modified graphene oxide, N,N'-methylene bisacrylamide and 20 wt% ammonium persulfate aqueous solution is 35.3:24.7:8.5:0.25:25.

[0054] Example 3

[0055] The embodiment discloses a preparation method of a graphene-based electrolyte material, comprising the following steps:

[0056] Step (1), graphene oxide and N,N-dimethylformamide were mixed and ultrasonic dispersion was carried out for 3 h, triethylenetetramine and dicyclohexyl carbodiimide were added and ultrasonic dispersion was continued for 5 min, reaction was carried out at a temperature of 120℃ for 48 h, after the reaction was completed, ethanol was added and stood for 8 h, the precipitate was taken after filtration, washed with ethanol and water in sequence, and dried at a temperature of 70℃ for 12 h to obtain amino-modified graphene oxide;

[0057] The solid-liquid ratio of graphene oxide, triethylenetetramine, dicyclohexyl carbodiimide and N,N-dimethylformamide is 0.2 g:30 g:5 g:200 mL;

[0058] Step (2), ionic liquid monomer and amino-modified graphene oxide were mixed in a mass ratio of 4.4:0.6, ultrasonic dispersion was carried out for 5 min, and stirring reaction was carried out at a temperature of 60℃ for 4 h, after the reaction was completed, ionic liquid modified graphene oxide was obtained;

[0059] The ionic liquid monomer is prepared by the following steps:

[0060] S1, epoxy chloropropane and water were mixed in a mass ratio of 1:2, vinyl imidazole was added dropwise in a nitrogen atmosphere at a temperature of 60℃, the dropwise adding time was 1 h, after the dropwise adding was completed, reaction was carried out at a temperature of 60℃ for 3 h, after the reaction was completed, the solvent was removed by reduced pressure distillation, washed with ethyl acetate, and dried at a temperature of 40℃ for 12 h to obtain 1-vinyl-3-epoxypropyl imidazole chloride;

[0061] The molar ratio of epoxy chloropropane and vinyl imidazole is 1:1;

[0062] S2, dissolving 1-vinyl-3-epoxypropyl imidazole chloride salt in water to obtain a 20wt% 1-vinyl-3-epoxypropyl imidazole chloride salt aqueous solution; dissolving zinc bis(trifluoromethylsulfonyl)imide (Zn(TFSI)2) in water to obtain a 20wt% zinc bis(trifluoromethylsulfonyl)imide aqueous solution; adding the zinc bis(trifluoromethylsulfonyl)imide aqueous solution dropwise into the 1-vinyl-3-epoxypropyl imidazole chloride salt aqueous solution at room temperature, the dropping time being 1h, after the dropping is completed, stirring and reacting at room temperature for 24h, after the reaction is completed, filtering, washing with water, and drying at a temperature of 40℃ for 12h to obtain an ionic liquid monomer;

[0063] wherein the molar ratio of 1-vinyl-3-epoxypropyl imidazole chloride salt to zinc bis(trifluoromethylsulfonyl)imide is 1:1;

[0064] Step (3), adding sodium allyl sulfonate into water, stirring and mixing for 30min, adding acrylamide and ionic liquid modified graphene oxide, ultrasonic dispersion for 1h, adding N,N'-methylene bisacrylamide, stirring for 3h, adding 20wt% ammonium persulfate aqueous solution at a temperature of 2℃, stirring for 20min, placing in a mold, and polymerizing at a temperature of 60℃ for 5h to obtain a graphene-based electrolyte material;

[0065] wherein the mass ratio of sodium allyl sulfonate, acrylamide, ionic liquid modified graphene oxide, N,N'-methylene bisacrylamide, and 20wt% ammonium persulfate aqueous solution is 35.5:24.5:9:0.25:25.

[0066] Example 4

[0067] The embodiment discloses a preparation method of a graphene-based electrolyte material, comprising the following steps:

[0068] Step (1), mixing graphene oxide and N,N-dimethylformamide, ultrasonic dispersion for 3h, adding triethylenetetramine and dicyclohexyl carbodiimide, continuing ultrasonic dispersion for 5min, reacting at a temperature of 120℃ for 48h, after the reaction is completed, adding ethanol and standing for 8h, filtering and taking the precipitate, washing with ethanol and water in sequence, and drying at a temperature of 70℃ for 12h to obtain amino-modified graphene oxide;

[0069] wherein the solid-liquid ratio of graphene oxide, triethylenetetramine, dicyclohexyl carbodiimide, and N,N-dimethylformamide is 0.2g:30g:5g:200mL;

[0070] Step (2), mixing the ionic liquid monomer and the amino-modified graphene oxide in a mass ratio of 4.2:0.8, ultrasonic dispersion for 5min, stirring and reacting at a temperature of 60℃ for 4h, after the reaction is completed, obtaining ionic liquid modified graphene oxide;

[0071] The ionic liquid monomer is prepared by the following steps:

[0072] S1, mixing epichlorohydrin and water in a mass ratio of 1:2, adding vinyl imidazole dropwise in a nitrogen atmosphere at a temperature of 60°C, the dropwise adding time being 1h, after the dropwise adding is completed, reacting at a temperature of 60°C for 3h, after the reaction is completed, removing the solvent by reduced pressure distillation, washing with ethyl acetate, and drying at a temperature of 40°C for 12h to obtain 1-vinyl-3-epoxypropyl imidazole chloride;

[0073] The molar ratio of epichlorohydrin to vinyl imidazole is 1:1.

[0074] S2, dissolving 1-vinyl-3-epoxypropyl imidazole chloride in water to obtain a 20wt% 1-vinyl-3-epoxypropyl imidazole chloride aqueous solution; dissolving zinc bis(trifluoromethylsulfonyl) imide (Zn(TFSI)2) in water to obtain a 20wt% zinc bis(trifluoromethylsulfonyl) imide aqueous solution; adding the zinc bis(trifluoromethylsulfonyl) imide aqueous solution dropwise into the 1-vinyl-3-epoxypropyl imidazole chloride aqueous solution at room temperature, the dropwise adding time being 1h, after the dropwise adding is completed, stirring and reacting at room temperature for 24h, after the reaction is completed, filtering, washing with water, and drying at a temperature of 40°C for 12h to obtain the ionic liquid monomer;

[0075] The molar ratio of 1-vinyl-3-epoxypropyl imidazole chloride to zinc bis(trifluoromethylsulfonyl) imide is 1:1.

[0076] Step (3), adding sodium allyl sulfonate into water, stirring and mixing for 30min, adding acrylamide and ionic liquid modified graphene oxide, ultrasonic dispersing for 1h, adding N,N'-methylene bisacrylamide, stirring for 3h, adding 20wt% ammonium persulfate aqueous solution at a temperature of 2°C, stirring for 20min, placing in a mold, and polymerizing at a temperature of 60°C for 5h to obtain the graphene-based electrolyte material;

[0077] The mass ratio of sodium allyl sulfonate, acrylamide, ionic liquid modified graphene oxide, N,N'-methylene bisacrylamide, and 20wt% ammonium persulfate aqueous solution is 35.8:24.2:9.5:0.25:25.

[0078] Example 5

[0079] The embodiment discloses a preparation method of a graphene-based electrolyte material, comprising the following steps:

[0080] Step (1), mix graphene oxide and N,N-dimethylformamide, ultrasonic dispersion for 3h, add triethylenetetramine and dicyclohexyl carbodiimide, continue to ultrasonic dispersion for 5min, react at 120℃ for 48h, after the reaction is completed, add ethanol and stand for 8h, filter and take the precipitate, wash with ethanol and water in turn, dry at 70℃ for 12h to obtain amino-modified graphene oxide;

[0081] Wherein, the solid-liquid ratio of graphene oxide, triethylenetetramine, dicyclohexyl carbodiimide and N,N-dimethylformamide is 0.2g:30g:5g:200mL;

[0082] Step (2), mix ionic liquid monomer and amino-modified graphene oxide at a mass ratio of 4:1, ultrasonic dispersion for 5min, stir and react at 60℃ for 4h, after the reaction is completed, obtain ionic liquid modified graphene oxide;

[0083] Wherein, the ionic liquid monomer is prepared by the following steps:

[0084] S1, mix epichlorohydrin and water at a mass ratio of 1:2, add vinyl imidazole dropwise under nitrogen atmosphere at 60℃, the dropwise adding time is 1h, after the dropwise adding is completed, react at 60℃ for 3h, after the reaction is completed, remove the solvent by reduced pressure distillation, wash with ethyl acetate, and dry at 40℃ for 12h to obtain 1-vinyl-3-epoxypropyl imidazole chloride;

[0085] Wherein, the molar ratio of epichlorohydrin and vinyl imidazole is 1:1;

[0086] S2, dissolve 1-vinyl-3-epoxypropyl imidazole chloride in water to obtain a 20wt% 1-vinyl-3-epoxypropyl imidazole chloride aqueous solution; dissolve zinc bis(trifluoromethylsulfonyl) imide (Zn(TFSI)2) in water to obtain a 20wt% zinc bis(trifluoromethylsulfonyl) imide aqueous solution; add the zinc bis(trifluoromethylsulfonyl) imide aqueous solution dropwise into the 1-vinyl-3-epoxypropyl imidazole chloride aqueous solution at room temperature, the dropwise adding time is 1h, after the dropwise adding is completed, stir and react at room temperature for 24h, after the reaction is completed, filter, wash with water, and dry at 40℃ for 12h to obtain the ionic liquid monomer;

[0087] Wherein, the molar ratio of 1-vinyl-3-epoxypropyl imidazole chloride and zinc bis(trifluoromethylsulfonyl) imide is 1:1;

[0088] Step (3), sodium allyl sulfonate was added to water, stirred and mixed for 30 min, acrylamide and ionic liquid modified graphene oxide were added, ultrasonic dispersion was performed for 1 h, N,N'-methylene bisacrylamide was added and stirred for 3 h, 20 wt% ammonium persulfate aqueous solution was added at a temperature of 2°C, stirring was performed for 20 min, and the mixture was placed in a mold and polymerization was performed at a temperature of 60°C for 5 h to obtain a graphene-based electrolyte material;

[0089] The mass ratio of sodium allyl sulfonate, acrylamide, ionic liquid modified graphene oxide, N,N'-methylene bisacrylamide, and 20 wt% ammonium persulfate aqueous solution is 36:24:10:0.25:25.

[0090] Comparative Example 1

[0091] The present comparative example discloses a preparation method of a graphene-based electrolyte material, comprising the following steps:

[0092] Step (1), graphene oxide and N,N-dimethylformamide were mixed and ultrasonic dispersion was performed for 3 h, triethylenetetramine and dicyclohexyl carbodiimide were added and ultrasonic dispersion was continued for 5 min, reaction was performed at a temperature of 120°C for 48 h, after the reaction was completed, ethanol was added and left to stand for 8 h, the precipitate was collected by filtration, and the precipitate was washed with ethanol and water in sequence and dried at a temperature of 70°C for 12 h to obtain amino-modified graphene oxide;

[0093] The solid-liquid ratio of graphene oxide, triethylenetetramine, dicyclohexyl carbodiimide, and N,N-dimethylformamide is 0.2 g:30 g:5 g:200 mL.

[0094] Step (2), sodium allyl sulfonate was added to water, stirred and mixed for 30 min, acrylamide and graphene oxide were added, ultrasonic dispersion was performed for 1 h, N,N'-methylene bisacrylamide was added and stirred for 3 h, 20 wt% ammonium persulfate aqueous solution was added at a temperature of 2°C, stirring was performed for 20 min, and the mixture was placed in a mold and polymerization was performed at a temperature of 60°C for 5 h to obtain a graphene-based electrolyte material;

[0095] The mass ratio of sodium allyl sulfonate, acrylamide, graphene oxide, N,N'-methylene bisacrylamide, and 20 wt% ammonium persulfate aqueous solution is 35:25:0.32:0.25:25.

[0096] Comparative Example 2

[0097] The present comparative example discloses a preparation method of a graphene-based electrolyte material, comprising the following steps:

[0098] Step (1), an ionic liquid monomer and graphene oxide were mixed at a mass ratio of 4.8:0.2, ultrasonic dispersion was performed for 5 min to obtain an ionic liquid / graphene oxide mixture;

[0099] The ionic liquid monomer is prepared by the following steps:

[0100] S1, mixing epichlorohydrin and water at a mass ratio of 1:2, adding vinyl imidazole dropwise under a nitrogen atmosphere at a temperature of 60°C, the dropwise adding time being 1 h, after the dropwise adding is completed, reacting at a temperature of 60°C for 3 h, after the reaction is completed, removing the solvent by reduced pressure distillation, washing with ethyl acetate, and drying at a temperature of 40°C for 12 h to obtain 1-vinyl-3-epoxypropyl imidazole chloride;

[0101] The molar ratio of epichlorohydrin to vinyl imidazole is 1:1.

[0102] S2, dissolving 1-vinyl-3-epoxypropyl imidazole chloride in water to obtain a 20 wt% 1-vinyl-3-epoxypropyl imidazole chloride aqueous solution; dissolving zinc bis(trifluoromethylsulfonyl) imide (Zn(TFSI)2) in water to obtain a 20 wt% zinc bis(trifluoromethylsulfonyl) imide aqueous solution; adding the zinc bis(trifluoromethylsulfonyl) imide aqueous solution dropwise into the 1-vinyl-3-epoxypropyl imidazole chloride aqueous solution at room temperature, the dropwise adding time being 1 h, after the dropwise adding is completed, stirring and reacting at room temperature for 24 h, after the reaction is completed, filtering, washing with water, and drying at a temperature of 40°C for 12 h to obtain the ionic liquid monomer;

[0103] The molar ratio of 1-vinyl-3-epoxypropyl imidazole chloride to zinc bis(trifluoromethylsulfonyl) imide is 1:1.

[0104] Step (3), adding sodium allyl sulfonate into water, stirring and mixing for 30 min, adding acrylamide and the ionic liquid / graphene oxide mixture, ultrasonic dispersing for 1 h, adding N,N'-methylene bisacrylamide, stirring for 3 h, adding a 20 wt% ammonium persulfate aqueous solution at a temperature of 2°C, stirring for 20 min, and placing in a mold to perform polymerization reaction at a temperature of 60°C for 5 h to obtain the graphene-based electrolyte material;

[0105] The mass ratio of sodium allyl sulfonate, acrylamide, the ionic liquid / graphene oxide mixture, N,N'-methylene bisacrylamide, and the 20 wt% ammonium persulfate aqueous solution is 35:25:8:0.25:25.

[0106] In the above examples and comparative examples, the graphene oxide is commercially available.

[0107] Test Example

[0108] The graphene-based electrolyte materials prepared in Examples 1-5 and Comparative Examples 1-2 are subjected to comprehensive performance testing. The specific test results are shown in Table 1.

[0109] Table 1

[0110] Water retention (%) Ionic conductivity (S / cm) Ionic transference number Example 1 91.2 5.66 x 10 -4 ]]> 0.72 Example 2 91.4 5.91 x 10 -4 ]] 0.73 Example 3 91.6 6.43 x 10 -4 ]] 0.75 Example 4 91.9 7.09 x 10 -4 ]] 0.77 Example 5 92.1 7.52 x 10 -4 ]]> 0.78 Comparative Example 1 85.1 1.21 x 10 -4 ]]> 0.52 Comparative Example 2 91.1 3.11 x 10 -4 ]] 0.64

[0111] The detection of each index in Table 1 is based on the following standards: the test method of water retention rate is as follows: placing Examples 1-5 and Comparative Examples 1-2 in water, standing at room temperature for 4 h, taking out, standing at room temperature in an open system for 10 days, and then measuring the water retention rate; the ion conductivity is tested by electrochemical impedance spectroscopy, the test model is stainless steel electrode / electrolyte material / stainless steel electrode, the test frequency range is 100 mHz to 100 kHz, and the amplitude is 5 mV; the ion transference number is tested by direct polarization method, the test model is metal zinc sheet / electrolyte / metal zinc sheet, the applied voltage is 10 mV, and the polarization time is 3600 s.

[0112] According to the test results in Table 1, the graphene-based electrolyte material prepared in the application has high water retention and excellent electrochemical performance. This is because the introduction of ionic liquid modified graphene oxide in the electrolyte material improves the dispersibility of graphene oxide in the electrolyte material, and on the other hand, the characteristics of ionic liquid improve the ion conductivity and water retention performance of the electrolyte material. At the same time, the sulfonic acid groups in the electrolyte material and the ionic liquid modified graphene oxide have affinity for cations and water molecules, which can synergistically improve the water retention performance, ion conductivity and zinc ion transference number of the material, inhibit the generation of zinc dendrites, and improve the cycle stability of the battery.

[0113] Comparative Example 1 does not add ionic liquid, and lacks the effect of ionic liquid on improving the water retention performance and electrochemical performance of the electrolyte material, so the performance of Comparative Example 1 is not as good as that of the examples;

[0114] Comparative Example 2 does not modify the surface of graphene oxide with amino groups, and graphene oxide is easy to agglomerate in the electrolyte material, which affects the electrochemical performance of the material, so the ion conductivity and ion transference number of Comparative Example 2 are not as good as those of the examples.

[0115] It should be noted that the above examples are only used to explain the application and do not constitute any limitation on the application. The application has been described by referring to typical examples, but it should be understood that the words used therein are descriptive and explanatory words, not limiting words. The application can be modified as specified within the scope of the claims of the application, and the application can be revised without departing from the scope and spirit of the application. Although the application described therein relates to specific methods, materials and examples, it does not mean that the application is limited to the specific examples disclosed therein, on the contrary, the application can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing a graphene-based electrolyte material, characterized in that, Includes the following steps: Step (1): Add the aqueous solution of zinc bis(trifluoromethanesulfonyl)imide dropwise to the aqueous solution of 1-vinyl-3-epoxypropylimidazolium chloride. After the addition is complete, the reaction is carried out. After the reaction is completed, the mixture is filtered, washed, and dried to obtain the ionic liquid monomer. Step (2): Mix the ionic liquid monomer and amino-modified graphene oxide, disperse by ultrasonication, and react. After the reaction is completed, ionic liquid-modified graphene oxide is obtained. Step (3): Add sodium allyl sulfonate to water, stir and mix, add acrylamide and ionic liquid modified graphene oxide, ultrasonically disperse, add N,N'-methylenebisacrylamide and stir, add ammonium persulfate aqueous solution, stir, and polymerize to obtain a graphene-based electrolyte material.

2. The method for preparing a graphene-based electrolyte material according to claim 1, characterized in that, In step (1), 1-vinyl-3-epoxypropylimidazolium chloride is prepared by the following steps: Epichlorohydrin and water were mixed, and vinylimidazole was added dropwise. After the addition was complete, the reaction was carried out. After the reaction was completed, the solvent was removed by vacuum distillation, and the product was washed with ethyl acetate and dried to obtain 1-vinyl-3-epoxypropylimidazolium chloride.

3. The method for preparing a graphene-based electrolyte material according to claim 2, characterized in that, In step (1), when preparing 1-vinyl-3-epoxypropylimidazolium chloride, the molar ratio of epichlorohydrin to vinylimidazolium is 1-1.2:1; the dropping conditions for vinylimidazolium are: dropping for 1 hour at 50-60°C under a nitrogen atmosphere; and the reaction conditions are: reacting for 3-5 hours at 50-60°C under a nitrogen atmosphere.

4. The method for preparing a graphene-based electrolyte material according to claim 1, characterized in that, In step (1): the concentrations of the aqueous solution of bis(trifluoromethanesulfonyl)imide zinc and the aqueous solution of 1-vinyl-3-epoxypropylimidazolium chloride are both 15-20 wt%; the molar ratio of 1-vinyl-3-epoxypropylimidazolium chloride to bis(trifluoromethanesulfonyl)imide zinc is 1:1; the dropping conditions are: dropping at room temperature for 0.5-1 h; the reaction conditions are: stirring at room temperature for 20-26 h.

5. The method for preparing a graphene-based electrolyte material according to claim 1, characterized in that, In step (2), the amino-modified graphene oxide is prepared by the following steps: Graphene oxide and N,N-dimethylformamide were mixed and ultrasonically dispersed. Triethylenetetramine and dicyclohexylcarboimide were added, and ultrasonic dispersion was continued. After the reaction was completed, ethanol was added and allowed to stand. The precipitate was filtered and washed with ethanol and water in sequence, and then dried to obtain amino-modified graphene oxide.

6. The method for preparing a graphene-based electrolyte material according to claim 5, characterized in that, In step (2), when preparing amino-modified graphene oxide, the solid-liquid ratio of graphene oxide, triethylenetetramine, dicyclohexylcarboimide, and N,N-dimethylformamide is 0.2g:20-40g:2-6g:100-300mL; the reaction conditions are: reaction at 110-120℃ for 48h.

7. The method for preparing a graphene-based electrolyte material according to claim 1, characterized in that, In step (2), the mass ratio of ionic liquid monomer to amino-modified graphene oxide is 4-4.8:0.2-1; the reaction conditions are: stirring at 50-60℃ for 4-6 hours.

8. The method for preparing a graphene-based electrolyte material according to claim 1, characterized in that, In step (3), the mass ratio of sodium allyl sulfonate, acrylamide, ionic liquid modified graphene oxide, N,N'-methylenebisacrylamide, and ammonium persulfate aqueous solution is 35-36:24-25:8-10:0.25:25; the concentration of ammonium persulfate aqueous solution is 20wt%; the conditions for adding ammonium persulfate aqueous solution are: adding at 0-5℃ and stirring for 20-30min; the polymerization reaction conditions are: polymerization reaction at 50-60℃ for 5-7h.

9. A graphene-based electrolyte material prepared by the method for preparing a graphene-based electrolyte material as described in any one of claims 1-8.

10. The application of the graphene-based electrolyte material as described in claim 9 in a nickel-zinc battery.

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