High-temperature-resistant and high-stability supercapacitor and preparation method thereof

Abstract

The application discloses a high-temperature-resistant and high-stability super capacitor and a preparation method thereof, and relates to the technical field of high-temperature-resistant capacitors.In the application, polyimide acid solution is added into slurry to improve the high-temperature resistance of positive and negative electrode sheets and the adhesion between the slurry and the electrode sheets, reduce the shedding of active materials in the charging and discharging process, and improve the cycle life of the battery; polyacrylonitrile powder, a flame retardant and the like are used as raw materials to prepare a spinning liquid, electrostatic spinning is carried out, and a polyacrylonitrile fiber diaphragm with good flame retardance and mechanical properties is obtained; the positive and negative electrode sheets and the diaphragm are wound, and an electrolyte is injected to obtain the high-temperature-resistant, long-cycle-life and high-stability super capacitor.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of high-temperature capacitors, in particular to a high-temperature-resistant and high-stability super capacitor and a preparation method thereof. BACKGROUND

[0002] The super capacitor, also known as a gold capacitor, a farad capacitor or an electrochemical capacitor, is a new energy storage device between a traditional capacitor and a rechargeable battery, and has the characteristics of fast charging and discharging of the capacitor and energy storage of the battery; the super capacitor does not have a chemical reaction in the process of energy storage, the energy storage process is reversible, and has the advantages of long cycle period, fast charging and discharging, high power, high safety and the like.

[0003] The highest working temperature of a traditional large-capacity double-layer super capacitor is generally 65 DEG C, and when operating under a high-temperature condition (such as 100 DEG C or more), a series of significant technical defects exist, and it is difficult to meet the requirements of the thermal stability and reliability of the device in harsh application scenarios such as high-temperature industries, aerospace, oil and gas exploration and electric vehicle motor compartments; the commonly used organic electrolyte has poor thermal stability, is easy to decompose, expand and even leak under high temperature, and seriously affects the electrochemical performance and safety of the device; the diaphragm material is mostly a polyolefin polymer, and is easy to shrink and melt in a high-temperature environment, and has the risk of internal short circuit; the interface contact between the electrode and the current collector is easy to age and peel off under high temperature, resulting in the increase of internal resistance and the attenuation of cycle performance; the traditional packaging structure has insufficient heat resistance, and is easy to have problems such as the decrease of air tightness and mechanical deformation in a high-temperature environment, thereby affecting the long-term stable operation of the device.

[0004] Therefore, it is urgent to develop a new super capacitor with high thermal stability, including a matched high-temperature-resistant electrode material, an electrolyte system, a diaphragm assembly and a packaging structure, so as to solve the problems of poor safety, insufficient reliability and short service life of the prior art in a high-temperature use scenario. SUMMARY

[0005] The application aims to provide a high-temperature-resistant and high-stability super capacitor and a preparation method thereof, so as to solve the problems in the prior art.

[0006] To achieve the above-mentioned purpose, the application provides the following technical scheme: a preparation method of a high-temperature-resistant and high-stability super capacitor, comprising the following steps:

[0007] Step 1: uniformly mixing graphene, SuperP (super conductive carbon black), a polyimide acid solution and deionized water to obtain a slurry, coating the slurry on an aluminum foil and a copper foil respectively, drying, and then performing imidization to obtain a positive electrode sheet and a negative electrode sheet respectively;

[0008] Step 2, polyacrylonitrile powder, N,N-dimethylformamide are mixed, heated in water bath, then flame retardant is added, stirred uniformly, to obtain a spinning solution, and the spinning solution is electrospun to obtain a polyacrylonitrile fiber diaphragm;

[0009] Step 3, the positive plate, the polyacrylonitrile fiber diaphragm, and the negative plate are laminated in sequence, and then are wound to obtain a battery core, which is placed in a shell, and then electrolyte is injected to obtain a supercapacitor.

[0010] Further, in step 1, the mass ratio of the graphene, SuperP, polyimide acid solution, and deionized water is 10: (0.5-1.5): (1.5-2.5): (20-30).

[0011] Further, in step 1, the thickness of the aluminum foil is 10-14 μm.

[0012] The thickness of the copper foil is 10-14 μm.

[0013] The coating thickness of the slurry is 20-40 μm.

[0014] Further, in step 1, the drying process conditions are as follows: temperature 120-140 ℃, time 1-2 h.

[0015] The imidization process conditions are as follows: temperature 280-300 ℃, time 3-4 h.

[0016] Further, in step 2, the mass ratio of the polyacrylonitrile powder, N,N-dimethylformamide, and flame retardant is (1.0-1.4): 10: (0.15-0.25).

[0017] Further, in step 2, the water bath heating process conditions are as follows: temperature 50-60 ℃, time 2.6-3.0 h.

[0018] Further, in step 2, the electrospinning process conditions are as follows: spinning voltage 18-22 kV, spinning solution flow rate 0.3-0.5 mL / h, receiving distance 10-15 cm, spinning time 2.5-3.5 h, and roller speed 800-1000 r / min.

[0019] Further, in step 3, the electrolyte comprises the following components: 55-65% ethylene glycol, 20-30% deionized water, 6-10% ammonium formate, 0.5-0.7% phosphate, 0.6-1.0% polyvinyl alcohol, 4-6% tributylamine, 0.5-0.7% p-nitrobenzyl alcohol, and 2.5-3.5% ammonium dihydrogen phosphate, in terms of mass percentage.

[0020] Further, in step 1, the polyimide acid solution is prepared by the following process:

[0021] Mix 2,3-diamino fluorobenzene, N-methyl pyrrolidone, diethylene triamine pentaacetic acid dianhydride, and then stir and react under the protection of nitrogen atmosphere, and then add 1,1-bis(4-cyanophenoxy)ethane to obtain a polyimide acid solution.

[0022] Further, the mass ratio of 2,3-diamino fluorobenzene, N-methyl pyrrolidone, diethylene triamine pentaacetic acid dianhydride, and 1,1-bis(4-cyanophenoxy)ethane is 10:(90-110):(12-16):(2.0-2.6).

[0023] Further, the process condition of stirring and reaction is that the temperature is 20-40℃, and the time is 2-6h.

[0024] Further, in step 2, the flame retardant is prepared by the following process:

[0025] S1: Mix 2-amino-6-hydroxybenzothiazole, ethanol, and 3-hydroxy-2-pyridine formaldehyde, stir and react under heating, cool, and dry to obtain an imine bond-containing compound;

[0026] S2: Mix DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and ethanol, ultrasonic treatment, then add the imine bond-containing compound, oil bath heating and stirring reaction, and cool to obtain the flame retardant.

[0027] Further, in S1, the ratio of 2-amino-6-hydroxybenzothiazole, ethanol, and 3-hydroxy-2-pyridine formaldehyde is (1.0-1.5)g:10mL:(1.0-1.4)g.

[0028] Further, in S1, the process condition of heating and stirring reaction is that the temperature is 75-85℃, and the time is 8-10h.

[0029] Further, in S2, the ratio of DOPO, ethanol, and the imine bond-containing compound is (8-12)g:100mL:(10-14)g.

[0030] Further, in S2, the process condition of oil bath heating and stirring reaction is that the temperature is 80-85℃, the time is 10-12h, and the stirring speed is 100-120r / min.

[0031] Compared with the prior art, the beneficial effects of the present application are:

[0032] 1. In this invention, 2,3-diaminofluorobenzene undergoes an acylation reaction with diethylenetriaminepentaacetic dianhydride, followed by the addition of 1,1-bis(4-cyanooxyphenyl)ethane. The cyanate ester group reacts with the carboxyl group of diethylenetriaminepentaacetic dianhydride to generate a fluorine-containing, amide-containing modified polyimide acid. The cyanate ester group can form stable covalent bonds with the hydroxyl groups on the surface of aluminum foil and copper foil. By adding modified polyimide acid to the slurry, the high-temperature resistance of the positive and negative electrodes and the adhesion between the slurry and the electrodes can be improved, reducing the shedding of active materials during charging and discharging and improving the cycle life of the battery. Compared with traditional binders, the modified polyimide acid, after imidization treatment, has better high-temperature resistance and strong chemical inertness, making it less susceptible to corrosion and protecting the electrodes from erosion.

[0033] 2. In this invention, the polyacrylonitrile fiber diaphragm also has excellent mechanical properties and high voltage performance, giving the capacitor good cycle stability and making it less prone to shrinkage, melting and other phenomena; however, polyacrylonitrile fiber is a flammable material, therefore, a flame retardant is added to the spinning solution raw material to make it flame retardant.

[0034] The amino group of 2-amino-6-hydroxybenzothiazole undergoes a condensation reaction with the aldehyde group of 3-hydroxy-2-pyridinecarboxaldehyde to generate a compound containing an imine bond. The imine bond undergoes nucleophilic addition to the PH bond of DOPO to obtain a flame retardant containing nitrogen, phosphorus, and sulfur elements. The hydroxyl group does not participate in the reaction, meaning the flame retardant also contains hydroxyl groups. This is then blended with raw materials such as polyacrylonitrile powder to prepare a spinning solution, followed by electrospinning to obtain a polyacrylonitrile fiber membrane rich in hydroxyl groups. The hydroxyl groups have strong polarity, which can enhance the wettability of the membrane with the electrolyte, allowing it to be quickly wetted by the electrolyte, reducing the interfacial resistance to ion migration, and improving ion conduction efficiency. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In the following specific implementation;

[0037] Graphene, 2nm thick, 5μm in diameter;

[0038] SuperP, model TOB-SUP-P, is from Shenzhen Liyou New Energy Technology Co., Ltd.

[0039] Polyacrylonitrile powder, molecular weight 80,000;

[0040] Polyvinylidene fluoride powder, with an average particle size of 5 μm;

[0041] Polypropylene diaphragm, from Nantong Jianghai Energy Storage Technology Co., Ltd.

[0042] Embodiment 1: a preparation method of a high-temperature-resistant and high-stability supercapacitor, comprising the following steps:

[0043] (1) Preparation of polyimide acid solution:

[0044] 2,3-diamino fluorobenzene, N-methyl pyrrolidone, diethylene triamine pentaacetic acid dianhydride were mixed, stirred and reacted under the protection of nitrogen atmosphere, then 1,1-bis(4-cyanophenoxy)ethane was added to obtain a polyimide acid solution; the mass ratio of 2,3-diamino fluorobenzene, N-methyl pyrrolidone, diethylene triamine pentaacetic acid dianhydride and 1,1-bis(4-cyanophenoxy)ethane was 10:110:16:2.6; the process conditions for stirring and reaction were as follows: temperature 40℃, time 6h;

[0045] (2) Preparation of flame retardant:

[0046] S1: 2-amino-6-hydroxybenzothiazole, ethanol, 3-hydroxy-2-pyridine formaldehyde were mixed, heated and stirred to react, then cooled and dried to obtain an imine bond-containing compound; S2: DOPO and ethanol were mixed and ultrasonically treated, then the imine bond-containing compound was added, oil bath heating and stirring were performed, and then cooled to obtain a flame retardant; in S1, the ratio of 2-amino-6-hydroxybenzothiazole, ethanol and 3-hydroxy-2-pyridine formaldehyde was 1.5g:10mL:1.4g; in S1, the process conditions for heating and stirring were as follows: temperature 85℃, time 10h; in S2, the ratio of DOPO, ethanol and the imine bond-containing compound was 12g:100mL:14g; in S2, the process conditions for oil bath heating and stirring were as follows: temperature 85℃, time 12h, stirring speed 120r / min;

[0047] (3) Preparation of supercapacitor:

[0048] Step 1, mix graphene, SuperP, polyimide acid solution, deionized water uniformly to obtain a slurry, respectively coat the slurry on aluminum foil and copper foil, dry, then perform imidization to respectively obtain positive electrode sheet and negative electrode sheet; Step 2, mix polyacrylonitrile powder and N,N-dimethylformamide, heat in water bath, then add flame retardant, stir uniformly to obtain spinning solution, electrospun to obtain polyacrylonitrile fiber diaphragm; Step 3, stack the positive electrode sheet, polyacrylonitrile fiber diaphragm and negative electrode sheet in sequence, wind to obtain an electric core, put into a shell, inject electrolyte to obtain a super capacitor; in Step 1, the mass ratio of graphene, SuperP, polyimide acid solution and deionized water is 10:1.5:2.5:30; in Step 1, the thickness of aluminum foil is 14 μm; the thickness of copper foil is 14 μm; the coating thickness of the slurry is 40 μm; in Step 1, the process conditions of drying are: temperature 140℃, time 2h; the process conditions of imidization are: temperature 300℃, time 4h; in Step 2, the mass ratio of polyacrylonitrile powder, N,N-dimethylformamide and flame retardant is 1.4:10:0.25; in Step 2, the process conditions of heating in water bath are: temperature 60℃, time 3.0h; in Step 2, the process conditions of electrospinning are: spinning voltage 22kV, spinning solution flow rate 0.5mL / h, receiving distance 15cm, spinning time 3.5h, roller speed 1000r / min; in Step 3, the electrolyte comprises the following components: 65% ethylene glycol, 20% deionized water, 6% ammonium formate, 0.5% phosphate, 0.6% polyvinyl alcohol, 4% tributylamine, 0.5% p-nitrobenzyl alcohol, 3.4% ammonium dihydrogen phosphate, by mass percentage.

[0049] Embodiment 2: a preparation method of a super capacitor with high temperature resistance and high stability, comprising the following steps:

[0050] (1) preparation of polyimide acid solution:

[0051] mix 2,3-diamino fluorobenzene, N-methyl pyrrolidone and diethylene triamine pentaacetic dianhydride, stir and react under nitrogen atmosphere protection, then add 1,1-bis(4-cyanophenoxy)ethane to obtain polyimide acid solution; the mass ratio of 2,3-diamino fluorobenzene, N-methyl pyrrolidone, diethylene triamine pentaacetic dianhydride and 1,1-bis(4-cyanophenoxy)ethane is 10:100:14:2.3; the process conditions of stirring and reaction are: temperature 30℃, time 4h;

[0052] (2) preparation of flame retardant:

[0053] S1: 2-amino-6-hydroxybenzothiazole, ethanol, 3-hydroxy-2-pyridine carboxaldehyde are mixed, heated and stirred to react, cooled and dried to obtain an imine bond-containing compound; S2: DOPO and ethanol are mixed, ultrasonic treatment is performed, and then the imine bond-containing compound is added, oil bath heating and stirring are performed to react, and then cooled to obtain a flame retardant; in S1, the ratio of 2-amino-6-hydroxybenzothiazole, ethanol and 3-hydroxy-2-pyridine carboxaldehyde is 1.3g:10mL:1.2g; in S1, the process conditions for heating and stirring to react are: temperature 80℃, time 90h; in S2, the ratio of DOPO, ethanol and the imine bond-containing compound is 10g:100mL:12g; in S2, the process conditions for oil bath heating and stirring to react are: temperature 83℃, time 11h, stirring speed 110r / min;

[0054] (3) Preparation of the supercapacitor:

[0055] Step 1: graphene, SuperP, polyimide acid solution and deionized water are uniformly mixed to obtain a slurry, the slurry is coated on an aluminum foil and a copper foil respectively, dried, and then imidized to obtain a positive electrode sheet and a negative electrode sheet respectively; Step 2: polyacrylonitrile powder and N,N-dimethylformamide are mixed, water bath heating is performed, then the flame retardant is added and stirred uniformly to obtain a spinning solution, and then electrospinning is performed to obtain a polyacrylonitrile fiber separator; Step 3: the positive electrode sheet, the polyacrylonitrile fiber separator and the negative electrode sheet are laminated in sequence, wound to obtain an electric core, placed in a shell, and then an electrolyte is injected to obtain a supercapacitor; in Step 1, the mass ratio of graphene, SuperP, polyimide acid solution and deionized water is 10:1.0:2.0:25; in Step 1, the thickness of the aluminum foil is 12μm; the thickness of the copper foil is 12μm; the coating thickness of the slurry is 30μm; in Step 1, the process conditions for drying are: temperature 130℃, time 1.5h; the process conditions for imidization are: temperature 290℃, time 3.5h; in Step 2, the mass ratio of polyacrylonitrile powder, N,N-dimethylformamide and the flame retardant is 1.2:10:0.20; in Step 2, the process conditions for water bath heating are: temperature 55℃, time 2.8h; in Step 2, the process conditions for electrospinning are: spinning voltage 20kV, spinning solution flow rate 0.4mL / h, receiving distance 13cm, spinning time 3.0h, and roller speed 900r / min; in Step 3, the electrolyte comprises the following components: 60% ethylene glycol, 24% deionized water, 6% ammonium formate, 0.6% phosphate, 0.8% polyvinyl alcohol, 5% tributylamine, 0.6% p-nitrobenzyl alcohol and 3.0% ammonium dihydrogen phosphate.

[0056] Example 3: A preparation method of a supercapacitor with high temperature resistance and high stability, comprising the following steps:

[0057] (1) Preparation of a polyimide acid solution:

[0058] 2,3-diaminofluorobenzene, N-methylpyrrolidone, diethylenetriamine pentaacetic acid dianhydride were mixed, stirred under the protection of nitrogen atmosphere, then 1,1-bis(4-cyanophenoxy)ethane was added to obtain a polyimide acid solution; the mass ratio of 2,3-diaminofluorobenzene, N-methylpyrrolidone, diethylenetriamine pentaacetic acid dianhydride and 1,1-bis(4-cyanophenoxy)ethane was 10:90:12:2.0; the process conditions for stirring reaction were as follows: temperature 20℃, time 2h;

[0059] (2) Preparation of the flame retardant:

[0060] S1: 2-amino-6-hydroxybenzothiazole, ethanol, 3-hydroxy-2-pyridine formaldehyde were mixed and stirred under heating, then cooled and dried to obtain an imine bond-containing compound; S2: DOPO and ethanol were mixed and ultrasonically treated, then the imine bond-containing compound was added and stirred under oil bath heating, then cooled to obtain the flame retardant; in S1, the ratio of 2-amino-6-hydroxybenzothiazole, ethanol and 3-hydroxy-2-pyridine formaldehyde was 1.0g:10mL:1.0g; in S1, the process conditions for stirring under heating were as follows: temperature 75℃, time 8h; in S2, the ratio of DOPO, ethanol and the imine bond-containing compound was 8g:100mL:10g; in S2, the process conditions for stirring under oil bath heating were as follows: temperature 80℃, time 10h, stirring speed 100r / min;

[0061] (3) Preparation of the supercapacitor:

[0062] Step 1, mix graphene, SuperP, polyimide acid solution, deionized water uniformly to obtain a slurry, respectively coat the slurry on aluminum foil and copper foil, dry, then carry out imidization to respectively obtain positive electrode sheet and negative electrode sheet; Step 2, mix polyacrylonitrile powder and N,N-dimethylformamide, heat in water bath, then add flame retardant, stir uniformly to obtain spinning solution, electrospun to obtain polyacrylonitrile fiber diaphragm; Step 3, stack the positive electrode sheet, polyacrylonitrile fiber diaphragm and negative electrode sheet in sequence, wind to obtain an electric core, put into a shell, inject electrolyte to obtain a supercapacitor; in Step 1, the mass ratio of graphene, SuperP, polyimide acid solution and deionized water is 10:0.5:1.5:20; in Step 1, the thickness of aluminum foil is 10 μm; the thickness of copper foil is 10 μm; the coating thickness of the slurry is 20 μm; in Step 1, the process conditions of drying are: temperature 120℃, time 1h; the process conditions of imidization are: temperature 280℃, time 3h; in Step 2, the mass ratio of polyacrylonitrile powder, N,N-dimethylformamide and flame retardant is 1.0:10:0.15; in Step 2, the process conditions of water bath heating are: temperature 50℃, time 2.6h; in Step 2, the process conditions of electrospinning are: spinning voltage 18kV, spinning solution flow rate 0.3mL / h, receiving distance 10cm, spinning time 2.5h, roller speed 800r / min; in Step 3, the electrolyte comprises the following components: 55% ethylene glycol, 28% deionized water, 8% ammonium formate, 0.7% phosphate, 0.8% polyvinyl alcohol, 4% tributylamine, 0.5% p-nitrobenzyl alcohol, 3.0% ammonium dihydrogen phosphate, by mass percentage.

[0063] Comparative Example 1: taking Example 1 as a comparison, replace polyimide acid solution with polyvinylidene fluoride powder, and the rest of the conditions remain unchanged.

[0064] Comparative Example 2: taking Example 1 as a comparison, do not add flame retardant in the spinning solution, and the rest of the conditions remain unchanged.

[0065] Comparative Example 3: taking Example 1 as a comparison, replace polyacrylonitrile fiber diaphragm with polypropylene diaphragm, and the rest of the conditions remain unchanged.

[0066] Comparative Example 4: taking Example 1 as a comparison, replace polyimide acid solution with polyvinylidene fluoride powder, replace polyacrylonitrile fiber diaphragm with polypropylene diaphragm, and do not add flame retardant in the spinning solution, and the rest of the conditions remain unchanged.

[0067] Experiment: take the polyacrylonitrile fiber diaphragm and supercapacitor obtained in the examples and comparative examples to test their performance.

[0068] Super capacitor performance test: according to GB / T 34870.1-2017, the super capacitors obtained in the examples and comparative examples were tested for various performances, the environmental temperature was set to 120℃, and the cycle number at which the capacity retention rate was 90% was recorded;

[0069] Separation membrane performance test: according to GB / T12914-2018, the tensile strength of the polyacrylonitrile fiber separation membrane obtained was tested;

[0070] Thermal dimensional stability test: the polyacrylonitrile fiber separation membrane was cut into a circular sample with a diameter of 15 mm, the circular sample was placed in a 120℃ air drying oven for heating for 1h, and the shrinkage rate of the separation membrane was tested;

[0071] Take the polyacrylonitrile fiber separation membrane, weigh and record as W w , the sample was immersed in the electrolyte for 3h, after taking out, the surface residual electrolyte was removed, and then weighed and recorded as W d , the liquid absorption rate was calculated;

[0072] The liquid absorption rate calculation formula is as follows: ;

[0073] Flame retardant test method: take the polyacrylonitrile fiber separation membrane, cut into a 1x5cm strip sample, vertically fix the sample in the combustion cylinder, ignite the sample, record the afterflame time and damage length within the limit time, test the oxygen index (LOI) size, record LOI <20% as flammable, LOI = 20~26% as combustible, LOI = 26~34 as difficult to burn, and LOI >35% as non-flammable;

[0074] Table 1 Super capacitor performance test results

[0075] ;

[0076] Table 2 Separation membrane performance test results

[0077]

[0078] According to the results in the above table, compared with Example 1, Comparative Example 1 replaces the polyimide acid solution with polyvinylidene fluoride powder, and the performance of the obtained super capacitor decreases, because compared with the traditional binder, the modified polyimide acid is treated by imidization, and has better high temperature resistance and strong chemical inertness, and is not easy to be corroded;

[0079] Comparative Example 2 does not add a flame retardant in the spinning solution, the shrinkage rate of the separation membrane increases, and the liquid absorption rate decreases, because the polyacrylonitrile fiber separation membrane has good high temperature resistance, and is not easy to shrink, melt and other phenomena; the flame retardant also contains hydroxyl groups, which can enhance the compatibility of the separation membrane with the electrolyte, so that it is quickly soaked by the electrolyte;

[0080] In the comparative example 3, the polyacrylonitrile fiber separator is replaced by the polypropylene separator, and the performance of the supercapacitor and the performance of the separator are all decreased. This is because the polyacrylonitrile fiber separator also has excellent mechanical properties and high voltage resistance, which endows the capacitor with good cycle stability. The hydroxyl group in the polyacrylonitrile fiber separator has strong polarity, enhances the compatibility of the separator and the electrolyte, makes the separator be quickly soaked by the electrolyte, reduces the interface resistance of ion migration, improves the ion conduction efficiency, and comprehensively improves the performance of the supercapacitor.

[0081] In the comparative example 4, the performance of the supercapacitor and the performance of the separator are more obviously decreased, which indicates that the setting of the materials and process conditions in the application can promote the performance improvement of the supercapacitor in the application at high temperature.

[0082] It is apparent for those skilled in the art that the application is not limited to the details of the above exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered as exemplary and non-limiting, and the scope of the application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the application.

Claims

1. A method for preparing a high-temperature resistant and highly stable supercapacitor, characterized in that: The method comprises the following steps: Step 1, the graphene, SuperP, polyimide acid solution, deionized water are mixed uniformly to obtain a slurry, the slurry is coated on aluminum foil and copper foil respectively, dried, and then imidized to obtain a positive electrode sheet and a negative electrode sheet respectively; Step 2, polyacrylonitrile powder and N,N-dimethylformamide are mixed, heated in a water bath, then a flame retardant is added and stirred uniformly to obtain a spinning solution, and the spinning solution is electrospun to obtain a polyacrylonitrile fiber diaphragm; Step 3, the positive electrode sheet, the polyacrylonitrile fiber diaphragm and the negative electrode sheet are laminated in sequence, and then wound to obtain an electric core, which is placed in a shell and injected with an electrolyte to obtain a super capacitor. In step 1, the polyimide acid solution is prepared by the following process: 2,3-diamino fluorobenzene, N-methyl pyrrolidone, diethylene triamine pentaacetic dianhydride are mixed, stirred and reacted under the protection of nitrogen atmosphere, then 1,1-bis(4-cyanophenoxy)ethane is added to obtain a polyimide acid solution.

2. The method according to claim 1, wherein the method is characterized by: In step 2, the flame retardant is prepared by the following process: S1: 2-amino-6-hydroxybenzothiazole, ethanol and 3-hydroxy-2-pyridine formaldehyde are mixed, heated and stirred to react, then cooled and dried to obtain an imine-containing compound; S2: DOPO and ethanol are mixed, ultrasonically treated, then the imine-containing compound is added, and oil bath heating and stirring are performed to react, and then cooled to obtain a flame retardant.

3. The method according to claim 2, wherein the method is characterized by: In S1, the ratio of 2-amino-6-hydroxybenzothiazole, ethanol and 3-hydroxy-2-pyridine formaldehyde is (1.0-1.5) g:10 mL:(1.0-1.4) g.

4. The method according to claim 2, wherein the method is characterized by: In S2, the ratio of DOPO, ethanol and the imine-containing compound is (8-12) g:100 mL:(10-14) g.

5. The method according to claim 1, wherein the method is characterized by: The mass ratio of 2,3-diamino fluorobenzene, N-methyl pyrrolidone, diethylene triamine pentaacetic dianhydride and 1,1-bis(4-cyanophenoxy)ethane is 10:(90-110):(12-16):(2.0-2.6).

6. The method according to claim 2, wherein the method is characterized by: In S1, the process conditions for heating and stirring are as follows: temperature 75-85℃, time 8-10h.

7. The method according to claim 2, wherein the method is characterized by: In S2, the process conditions for oil bath heating and stirring are as follows: temperature 80-85℃, time 10-12h, stirring speed 100-120r / min. 8.The method of claim 1, wherein the supercapacitor has high stability at high temperature. In step 1, the mass ratio of the graphene, SuperP, polyimide acid solution and deionized water is 10:(0.5-1.5):(1.5-2.5):(20-30); In step 2, the mass ratio of the polyacrylonitrile powder, N,N-dimethylformamide and the flame retardant is (1.0-1.4):10:(0.15-0.25).

9. A high temperature resistant and high stability supercapacitor, characterized in that: The preparation method according to any one of claims 1-8. The preparation method according to any one of claims 1-8.

Images