A supercapacitor

Abstract

This application discloses a supercapacitor, belonging to the field of supercapacitor fabrication technology. It includes a casing, within which a positive electrode, a negative electrode, a separator, an electrolyte, and a current collector are disposed. The positive and negative electrodes are arranged opposite each other, the separator is disposed between the positive and negative electrodes, the electrolyte is used to wet the positive and negative electrodes and the separator, and the current collector is used to conduct current to an external circuit. Both the positive and negative electrodes are made of a composite thin-film electrode material, which is prepared from a first separator formed by modified carbon nanotubes, a prepolymer solution obtained by polymerizing acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, and a pretreated aniline solution. The composite thin-film electrode material used in this supercapacitor exhibits enhanced interfacial bonding between the conductive polymer layer and the carbon-based material, which improves the cycle life of the positive and negative electrode materials, thereby enhancing the operational stability of the supercapacitor under extreme high-temperature environments.

Description

Technical Field

[0001] This application relates to a supercapacitor and belongs to the field of supercapacitor fabrication technology. Background Technology

[0002] Supercapacitors, also known as electrochemical capacitors, are a new type of energy storage device that lies between traditional electrostatic capacitors and chemical secondary batteries. Their basic structure consists of four core components: electrodes, electrolytes, separators, and current collectors. Their energy storage mechanism differs from the redox reaction of secondary batteries. Electrodes are the key to determining the capacity and power density of supercapacitors. Electrodes are mainly divided into two categories: double-layer capacitors and pseudocapacitors.

[0003] Among them, double-layer capacitors complete charge adsorption and storage through the double layer formed between the electrode material surface and the electrolyte interface. Commonly used electrode materials include carbon-based materials such as activated carbon, graphene, and carbon nanotubes. Pseudocapacitors, on the other hand, rely on rapid and reversible redox reactions that occur on the surface or in the bulk of the electrode material to achieve charge storage. Typical electrode materials include two-dimensional materials such as conductive polymers (e.g., polyaniline, polypyrrole), transition metal oxides (e.g., MnO2, RuO2), and MXenes.

[0004] Generally speaking, the advantage of double-layer capacitors is their high cycle life, while the disadvantages are their low specific capacitance and poor flexibility. Pseudocapacitors, on the other hand, exhibit obvious pseudocapacitive behavior, so the conductive polymers need to undergo additional treatment to improve their cycle stability.

[0005] To obtain flexible supercapacitors with high power density, energy density, and cycle stability, researchers have attempted to improve the electrochemical performance of flexible electrodes by modifying carbon-based materials with conductive polymers. For example, in his doctoral dissertation at Lanzhou University, "Preparation and Electrochemical Performance Study of Polyaniline-Modified Carbon-Based Flexible Self-Supporting Supercapacitor Electrode Materials," Liu Dong prepared a polyaniline / carbon-based composite flexible electrode using an in-situ polymerization method. Its specific capacitance can reach more than 800 F / g. However, this system still suffers from insufficient cycle stability and has not solved the problem of long-term performance degradation caused by the weak interfacial bonding between the polymer and the carbon-based material. For example, patent 202410428372.8 (IPC classification number H01G11 / 86) discloses a method for preparing a flexible self-supporting MXene-graphene-carbon nanotube thin film electrode material. It introduces graphene nanosheets and carbon nanotubes between the layers of MXene to obtain a self-supporting thin film electrode material. The introduction of graphene and carbon nanotubes suppresses the problem of easy stacking and oxidation of MXene and improves the electrochemical performance of the material. However, the electrochemical performance of the electrode material prepared by this method is greatly affected by temperature and it is difficult to maintain a high specific capacitance and rate performance at high temperatures. For example, patent 202210628690.X (IPC classification number H01G11 / 86) discloses a method for preparing a silver-coated flexible composite thin film electrode based on sodium polystyrene sulfonate-polyaniline. In this method, aniline and sodium polystyrene sulfonate form a complex, and then aniline is polymerized, impregnated with PVP, and then sprayed onto the surface to form a silver film. Although this method improves conductivity and stability, the preparation process is complex, and the PVP impregnation operation will cause phase separation of the sodium polystyrene sulfonate-polyaniline film, making it difficult to improve cycle performance.

[0006] Supercapacitors are increasingly being used in extreme high-temperature environments, such as electric vehicles, oil exploration, aerospace, and high-temperature furnaces. However, given the aforementioned issues, when supercapacitors made from carbon-based materials modified with this conductive polymer are used in extreme high-temperature environments, the delamination rate at the polymer-carbon interface accelerates, making it more difficult to maintain cycle stability.

[0007] Therefore, there is an urgent need for a supercapacitor that has a strong interface between polymer and carbon-based materials and is more suitable for stable operation at extreme high temperatures. Summary of the Invention

[0008] To address the aforementioned issues, a supercapacitor is provided in which the conductive polymer layer and carbon-based material in the composite thin-film electrode material used in the supercapacitor exhibit enhanced interfacial bonding, thereby improving the supercapacitor's cycle life and, in particular, enhancing its operational stability under extreme high-temperature environments.

[0009] This application provides a supercapacitor, which includes a housing, and a positive electrode, a negative electrode, a separator, an electrolyte, and a current collector are disposed inside the housing;

[0010] The positive and negative electrodes are arranged opposite to each other, the diaphragm is disposed between the positive and negative electrodes, the electrolyte is used to wet the positive electrode, the negative electrode and the diaphragm, and the current collector is used to conduct current to an external circuit;

[0011] Both the positive and negative electrodes are made of a composite thin-film electrode material, and the preparation method of the composite thin-film electrode material includes the following steps:

[0012] (1) Modified carbon nanotubes are added to MXene dispersion and graphene mixture, and after pulverization and stirring reaction, vacuum filtration, drying and annealing are performed to obtain the first film. The modified carbon nanotubes are carbon nanotubes with epoxy groups modified on the surface.

[0013] (2) Acrylamide, maleimide and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene were polymerized to obtain a prepolymer solution;

[0014] (3) Add the first film and the pretreated aniline solution to the prepolymer solution in step (2), add ammonium persulfate, react in an ice bath for at least 16 hours, then add dithiol compound and amine catalyst, heat to 50-60℃ and react for 4-6 hours, take out the first film, wash and dry it to obtain the composite thin film electrode material for supercapacitor.

[0015] The first improvement of this application regarding the composite thin-film electrode material is as follows: A prepolymer solution obtained by polymerizing acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene is used in step (3) with a pretreated aniline solution to grow a conductive polymer layer in situ on a first thin film, thus obtaining a novel composite thin-film electrode material. The conductive polymer layer is mainly composed of polyaniline, with a second polymer formed by prepolymerization as the main component. The introduction of this second polymer improves the temperature resistance of the conductive polymer layer, thereby extending its cycle stability.

[0016] Specifically, in step (3), ammonium persulfate is added for an ice bath reaction to form polyaniline. The subsequent addition of a dithiol compound and the resulting heating reaction causes the prepolymer to crosslink, forming a second polymer. This second polymer's crosslinked network can form an interpenetrating network with the polyaniline molecular chains, improving the bonding between the two polymers in the conductive polymer layer. This increases the density of the conductive polymer layer and eliminates microscopic interface separation, thereby simultaneously improving the temperature resistance and chemical stability of the conductive polymer layer. Furthermore, due to the existence of this interpenetrating crosslinked network, it does not affect the conductivity of the polyaniline itself; therefore, this improvement maintains the original electrical properties of the conductive polymer layer.

[0017] The second improvement of the composite thin film electrode material in this application is as follows: a first thin film is formed by using MXene dispersion with graphene and modified carbon nanotubes. MXene has high conductivity and can form a good interfacial interaction with carbon nanotubes, which improves the electron transport efficiency of the first thin film and thus improves the conductivity. It can also provide support for the first thin film, which facilitates the in-situ polymerization of prepolymer and polyaniline on the surface of the first thin film.

[0018] Specifically, the preparation method of MXene dispersion is as follows:

[0019] After mixing and stirring HCl and deionized water, LiF was added, and hydrofluoric acid solution was prepared by magnetic stirring. Ti3AlC2 was added to the hydrofluoric acid solution and magnetically stirred. The liquid was centrifuged and washed until neutral, and then sonicated and centrifuged several times. The supernatant was taken to obtain MXene dispersion.

[0020] The third improvement of this application for composite thin film electrode materials is as follows: a first thin film is formed by using carbon nanotubes with epoxy groups modified on the surface. This improvement enables the first thin film to have epoxy groups. In the process of forming polyaniline and the second polymer in step (3), the epoxy groups on the modified carbon nanotubes can undergo ring-opening reactions with the amino groups on the polyaniline molecular chain and the amino groups (acrylamide, maleimide) carried by the second polymer to achieve chemical bonding between the carbon-based material and the conductive polymer layer, thereby improving the interfacial bonding force between the conductive polymer and the carbon-based material. This can significantly improve the cycle stability of the composite thin film electrode material and reduce the performance degradation of the composite thin film electrode material.

[0021] With the above improvements, the interfacial bonding force between the carbon-based material and the conductive polymer layer is enhanced, which suppresses the interfacial delamination of the composite thin film electrode material when it is running at extreme high temperatures. This improves the operational stability of the composite thin film electrode material at high temperatures and broadens the application prospects of supercapacitors in extreme high-temperature environments.

[0022] Optionally, in step (2), the molar ratio of acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene is 1:(0.4-0.7):(0.2-0.4).

[0023] The proportions of the three compounds in the prepolymer facilitate the formation of the cross-linked network of the second polymer, enabling a synergistic improvement in conductivity, temperature resistance, and adhesion to carbon-based materials. Excessive acrylamide or maleimide results in overly long molecular chains between adjacent cross-linking points of the second polymer, affecting the density of the conductive polymer layer and thus reducing electrical performance. Conversely, insufficient acrylamide or maleimide reduces the number of binding sites with the carbon-based material, decreasing the interfacial bonding between the conductive polymer layer and the carbon-based material, thereby decreasing the cycle stability of the composite thin-film electrode material. Furthermore, insufficient maleimide also reduces the temperature resistance of the second polymer, similarly leading to decreased cycle stability of the composite thin-film electrode material.

[0024] 1,4-Bis-[4-(6-Acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene plays a role in crosslinking and improving temperature resistance in the second polymer. If too much of it is added, the number of crosslinking points in the second polymer increases, which reduces the flexibility and toughness of the conductive polymer layer, making the conductive polymer layer prone to cracking and reducing its service life. If too little is added, it will reduce the temperature resistance of the conductive polymer layer and will not be able to form a good crosslinking network. The interpenetration bonding with the polyaniline molecular chain will decrease, resulting in microscopic interface separation in the conductive polymer layer and reducing the chemical stability of the conductive polymer layer.

[0025] The molar ratio of acrylamide to aniline in the pretreated aniline solution is 1:(6-8).

[0026] The conductive polymer layer is mainly composed of polyaniline and supplemented by a second polymer. Under this limitation, the electrochemical performance of the conductive polymer layer can be maintained, so that the composite thin film electrode material has high power density and energy density. At the same time, the temperature resistance of the conductive polymer layer can be improved, and the bonding force between the conductive polymer layer and the first film can be improved, which significantly improves the cycle stability of the composite thin film electrode material.

[0027] Optionally, the specific operation for obtaining the prepolymer in step (2) is as follows:

[0028] Acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene were added to a solvent. After adding a thermal initiator and a photoinitiator, the temperature was raised to 60-80℃ and irradiated with ultraviolet light for 1-2 hours to obtain a prepolymer solution.

[0029] The preparation of this prepolymer uses thermal and photoinitiators to initiate the reaction, which can improve the reactivity of the reactants and ensure that the reactants quickly prepolymerize to form prepolymer molecular chains. At this reaction time, the three reactants only achieve preliminary polymerization, and the resulting prepolymer molecular chains are relatively short and have not formed a cross-linked network, which can ensure that the molecular chains interpenetrate with the molecular chains of polyaniline in step (3). In addition, the prepolymer solution also contains some unreacted reactants, which can react again after heating in step (3) to form a second polymer cross-linked network.

[0030] The thermal initiator is selected from azobisisobutyronitrile, and the photoinitiator is selected from benzoyl dimethyl ether.

[0031] The amount of thermal initiator added is 0.5wt%-2wt% of the total weight of the reactants.

[0032] Optionally, in step (3), the molar ratio of aniline to ammonium persulfate in the aniline solution is 1:(0.3-0.5).

[0033] Optionally, in step (3), the molar ratio of the dithiol compound to acrylamide is (0.1-0.2):1.

[0034] The dithiol compound added in step (3) can react with the double bonds in the prepolymer solution to adjust the degree of crosslinking of the second polymer, so that it can better bind with polyaniline.

[0035] Optionally, the dithiol compound in step (3) is selected from at least one of ethylenedithiol, propylenedithiol, butanedithiol, pyridine-2,6-dithiol, and 2,2'-(1,2-ethylenedioxy)diethylthiol.

[0036] Optionally, the amount of amine catalyst added is 5 wt% to 8 wt% of 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene.

[0037] Optionally, the method for preparing the pretreated aniline solution in step (3) is as follows:

[0038] Aniline is added to hydrochloric acid solution, mixed thoroughly, and allowed to stand. After the solution separates into layers, the lower layer is taken out, which is the pretreated aniline solution.

[0039] Optionally, the amine catalyst in step (3) is selected from at least one of dipropylamine, triethylamine, and pyridine.

[0040] Optionally, the modified carbon nanotubes are prepared by:

[0041] Aminated carbon nanotubes are completely immersed in a solution of a diepoxide compound, ultrasonically dispersed for at least 30 minutes, and then filtered, washed, and dried to obtain the final product.

[0042] Optionally, the concentration of the solution of the diepoxide compound is 10-20 wt%.

[0043] The temperature for ultrasonic dispersion is 30-50℃.

[0044] Optionally, the biepoxide compound includes at least one of diepoxide glycerol ether (CAS: 2238-07-5), ethylene glycol diglycidyl ether (CAS: 2224-15-9), 1,4-butanediol diglycidyl ether (CAS: 2425-79-8), 1,6-hexanediol diglycidyl ether (CAS: 16096-31-4), and tetraethylene glycol diglycidyl ether (CAS: 17626-93-6).

[0045] When aminated carbon nanotubes are placed in a solution of a diepoxy compound, the amino groups on the surface of the carbon nanotubes can undergo a ring-opening reaction with one of the epoxy groups in the diepoxy compound, allowing the diepoxy compound to be grafted onto the surface of the carbon nanotubes. Due to the molecular structure of the diepoxy compound, after one epoxy group has undergone a ring-opening reaction with the amino group on the surface of the aminated carbon nanotube, the other epoxy group is limited by steric hindrance and molecular chain length and cannot react with the remaining amino groups on the surface of the carbon nanotube. Therefore, the modified carbon nanotubes can have epoxy groups on their surface, which can then participate in the chemical reaction with the conductive polymer layer to form a chemical connection between the conductive polymer layer and the first film.

[0046] Optionally, the modified carbon nanotubes are prepared by:

[0047] Aminated carbon nanotubes were completely immersed in a solution of a diepoxide compound, ultrasonically dispersed for at least 30 minutes, and then filtered, washed, and dried to obtain an intermediate.

[0048] The intermediate is completely immersed in a solution of an amino-containing alkene compound with a concentration of 10wt%-15wt%, and then ultrasonically dispersed for at least 30 minutes. After filtration, washing, and drying, the intermediate is obtained. The molar ratio of the amino-containing alkene compound to the diepoxide compound is (0.3-0.5):1.

[0049] In this scheme, the carbon nanotubes modified with biepoxides undergo a reaction with amino-containing olefins. Some of the epoxy groups on the surface of the biepoxide-modified carbon nanotubes undergo a ring-opening reaction with the amino groups of the amino-containing olefins, resulting in double bonds on the surface of the carbon nanotubes. These double bonds can react with one end of the thiol in the dithiol compound to achieve chemical bonding between the carbon nanotubes and the second polymer, further improving the bonding between the conductive polymer layer and the carbon-based material.

[0050] The molar ratio of amino-containing olefins to biepoxides is (0.3-0.5):1. Under this setting, at least half of the epoxy groups modified on the surface of carbon nanotubes remain, and they can still participate in the ring-opening of amino groups in the second polymer and polyaniline to achieve the original chemical connection.

[0051] After modification with alkene compounds containing amino groups, regardless of whether the carbon nanotube surface has epoxy groups or double bonds, although the total number of sites that can chemically react with the conductive polymer layer remains unchanged, the actual number of sites participating in the reaction is less than the total number of sites that can participate in the reaction. This is because, due to the influence of steric hindrance and molecular chain length, it is difficult to achieve the participation of all epoxy groups and double bonds on the carbon nanotube surface in the reaction.

[0052] Based on the ring-opening reaction characteristics of epoxy groups and amino groups, and the reaction characteristics of thiols and double bonds, this application demonstrates that the bonding force between carbon nanotubes modified with amino-containing alkene compounds and the conductive polymer layer is enhanced. This proves that the modification operation increases the total number of reaction sites on the surface of carbon nanotubes, which can further improve the cycle stability of the composite thin film electrode material.

[0053] Optionally, the amino-containing olefin compound includes at least one of 4-vinylaniline (CAS: 1520-21-4), 2-vinylmorpholine, N-methylallylamine (CAS: 627-37-2), and N-ethylmethylpropenylamine (CAS: 18328-90-0).

[0054] Preferably, the amino-containing alkene compound is selected from 4-vinylaniline and N-methylallylamine in a molar ratio of 1:3.

[0055] This configuration can further improve the interfacial bonding between the conductive polymer layer and the carbon-based material, and improve the conductivity of the composite thin film electrode material.

[0056] Optionally, the weight ratio of Mxene, graphene, and modified carbon nanotubes is 6:(2-3):1.

[0057] Optionally, the annealing in step (1) is: heating to 400-600℃ at a rate of 2-5℃ / min and holding for 1h under an inert atmosphere.

[0058] Optionally, the drying in step (1) is freeze drying at a temperature of -40°C for 24-36 hours.

[0059] Optionally, the electrolyte is selected from any one of aqueous electrolytes, organic electrolytes, or solid gel electrolytes;

[0060] The diaphragm is a porous polymer film or a cellulose membrane.

[0061] Optionally, the aqueous electrolyte is an aqueous solution of sulfuric acid, an aqueous solution of potassium hydroxide, or an aqueous solution of sodium sulfate; the organic electrolyte is a mixed system of tetraethylammonium tetrafluoroborate or tetraethylammonium hexafluorophosphate dissolved in propylene carbonate and acetonitrile; and the solid gel electrolyte is a PVA-KOH gel electrolyte.

[0062] Optionally, the porous polymer film is a polypropylene microporous membrane or a polyethylene microporous membrane.

[0063] The beneficial effects of this application include, but are not limited to:

[0064] 1. According to the supercapacitor of this application, polyaniline is used as a conductive polymer layer in the composite thin film electrode material. The prepolymer can form a cross-linked network in the polyaniline layer to improve the temperature resistance of the conductive polymer layer and extend the service life of the composite thin film electrode material at high temperatures.

[0065] 2. According to the supercapacitor of this application, the composite thin film electrode material uses carbon nanotubes with epoxy groups on the surface. The epoxy groups can undergo ring-opening reaction with the amino groups on the polyaniline chain and the amino groups carried in acrylamide and maleimide in step (3) to form chemical crosslinks, so as to realize the chemical bonding between the conductive polymer layer and the carbon-based material and improve the interfacial bonding force between the conductive polymer layer and the carbon-based material in the composite thin film electrode material.

[0066] 3. According to the supercapacitor of this application, the prepolymer in the composite thin film electrode material is reacted and crosslinked to form a second polymer after the aniline is polymerized. This allows the crosslinked network formed by the second polymer to interpenetrate with the molecular chains of polyaniline, thereby improving the bonding between the crosslinked network of the second polymer and polyaniline, and thus improving the density, temperature resistance and chemical stability of the conductive polymer layer.

[0067] 4. According to the supercapacitor of this application, the composite thin film electrode material can significantly improve its cycle stability while maintaining the electrical performance of the positive and negative electrodes, especially the operational stability of the capacitor at extreme high temperatures, thereby broadening the application prospects of supercapacitors in extreme high-temperature environments. Attached Figure Description

[0068] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0069] Figure 1 This is a GCD specific capacitance test diagram of the composite thin film electrode material involved in Embodiment 1 of this application;

[0070] Figure 2This is a graph showing the energy density of the composite thin-film electrode material involved in Embodiment 1 of this application.

[0071] Figure 3 This is a cycle performance test diagram of the composite thin film electrode material involved in Embodiment 1 of this application;

[0072] Figure 4 This is a characterization graph of the rate of performance degradation of the composite thin film electrode material involved in Example 1 of this application after 1000 bending cycles;

[0073] Figure 5 This is a characterization graph showing the rate of performance degradation of the composite thin film electrode material involved in Example 1 of this application after being placed at 80°C for 30 days. Detailed Implementation

[0074] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0075] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0076] Unless otherwise specified, the methods used in the embodiments of this application are conventional methods in the prior art.

[0077] The preparation method of the MXene dispersion in Example 1 below is as follows:

[0078] Hydrofluoric acid was prepared by mixing HCl and deionized water at a volume ratio of 3:1 and stirring for 5 min, then adding LiF and magnetically stirring at 35℃ for 30 min. Ti3AlC2 at a weight ratio of 1:1 was added and magnetically stirred at 35℃ for 26 h. The mixture was then centrifuged and washed at 3500 r / min until neutral. The mixture was then sonicated and centrifuged again. The supernatant was collected to obtain the MXene dispersion.

[0079] The preparation method of the graphene mixture in Example 1 below is as follows:

[0080] Graphite foil was used as the carbon electrode, i.e., the anode, and platinum wire was used as the cathode for electrochemical exfoliation of graphite. The graphite foil and platinum electrode were placed in a 0.1M MgSO4 solution, and electrochemical exfoliation was performed by applying a positive voltage of 10V to the graphite electrode. After the graphite was exfoliated, the product was vacuum filtered with deionized water to obtain exfoliated graphene. The exfoliated graphene was dispersed in deionized water, sonicated for 20 min, and then centrifuged at 3000 r / min for 20 min to form a graphene dispersion with a concentration of 5 mg / ml.

[0081] The method for preparing the pretreated aniline solution in Example 1 below is as follows:

[0082] Add aniline monomer to 0.5 mol / L hydrochloric acid. The mass-to-volume ratio of aniline to hydrochloric acid is 1:2 (g / ml). After thorough mixing, let stand for 2 hours. After the solution separates into layers, take the lower layer.

[0083] Example 1

[0084] This embodiment relates to a method for preparing a composite thin-film electrode material for supercapacitors, including the following steps:

[0085] (1) Modified carbon nanotubes were added to MXene dispersion and graphene mixture, and after pulverization and stirring reaction, the first film was obtained by vacuum filtration, drying and annealing. The modified carbon nanotubes were carbon nanotubes with epoxy groups modified on the surface.

[0086] (2) Acrylamide, maleimide and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene were polymerized to obtain a prepolymer solution;

[0087] (3) Add the first film and the pretreated aniline solution to the prepolymer solution in step (2), add ammonium persulfate, react in an ice bath for at least 16 hours, then add dithiol compound and amine catalyst, heat to 50-60℃ and react for 4-6 hours, take out the first film, wash and dry it to obtain the final product.

[0088] In one embodiment, in step (2), the molar ratio of acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene is 1:(0.4-0.7):(0.2-0.4).

[0089] Specifically, the molar ratio of acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene can be 1:0.4:0.2, 1:0:5:0.2, 1:0.6:0.2, 1:0.7:0.2, 1:0.4:0.3, 1:0:5:0.3, 1:0.6:0.3, 1:0.7:0.3, 1:0.4:0.4, 1:0:5:0.4, 1:0.6:0.4, 1:0.7:0.4, or any ratio between these ratios.

[0090] As one implementation method, the molar ratio of acrylamide to aniline in the pretreated aniline solution is 1:(6-8).

[0091] Specifically, the molar ratio of acrylamide in the prepolymer solution to aniline in the pretreated aniline solution can be 1:6, 1:7, 1:8, or any ratio in between.

[0092] As one implementation method, the specific operation for obtaining the prepolymer in step (2) is as follows:

[0093] Acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene were added to a solvent. After adding a thermal initiator and a photoinitiator, the temperature was raised to 60-80℃ and irradiated with ultraviolet light for 1-2 hours to obtain a prepolymer solution.

[0094] Specifically, the heating temperature can be any temperature between 60℃, 65℃, 70℃, 75℃, and 80℃, and the reaction time can be any time between 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, and 2h.

[0095] In one embodiment, in step (3), the molar ratio of aniline to ammonium persulfate in the aniline solution is 1:(0.3-0.5).

[0096] Specifically, the molar ratio of aniline to ammonium persulfate in the aniline solution can be 1:0.3, 1:0.4, 1:0.5, or any ratio in between.

[0097] In one implementation, the molar ratio of dithiol compound to acrylamide in step (3) is (0.1-0.2):1.

[0098] Specifically, the molar ratio of thiol compound to acrylamide can be 0.1:1, 0.2:1, or any ratio of the stent.

[0099] As one implementation, the dithiol compound in step (3) is selected from at least one of ethylenedithiol, propylenedithiol, butanedithiol, pyridine-2,6-dithiol, and 2,2'-(1,2-ethylenedioxy)diethylthiol.

[0100] As one implementation method, the modified carbon nanotubes are prepared as follows:

[0101] Aminated carbon nanotubes are completely immersed in a solution of a diepoxide compound, ultrasonically dispersed for at least 30 minutes, and then filtered, washed, and dried to obtain the final product.

[0102] In one implementation method, the concentration of the diepoxide solution is 10-20 wt%; the ultrasonic dispersion temperature is 30-50°C.

[0103] Specifically, the concentration of the biepoxide solution refers to the mass ratio of the biepoxide to the total solution. This concentration can be 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, or any concentration between these values.

[0104] Specifically, the ultrasonic dispersion temperature can be 30℃, 35℃, 40℃, 45℃, 50℃, or any temperature in between.

[0105] Based on the parameters defined above, the following materials and comparative materials were prepared, as detailed below:

[0106] Material 1#

[0107] Includes the following steps:

[0108] (1) Modified carbon nanotubes were added to the MXene dispersion and graphene mixture, ultrasonically pulverized at 280W for 20 min, magnetically stirred for 5 h, and then the mixture was vacuum filtered to form a film. After freeze-drying at -40℃ for 24 h, the film was then heated to 600℃ at 2℃ / min and held for 1 h under an argon atmosphere to obtain the first film. The weight ratio of MXene, graphene, and modified carbon nanotubes was 6:3:1. The preparation method of modified carbon nanotubes was as follows:

[0109] Aminated carbon nanotubes were completely immersed in an aqueous solution of 10 wt% diglycidyl ether, ultrasonically dispersed at 50 °C for 30 min, filtered, washed three times with deionized water, and dried at 50 °C for 12 h to obtain the product.

[0110] (2) Acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene in a molar ratio of 1:0.4:0.4 were added to a solvent. Then, 0.5 wt% of thermal initiator azobisisobutyronitrile and 2 wt% of photoinitiator benzoyl dimethyl ether were added to the total reactants. The temperature was raised to 80°C and irradiated with ultraviolet light for 1 h to obtain a prepolymer solution.

[0111] (3) Add the first film and the pretreated aniline solution to the prepolymer solution in step (2), add ammonium persulfate, the molar ratio of acrylamide to aniline in the pretreated aniline solution is 1:6, the molar ratio of aniline to ammonium persulfate is 1:0.3, react in an ice bath for 16 h, then add ethylenedithiol and dipropylamine, the molar ratio of ethylenedithiol to acrylamide is 0.1:1, the amount of dipropylamine added is 5 wt% of 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, heat to 60℃ and react for 4 h, take out the first film, wash it 3 times with a mixed solution of deionized water and ethanol (volume ratio of deionized water and ethanol is 1:1), dry at 50℃ for 24 h, and obtain the composite thin film electrode material for supercapacitors.

[0112] Material 2#

[0113] Includes the following steps:

[0114] (1) Modified carbon nanotubes were added to the MXene dispersion and graphene mixture, ultrasonically pulverized at 280W for 20 min, magnetically stirred for 5 h, and then the mixture was vacuum filtered to form a film. After freeze-drying at -40℃ for 36 h, the film was then heated to 400℃ at 5℃ / min and held for 1 h under an argon atmosphere to obtain the first film. The weight ratio of MXene, graphene, and modified carbon nanotubes was 6:2:1. The preparation method of modified carbon nanotubes was as follows:

[0115] Aminated carbon nanotubes were completely immersed in an ethanol solution of 20 wt% ethylene glycol diglycidyl ether, ultrasonically dispersed at 30 °C for 60 min, filtered, washed three times with ethanol, and dried at 50 °C for 12 h to obtain the product.

[0116] (2) Acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene in a molar ratio of 1:0.7:0.2 were added to a solvent. Then, 2 wt% of the thermal initiator azobisisobutyronitrile and 0.5 wt% of the photoinitiator benzoyl dimethyl ether were added. The temperature was raised to 60°C and irradiated with ultraviolet light for 2 h to obtain a prepolymer solution.

[0117] (3) Add the first film and the pretreated aniline solution to the prepolymer solution in step (2), add ammonium persulfate, the molar ratio of acrylamide to aniline in the pretreated aniline solution is 1:8, the molar ratio of aniline to ammonium persulfate is 1:0.5, react in an ice bath for 20 h, then add propylene glycol and triethylamine, the molar ratio of propylene glycol to acrylamide is 0.2:1, the amount of triethylamine added is 8 wt% of 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, heat to 50 °C and react for 6 h, take out the first film, wash it 3 times with a mixed solution of deionized water and ethanol (volume ratio of deionized water and ethanol is 1:1), dry at 50 °C for 24 h, and obtain the composite thin film electrode material for supercapacitors.

[0118] Material 3#

[0119] The difference between this material and material #2 is that the molar ratio of acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene is 1:0.7:0.1.

[0120] Material 4#

[0121] The difference between this material and material #2 is that the molar ratio of acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene is 1:0.7:0.5.

[0122] Material 5#

[0123] The difference between this material and material 2# is that the molar ratio of acrylamide to aniline in the pretreated aniline solution is 1:5.

[0124] Material 6#

[0125] The difference between this material and material 2# is that the molar ratio of dithiol compound to acrylamide in step (3) is 0.05:1.

[0126] Material 7#

[0127] The difference between this material and material 2 is that the concentration of the ethanol solution of ethylene glycol diglycidyl ether is 5wt%.

[0128] Material #8

[0129] The difference between this material and Material 2# is that the preparation method of the modified carbon nanotubes is as follows:

[0130] Aminated carbon nanotubes were completely immersed in an ethanol solution of 20 wt% ethylene glycol diglycidyl ether, ultrasonically dispersed at 30 °C for 60 min, filtered, washed three times with ethanol, and dried at 50 °C for 12 h to obtain the intermediate.

[0131] The intermediate was completely immersed in a chloroform solution of N-ethylmethylpropenylamine at a concentration of 15 wt%, and then ultrasonically dispersed again at 30 °C for 60 min. After filtration, it was washed three times with chloroform and once with ethanol, and then dried at 50 °C for 12 h to obtain the product. The molar ratio of N-ethylmethylpropenylamine to diethylene glycol diglycidyl ether was 0.5:1.

[0132] Material 9#

[0133] The difference between this material and Material 2# is that the preparation method of the modified carbon nanotubes is as follows:

[0134] Aminated carbon nanotubes were completely immersed in an ethanol solution of 20 wt% ethylene glycol diglycidyl ether, ultrasonically dispersed at 30 °C for 60 min, filtered, washed three times with ethanol, and dried at 50 °C for 12 h to obtain the intermediate.

[0135] The intermediate was completely immersed in an ethanol solution of 10 wt% 4-ethyleneaniline, and then ultrasonically dispersed again at 30 °C for 60 min. After filtration and washing with ethanol three times, it was dried at 50 °C for 12 h to obtain the product. The molar ratio of 4-ethyleneaniline to diethylene glycol diglycidyl ether was 0.3:1.

[0136] Material 10#

[0137] The difference between this material and material 9# is that 4-vinylaniline and N-methylallylamine in a molar ratio of 1:3 are used to replace 4-vinylaniline. The intermediate is completely impregnated in an ethanol-water mixed solution of 4-vinylaniline and N-methylallylamine in a molar ratio of 1:3 (volume ratio of ethanol to water is 1:1). The concentrations of 4-vinylaniline and N-methylallylamine are both 10 wt%.

[0138] Comparative material D1#

[0139] The difference between this comparative material and material 2 is that it uses unmodified carbon nanotubes.

[0140] Comparison material D2#

[0141] The difference between this comparative material and material 2 is that MXene dispersion is not added, and the MXene dispersion is replaced with an equal volume of graphene mixture.

[0142] Comparison material D3#

[0143] The difference between this comparative material and material 2# is that sodium styrene sulfonate is used instead of 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene.

[0144] Comparison material D4#

[0145] The difference between this comparative material and material 2 is that acrylic acid is used instead of acrylamide.

[0146] Comparison material D5#

[0147] The difference between this comparative material and material 2# is that maleimide is not added.

[0148] Comparative material D6#

[0149] The difference between this comparative material and material 2# is that it does not contain propylene dithiol and triethylamine.

[0150] Comparative material D7#

[0151] The difference between this comparative material and material 9# is that it does not contain propylene dithiol and triethylamine.

[0152] Comparison material D8#

[0153] Includes the following steps:

[0154] Step (1) is the same as for material #2;

[0155] (2) The first film was added to the pretreated aniline solution, ammonium persulfate was added, and the reaction was carried out in an ice bath for 20 h. The molar ratio of acrylamide to aniline in the pretreated aniline solution was 1:8, and the molar ratio of aniline to ammonium persulfate was 1:0.5.

[0156] (3) Acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene in a molar ratio of 1:0.7:0.2 were added to a solvent, and 2 wt% of azobisisobutyronitrile (a thermal initiator) and 0.5 wt% of benzoyl dimethyl ether (a photoinitiator) were added to obtain a reaction solution. The reaction solution was added to the solution obtained in step (2), the temperature was raised to 60°C, and the reaction was irradiated with ultraviolet light to polymerize the reaction. h, then propylene dithiol and triethylamine are added, with a molar ratio of propylene dithiol to acrylamide of 0.2:1 and an amount of triethylamine added of 8 wt% of 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene. The temperature is raised to 50℃ and reacted for 6 h. The first film is taken out and washed three times with a mixed solution of deionized water and ethanol (volume ratio of deionized water and ethanol of 1:1). It is then dried at 50℃ for 24 h to obtain the composite thin film electrode material for supercapacitors.

[0157] Comparison material D9#

[0158] Includes the following steps:

[0159] Step (1) is the same as for material #2;

[0160] (2) The first film was added to the pretreated aniline solution, and ammonium persulfate was added. The reaction was carried out in an ice bath for 20 hours. The molar ratio of acrylamide to aniline in the pretreated aniline solution was 1:8, and the molar ratio of aniline to ammonium persulfate was 1:0.5. The first film was taken out and washed three times with a mixed solution of deionized water and ethanol (volume ratio of deionized water and ethanol was 1:1). It was dried at 50°C for 24 hours to obtain the composite thin film electrode material for supercapacitors.

[0161] Test Example 1

[0162] The electrochemical performance of each composite thin-film electrode material obtained in Example 1 was tested, and the test results are shown in Table 1. Figure 1 , Figure 2 , Figure 3 As shown, the test method refers to the doctoral dissertation of Lanzhou University, "Preparation and Electrochemical Performance Study of Carbon-based Flexible Self-supporting Supercapacitor Electrode Material Modified by Polyaniline". The test current density of the GCD (galvanostatic charge-discharge curve) specific capacitance value in Table 1 is 1A / g. All test values ​​in Table 1 are obtained at room temperature.

[0163] The retention rate of specific capacitance after 2000 CV (cyclic voltammetry) cycles = (specific capacitance after 2000 CV cycles / initial specific capacitance) × 100%.

[0164] The ratio of the material's specific capacitance value at the highest current density to that at the lowest current density = (specific capacitance value obtained from GCD test at a current density of 10 A / g / specific capacitance value obtained from GCD test at a current density of 1 A / g) × 100%. This test result refers to the test result at room temperature.

[0165] Table 1. Initial electrochemical performance test results of each material in Example 1

[0166]

[0167] Test Example 2

[0168] The electrochemical performance of each composite thin-film electrode material prepared in Example 1 was tested at room temperature after 1000 repeated bending cycles. The decrease rate of specific capacitance retention after 2000 CV cycles after bending (C1) and the decrease rate of the ratio of specific capacitance at the highest and lowest current densities after bending (G1) were calculated. The test results are shown in Table 2 and [Table data would be inserted here]. Figure 4 .

[0169] Simultaneously, the composite thin-film electrode material was placed at 80℃ for 30 days, and then its electrochemical performance was tested at 80℃. The decrease rate of specific capacitance retention after 2000 CV cycles after high-temperature treatment at 80℃ (C2) and the decrease rate of the ratio of the material's specific capacitance at the highest and lowest current densities after high-temperature treatment at 80℃ (G2) were calculated. The test results are shown in Table 2 and... Figure 5 .

[0170] The methods for testing the specific capacitance retention rate after 2000 CV cycles and the specific capacitance of the material at the highest and lowest current densities in Table 2 are the same as those in Test Example 1.

[0171] The decrease rate of specific capacitance retention after 2000 CV cycles after bending (C1) = [(W1-W2) / W2]×100%, where W1 is the specific capacitance retention rate of the composite thin film electrode material after 2000 CV cycles at room temperature before bending, and W2 is the specific capacitance retention rate of the composite thin film electrode material after 2000 CV cycles at room temperature after bending 1000 times.

[0172] The ratio of the decrease in the specific capacitance of the material at the highest and lowest current densities after bending (G1) = [(W3-W4) / W3]×100%, where W3 is the specific capacitance of the composite thin film electrode material at the highest and lowest current densities tested at room temperature before bending, and W4 is the specific capacitance of the composite thin film electrode material at the highest and lowest current densities tested at room temperature after bending 1000 times.

[0173] The decrease rate of specific capacitance retention after 2000 CV cycles after high temperature treatment (C2) = [(W5-W6) / W2]×100%, where W5 is the specific capacitance retention rate of the composite thin film electrode material after 2000 CV cycles at room temperature before high temperature treatment at 80℃, and W6 is the specific capacitance retention rate of the composite thin film electrode material after 2000 CV cycles at 80℃ after high temperature treatment at 80℃.

[0174] The ratio of the decrease in the specific capacitance of the material at the highest and lowest current densities after high temperature treatment (G2) = [(W7-W8) / W7]×100%, where W7 is the specific capacitance of the composite thin film electrode material at the highest and lowest current densities tested at room temperature before the 80℃ high temperature treatment, and W8 is the specific capacitance of the composite thin film electrode material at the highest and lowest current densities tested at 80℃ after the 80℃ high temperature treatment.

[0175] Table 2. Electrochemical stability test results of various materials in Example 1

[0176]

[0177] According to Table 1 above, Figure 1-3 The data shows that the specific capacitance of the composite thin film electrode material of this application is above 900 F / g, the specific capacitance retention rate after 2000 CV cycles is above 94.9%, and the ratio of the specific capacitance of the material at the highest current density to the lowest current density is above 79.4%, which proves that the composite thin film electrode material has excellent electrochemical performance and electrochemical stability.

[0178] According to Table 2, Figure 4 , Figure 5 The data shows that after being bent 1000 times and treated at 80°C, the composite thin film electrode material of this application exhibits a smaller rate of decrease in the retention rate of specific capacitance after CV cycles compared to the rate of decrease in the ratio of the specific capacitance value at the highest and lowest current densities. This demonstrates that the composite thin film electrode material can be used in flexible self-supporting supercapacitors and exhibits excellent cycle stability at high temperatures, thus broadening the application prospects of supercapacitors prepared from composite thin film electrode materials in high-temperature fields.

[0179] Example 2

[0180] This embodiment relates to a supercapacitor, which includes a housing, and a positive electrode, a negative electrode, a diaphragm, an electrolyte, and a current collector are disposed inside the housing;

[0181] The positive and negative electrodes are arranged opposite each other, the diaphragm is placed between the positive and negative electrodes, the electrolyte is used to wet the positive electrode, the negative electrode and the diaphragm, and the current collector is used to conduct the current to the external circuit.

[0182] The positive and negative electrodes are made of any one of the composite thin film electrode materials 1#-10# in Example 1.

[0183] In one embodiment, the electrolyte is selected from any one of aqueous electrolytes, organic electrolytes, or solid gel electrolytes; the diaphragm is a porous polymer membrane or a cellulose membrane.

[0184] In one embodiment, the aqueous electrolyte is an aqueous solution of sulfuric acid, potassium hydroxide, or sodium sulfate; the organic electrolyte is a mixture of tetraethylammonium tetrafluoroborate or tetraethylammonium hexafluorophosphate dissolved in propylene carbonate and acetonitrile; and the solid gel electrolyte is a PVA-KOH gel electrolyte.

[0185] In one embodiment, the porous polymer film is a polypropylene microporous membrane or a polyethylene microporous membrane.

[0186] The positive and negative electrodes of the supercapacitor in this embodiment are made of any one of the composite thin-film electrode materials 1#-10# from Example 1. The electrochemical performance of the composite thin-film electrode material in this supercapacitor is shown in Tables 1 and 2. The supercapacitor of this embodiment was operated stably at 80°C for three months, and the specific capacitance retention rate was above 80%.

[0187] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A supercapacitor, characterized in that, It includes a housing, within which a positive electrode, a negative electrode, a diaphragm, an electrolyte, and a current collector are disposed; The positive and negative electrodes are arranged opposite to each other, the diaphragm is disposed between the positive and negative electrodes, the electrolyte is used to wet the positive electrode, the negative electrode and the diaphragm, and the current collector is used to conduct current to an external circuit; Both the positive and negative electrodes are made of a composite thin-film electrode material, and the preparation method of the composite thin-film electrode material includes the following steps: (1) Modified carbon nanotubes are added to an MXene dispersion and a graphene mixture. After ultrasonic pulverization and magnetic stirring, the mixture is vacuum filtered, dried, and annealed to obtain a first film. The modified carbon nanotubes are carbon nanotubes with epoxy groups modified on their surface. The preparation method of the modified carbon nanotubes is as follows: Aminated carbon nanotubes are completely impregnated in a solution of a diepoxide compound, ultrasonically dispersed for at least 30 minutes, filtered, washed, and dried to obtain the product. The concentration of the diepoxide compound solution is 10-20 wt%. (2) Acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene are polymerized to obtain a prepolymer solution, wherein the molar ratio of acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene is 1:(0.4-0.7):(0.2-0.4); (3) Add the first film and the pretreated aniline solution to the prepolymer solution of step (2), add ammonium persulfate, react in an ice bath for at least 16 hours, then add a dithiol compound and an amine catalyst, heat to 50-60℃ and react for 4-6 hours, take out the first film, wash and dry it to obtain the product. The dithiol compound is selected from at least one of ethylenedithiol, propylenedithiol, butanedithiol, pyridine-2,6-dithiol, and 2,2'-(1,2-ethylenedioxy)diethylthiol, and the amine catalyst is selected from at least one of dipropylamine, triethylamine, and pyridine. The specific steps for obtaining the prepolymer in step (2) are as follows: Acrylamide, maleimide, and 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene were added to a solvent. After adding a thermal initiator and a photoinitiator, the temperature was raised to 60-80℃ and irradiated with ultraviolet light for 1-2 hours to obtain a prepolymer solution. The preparation method of the graphene mixture is as follows: Graphite foil was used as the carbon electrode, i.e., the anode, and platinum wire was used as the cathode for electrochemical exfoliation of graphite. The graphite foil and platinum electrode were placed in a 0.1M MgSO4 solution, and electrochemical exfoliation was performed by applying a positive voltage of 10V to the graphite electrode. After the graphite was exfoliated, the product was vacuum filtered with deionized water to obtain exfoliated graphene. The exfoliated graphene was dispersed in deionized water, sonicated for 20 min, and then centrifuged at 3000 r / min for 20 min to form a graphene dispersion with a concentration of 5 mg / ml. The method for preparing the pretreated aniline solution is as follows: Add aniline monomer to 0.5 mol / L hydrochloric acid. The mass-to-volume ratio of aniline to hydrochloric acid is 1:2 (g / ml). After thorough mixing, let stand for 2 hours. After the solution separates into layers, take the lower layer.

2. The supercapacitor according to claim 1, characterized in that, The molar ratio of acrylamide to aniline in the pretreated aniline solution is 1:(6-8).

3. The supercapacitor according to claim 1, characterized in that, In step (3), the molar ratio of aniline to ammonium persulfate in the aniline solution is 1:(0.3-0.5).

4. The supercapacitor according to claim 3, characterized in that, In step (3), the molar ratio of dithiol compound to acrylamide is (0.1-0.2):

1.

5. The supercapacitor according to claim 1, characterized in that, The ultrasonic dispersion temperature for preparing the modified carbon nanotubes is 30-50℃.

6. The supercapacitor according to claim 1, characterized in that, The electrolyte is selected from any one of aqueous electrolytes, organic electrolytes, or solid gel electrolytes; The diaphragm is a porous polymer film or a cellulose membrane.

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