A dual conductive network capacitor and a method of manufacturing the same

Abstract

The application relates to the technical field of capacitors, and discloses a double-conductive network capacitor and a preparation method thereof. The capacitor in the application is assembled by a working electrode, a diaphragm and an electrolyte. The working electrode is prepared by coating and drying slurry made of MXene@PDA-C / PTh nanomaterial, polyvinylidene fluoride and acetylene black. The working electrode can form a double-conductive network with the electrolyte, thereby improving the conductivity and rate performance of the capacitor and the cycle stability of the capacitor.

Description

Technical Field

[0001] This invention relates to the field of capacitor technology, specifically to a dual-conducting-network capacitor and its fabrication method. Background Technology

[0002] Traditional capacitors, especially high-capacity supercapacitors, rely heavily on constructing an efficient electrode conductive network. Early electrodes primarily depended on a single type of conductive agent, such as carbon black or carbon nanotubes. While carbon black can form point-to-point contacts, it tends to form isolated active particles under high-activity material loading, leading to uneven overall conductivity. One-dimensional carbon nanotubes, although capable of constructing long-range pathways, present challenges due to their dispersion and contact impedance. More critically, when electrodes are subjected to bending, stretching, or long-term cycling, this single, fragile conductive network is prone to breakage or contact failure, disrupting charge transport paths, causing a sharp increase in internal resistance, and ultimately leading to capacitance decay and device performance degradation.

[0003] To overcome these limitations, researchers considered combining ionic and electronic conduction to improve capacitor performance. This multi-level structure achieves redundancy and synergy in the electron transport path, maintaining conductivity continuity even under mechanical deformation or high loads through another network. This significantly improves the structural stability, rate performance, and areal capacity of the electrodes, laying a key technological foundation for next-generation high-performance, high-toughness energy storage devices. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a dual-conducting network capacitor and its fabrication method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A dual-conductivity network capacitor includes a working electrode, a separator, and an electrolyte; the working electrode is prepared by coating a nickel foam surface with a slurry of MXene@PDA-C / PTh nanomaterials, polyvinylidene fluoride, and acetylene black, followed by drying; the separator is a polypropylene separator; and the electrolyte is an organic electrolyte.

[0007] The MXene@PDA-C / PTh nanomaterial is made by coating MXene nanosheets with polydopamine, calcining them, and then loading polythiophene nanomaterials.

[0008] Furthermore, the MXene@PDA-C / PTh nanomaterial is specifically prepared by the following steps:

[0009] Step A1: Grind Ti3AlC2 and pass it through an 800-mesh sieve. Place LiF powder in 0.5 mol / L dilute hydrochloric acid and stir in a sealed container for 0.5-1 h. Then add the ground Ti3AlC2 and stir in an oil bath at 35°C for 3 h. Wash until the solution pH > 5. Then add the product to a 2 mol / L sodium hydroxide solution and stir ultrasonically for 30 min. After sealing, stir in an oil bath at 80°C for 2 h. After the reaction is complete, wash until neutral, centrifuge, and vacuum dry to obtain MXene nanosheets.

[0010] Furthermore, in step A1, the ratio of LiF powder, dilute hydrochloric acid, ground Ti3AlC2 and sodium hydroxide solution is 2g:80mL:1.5-2.5g:100mL;

[0011] Step A2: Add Pluronic F127 (template agent) and 1,3,5-trimethylbenzene to an ethanol-water solution (ethanol and deionized water volume ratio of 1:1) and stir thoroughly. After ultrasonically dispersing MXene nanosheets evenly in ethanol, add them to the system and stir evenly. Then add dopamine hydrochloride and stir for 30 min. Slowly add 28 wt% ammonia water and continue stirring for 8-10 h. Filter, wash, and dry. Then place the dried product in a tube furnace for calcination to obtain MXene@PDA-C nanomaterials (MXene nanomaterials coated with polydopamine carbon layer).

[0012] Furthermore, in step A2, the ratio of Pluronic F127, 1,3,5-trimethylbenzene, aqueous ethanol solution, MXene nanosheets, ethanol, dopamine hydrochloride, and ammonia is 2-6 g: 4-12 mL: 200 mL: 0.4-1.2 g: 8-16 mL: 1.4-4.2 g: 2-6 mL;

[0013] Further, the calcination conditions described in step A2 are as follows: calcination temperature of 500-700℃, heating rate of 1-3℃ / min, calcination time of 2h, and carried out under an argon atmosphere;

[0014] Step A3: Thiophene is stirred in a mixture of N-methylformamide and deionized water for 2 hours to ensure thorough mixing. Then, FeCl3 aqueous solution is slowly added, and the pH of the system is adjusted to 4.5. MXene@PDA-C aqueous solution is then added and stirred until homogeneous. The mixture is then transferred to an ice-water bath and stirred continuously for 12 hours. After centrifugation, washing, and freeze-drying, MXene@PDA-C / PTh nanomaterials (polydopamine carbon layer@MXene / polythiophene nanomaterials) are obtained.

[0015] Furthermore, in step A3, the ratio of thiophene, N-methylformamide, deionized water, FeCl3 aqueous solution and MXene@PDA-C aqueous solution is 1-3g:50mL:50mL:50-150mL:20mL;

[0016] Further, the concentration of the FeCl3 aqueous solution in step A3 is 40 mg / mL, and the concentration of the MXene@PDA-C aqueous solution is 10-50 mg / mL;

[0017] Furthermore, step A3 involves adjusting the pH using a 1M nitric acid solution.

[0018] A method for fabricating a dual-conducting-network capacitor includes the following steps:

[0019] Step S1: Mix MXene@PDA-C / PTh nanomaterials, polyvinylidene fluoride and acetylene black in a mass ratio of 8:1:1, then add N-methylpyrrolidone and grind thoroughly. Then coat evenly on the surface of nickel foam with a coating area of ​​1cm×1cm, and then place it in a vacuum dryer at 60℃ to obtain the working electrode.

[0020] Step S2: Separate the two working electrodes prepared in step S1 using a polypropylene diaphragm, then inject electrolyte to assemble them, thus obtaining a dual-conducting network capacitor.

[0021] The beneficial effects of this invention are:

[0022] The capacitor in this invention is assembled from a working electrode, a separator, and an electrolyte. The working electrode is prepared by coating and drying a slurry made of MXene@PDA-C / PTh nanomaterials, polyvinylidene fluoride, and acetylene black. This working electrode can form a dual conductive network with the electrolyte, which not only improves the conductivity and rate performance of the capacitor, but also improves the cycle stability of the capacitor.

[0023] In this invention, the working electrode of the capacitor incorporates MXene@PDA-C / PTh nanomaterials as an active material, enabling the capacitor to possess a double conductive network under the action of the working electrode and electrolyte, thereby improving the overall performance of the capacitor. The MXene nanosheets in this nanomaterial have the advantage of high conductivity, providing a framework for high-speed electron transport for the entire electrode and endowing the capacitor with high rate performance. At the same time, due to its large specific surface area, it can provide a portion of the double-layer capacitance by electrostatically adsorbing electrolyte ions. Furthermore, its two-dimensional layered structure provides a stable and robust substrate for subsequent coating, preventing material agglomeration and maintaining the integrity of the electrode structure. Because MXene nanosheets tend to self-stack during cycling, losing active area and being easily oxidized at their edges, leading to performance degradation, a polydopamine carbon layer serves as both a "spacer" and a "protective layer." It physically isolates the MXene nanosheets and chemically isolates them from oxygen and moisture in the electrolyte, significantly improving cycling stability. The polydopamine carbon layer also contains mesopores, which increase the specific surface area and provide more double-layer formation sites, offering short paths for rapid diffusion of ions in the electrolyte and enhancing rate performance. Furthermore, polydopamine exhibits excellent adhesion before carbonization, ensuring a tight bond with MXene. The carbonized layer establishes a good electronic bridge between MXene and polythiophene, guaranteeing low internal resistance of the overall electrode. The nitrogen-doped carbon layer also possesses excellent conductivity. The outermost layer of polythiophene further contributes to high pseudocapacitance, increasing energy density. Detailed Implementation

[0024] 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.

[0025] Example 1: MXene@PDA-C / PTh nanomaterials were prepared using the following steps:

[0026] Step A1: Grind Ti3AlC2 and pass it through an 800-mesh sieve. Place 2g of LiF powder in 80mL of 0.5mol / L dilute hydrochloric acid and stir for 0.5h. Then add 1.5g of ground Ti3AlC2 and stir in an oil bath at 35℃ for 3h. Wash until the solution pH > 5. Then add the product to 100mL of 2mol / L sodium hydroxide solution and stir ultrasonically for 30min. After sealing, stir in an oil bath at 80℃ for 2h. After the reaction is complete, wash until neutral, centrifuge, and vacuum dry to obtain MXene nanosheets.

[0027] Step A2: Add 2g of Pluronic F127 (template agent) and 4mL of 1,3,5-trimethylbenzene to 200mL of ethanol aqueous solution (ethanol and deionized water volume ratio of 1:1) and stir thoroughly. Disperse 0.4g of MXene nanosheets evenly in 8mL of ethanol by ultrasonication and then add it to the system and stir evenly. Add 1.4g of dopamine hydrochloride and stir for 30min. Slowly add 2mL of 28wt% ammonia water and stir continuously for 8h. Filter, wash, and dry. Then place the dried product in a tube furnace for calcination to obtain MXene@PDA-C nanomaterials. The calcination conditions are: calcination temperature of 500℃, heating rate of 1℃ / min, calcination time of 2h, and calcination is carried out under an argon atmosphere.

[0028] Step A3: Stir 1g of thiophene in a mixture of 50mL N-methylformamide and 50mL deionized water for 2 hours to ensure thorough mixing. Then, slowly add 50mL of 40mg / mL FeCl3 aqueous solution and adjust the pH of the system to 4.5. Next, add 10mg / mL and 20mL of MXene@PDA-C aqueous solution and stir until homogeneous. Transfer the mixture to an ice-water bath and stir continuously for 12 hours. Centrifuge, wash, and freeze-dry to obtain MXene@PDA-C / PTh nanomaterials. Adjust the pH using 1M nitric acid solution.

[0029] Example 2: MXene@PDA-C / PTh nanomaterials were prepared using the following steps:

[0030] Step A1: Grind Ti3AlC2 and pass it through an 800-mesh sieve. Place 2g of LiF powder in 80mL of 0.5mol / L dilute hydrochloric acid and stir for 45min. Then add 2g of ground Ti3AlC2 and stir in an oil bath at 35℃ for 3h. Wash until the solution pH > 5. Then add the product to 100mL of 2mol / L sodium hydroxide solution and stir ultrasonically for 30min. After sealing, stir in an oil bath at 80℃ for 2h. After the reaction is complete, wash until neutral, centrifuge, and vacuum dry to obtain MXene nanosheets.

[0031] Step A2: Add 4g of Pluronic F127 (template agent) and 8mL of 1,3,5-trimethylbenzene to 200mL of ethanol aqueous solution (ethanol and deionized water volume ratio of 1:1) and stir thoroughly. Disperse 0.8g of MXene nanosheets evenly in 12mL of ethanol by ultrasonication and then add it to the system and stir evenly. Add 2.8g of dopamine hydrochloride and stir for 30min. Slowly add 4mL of 28wt% ammonia water and stir continuously for 9h. Filter, wash, and dry. Then place the dried product in a tube furnace for calcination to obtain MXene@PDA-C nanomaterials. The calcination conditions are: calcination temperature of 600℃, heating rate of 2℃ / min, calcination time of 2h, and calcination is carried out under an argon atmosphere.

[0032] Step A3: Stir 2g of thiophene in a mixture of 50mL N-methylformamide and 50mL deionized water for 2h to ensure thorough mixing. Then slowly add 100mL of 40mg / mL FeCl3 aqueous solution and adjust the pH of the system to 4.5. Next, add 30mg / mL of 20mL MXene@PDA-C aqueous solution and stir until homogeneous. Transfer the mixture to an ice-water bath and stir continuously for 12h. Centrifuge, wash, and freeze-dry to obtain MXene@PDA-C / PTh nanomaterials. Adjust the pH using 1M nitric acid solution.

[0033] Example 3: The MXene@PDA-C / PTh nanomaterial was prepared by the following steps:

[0034] Step A1: Grind Ti3AlC2 and pass it through an 800-mesh sieve. Place 2g of LiF powder in 80mL of 0.5mol / L dilute hydrochloric acid and stir for 1h. Then add 2.5g of ground Ti3AlC2 and stir in an oil bath at 35℃ for 3h. Wash until the solution pH > 5. Then add the product to 100mL of 2mol / L sodium hydroxide solution and stir ultrasonically for 30min. After sealing, stir in an oil bath at 80℃ for 2h. After the reaction is complete, wash until neutral, centrifuge, and vacuum dry to obtain MXene nanosheets.

[0035] Step A2: Add 6g of Pluronic F127 (template agent) and 12mL of 1,3,5-trimethylbenzene to 200mL of ethanol aqueous solution (ethanol and deionized water volume ratio of 1:1) and stir thoroughly. Disperse 1.2g of MXene nanosheets evenly in 16mL of ethanol by ultrasonication and then add it to the system and stir evenly. Add 4.2g of dopamine hydrochloride and stir for 30min. Slowly add 6mL of 28wt% ammonia water and stir continuously for 10h. Filter, wash, and dry. Then place the dried product in a tube furnace for calcination to obtain MXene@PDA-C nanomaterials. The calcination conditions are: calcination temperature of 700℃, heating rate of 3℃ / min, calcination time of 2h, and calcination is carried out under an argon atmosphere.

[0036] Step A3: Stir 3g of thiophene in a mixture of 50mL N-methylformamide and 50mL deionized water for 2 hours to ensure thorough mixing. Then, slowly add 150mL of 40mg / mL FeCl3 aqueous solution and adjust the pH of the system to 4.5. Next, add 50mg / mL of 20mL MXene@PDA-C aqueous solution and stir until homogeneous. Transfer the solution to an ice-water bath and stir continuously for 12 hours. Centrifuge, wash, and freeze-dry to obtain MXene@PDA-C / PTh nanomaterials. Adjust the pH using 1M nitric acid solution.

[0037] Example 4: A method for fabricating a dual-conductive network capacitor includes the following steps:

[0038] Step S1: Mix 0.8g of MXene@PDA-C / PTh nanomaterial prepared in Example 1, 0.1g of polyvinylidene fluoride and 0.1g of acetylene black, then add 7mL of N-methylpyrrolidone and grind thoroughly. Then coat evenly on the surface of nickel foam with a coating area of ​​1cm×1cm, and then place it in a vacuum dryer at 60℃ to obtain the working electrode.

[0039] Step S2: Separate the two working electrodes prepared in step S1 using a polypropylene diaphragm, then inject electrolyte (NewZybond DLC301 electrolyte) and assemble them to obtain a dual-conductive network capacitor.

[0040] Example 5: A method for fabricating a dual-conducting network capacitor includes the following steps:

[0041] Step S1: Mix 0.8g of MXene@PDA-C / PTh nanomaterial prepared in Example 2, 0.1g of polyvinylidene fluoride and 0.1g of acetylene black, then add 7mL of N-methylpyrrolidone and grind thoroughly. Then coat evenly on the surface of nickel foam with a coating area of ​​1cm×1cm, and then place it in a vacuum dryer at 60℃ to obtain the working electrode.

[0042] Step S2: Separate the two working electrodes prepared in step S1 using a polypropylene diaphragm, then inject electrolyte (NewZybond DLC301 electrolyte) and assemble them to obtain a dual-conductive network capacitor.

[0043] Example 6: A method for fabricating a dual-conducting network capacitor includes the following steps:

[0044] Step S1: Mix 0.8g of MXene@PDA-C / PTh nanomaterial prepared in Example 3, 0.1g of polyvinylidene fluoride and 0.1g of acetylene black, then add 7mL of N-methylpyrrolidone and grind thoroughly. Then coat evenly on the surface of nickel foam with a coating area of ​​1cm×1cm, and then place it in a vacuum dryer at 60℃ to obtain the working electrode.

[0045] Step S2: Separate the two working electrodes prepared in step S1 using a polypropylene diaphragm, then inject electrolyte (NewZybond DLC301 electrolyte) and assemble them to obtain a dual-conductive network capacitor.

[0046] Comparative Example 1: This comparative example is a dual-conductive network capacitor. The difference from Example 6 is that the MXene nanosheets prepared in Example 3 are used instead of the MXene@PDA-C / PTh nanomaterials prepared in Example 3. All other aspects are the same.

[0047] Comparative Example 2: This comparative example is a dual-conductive network capacitor. The difference from Example 6 is that the MXene@PDA-C nanomaterial prepared in Example 3 is used instead of the MXene@PDA-C / PTh nanomaterial prepared in Example 3. All other aspects are the same.

[0048] Comparative Example 3: This comparative example is a dual-conductive network capacitor. The difference from Example 6 is that MXene / PTh nanomaterials are used instead of the MXene@PDA-C / PTh nanomaterials prepared in Example 3.

[0049] The above MXene / PTh nanomaterials were prepared by the following steps:

[0050] Step B1: Grind Ti3AlC2 and pass it through an 800-mesh sieve. Place 2g of LiF powder in 80mL of 0.5mol / L dilute hydrochloric acid and stir for 1h. Then add 2.5g of ground Ti3AlC2 and stir in an oil bath at 35℃ for 3h. Wash until the solution pH > 5. Then add the product to 100mL of 2mol / L sodium hydroxide solution and stir ultrasonically for 30min. After sealing, stir in an oil bath at 80℃ for 2h. After the reaction is complete, wash until neutral, centrifuge, and vacuum dry to obtain MXene nanosheets.

[0051] Step B2: Stir 3g of thiophene in a mixture of 50mL N-methylformamide and 50mL deionized water for 2 hours to ensure thorough mixing. Then, slowly add 150mL of 40mg / mL FeCl3 aqueous solution and adjust the pH of the system to 4.5. Next, add 50mg / mL of 20mL MXene nanosheet aqueous solution and stir until homogeneous. Transfer the solution to an ice-water bath and stir continuously for 12 hours. Centrifuge, wash, and freeze-dry to obtain MXene@PDA-C / PTh nanomaterials. Adjust the pH using 1M nitric acid solution.

[0052] The performance of the dual-conductive network capacitors prepared in Examples 4-6 and Comparative Examples 1-3 was tested:

[0053] The specific capacitance of the capacitor during operation was tested using the Blue Battery Testing System (at a current density of 1 A / g), and the capacitance retention rate was evaluated after 10,000 GCD tests. The current density was then increased to 10 A / g for further testing to assess the rate performance.

[0054] The test results are shown in Table 1:

[0055] Table 1: Performance Test Results

[0056]

[0057] As can be seen from Table 1, the dual-conductive network capacitor prepared by this invention not only has excellent conductivity, but also excellent cycle stability, specific capacitance and high rate performance, and has good application prospects.

[0058] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. A dual-conducting-network capacitor, characterized in that, It includes a working electrode, a diaphragm, and an electrolyte; the working electrode is prepared by coating a slurry of MXene@PDA-C / PTh nanomaterials, polyvinylidene fluoride, and acetylene black onto a nickel foam surface and then drying it; the diaphragm is a polypropylene diaphragm; and the electrolyte is an organic electrolyte. The MXene@PDA-C / PTh nanomaterial is made by coating MXene nanosheets with polydopamine, calcining them, and then loading polythiophene nanomaterials. The MXene@PDA-C / PTh nanomaterial is prepared by the following steps: Step A1: Grind Ti3AlC2 and pass it through an 800-mesh sieve. Place LiF powder in 0.5 mol / L dilute hydrochloric acid and stir in a sealed container for 0.5-1 h. Then add the ground Ti3AlC2 and stir in an oil bath at 35°C for 3 h. Wash until the solution pH > 5. Then add the product to a 2 mol / L sodium hydroxide solution and stir ultrasonically for 30 min. After sealing, stir in an oil bath at 80°C for 2 h. After the reaction is complete, wash until neutral, centrifuge, and vacuum dry to obtain MXene nanosheets. Step A2: Pluronic F127 and 1,3,5-trimethylbenzene were added to an ethanol aqueous solution and stirred thoroughly. MXene nanosheets were ultrasonically dispersed in ethanol and then added to the system and stirred evenly. Dopamine hydrochloride was then added and stirred for 30 min. 28 wt% ammonia water was slowly added dropwise and stirred continuously for 8-10 h. The mixture was filtered, washed, and dried. The dried product was then calcined in a tube furnace to obtain MXene@PDA-C nanomaterials. Step A3: Thiophene is stirred in a mixture of N-methylformamide and deionized water for 2 hours to ensure thorough mixing. Then, FeCl3 aqueous solution is slowly added and the pH of the system is adjusted to 4.

5. MXene@PDA-C aqueous solution is then added and stirred until homogeneous. The mixture is then transferred to an ice-water bath and stirred continuously for 12 hours. After centrifugation, washing, and freeze-drying, MXene@PDA-C / PTh nanomaterials are obtained.

2. A dual-conducting-network capacitor according to claim 1, characterized in that, In step A1, the ratio of LiF powder, dilute hydrochloric acid, ground Ti3AlC2 and sodium hydroxide solution is 2g:80mL:1.5-2.5g:100mL.

3. A dual-conducting-network capacitor according to claim 1, characterized in that, In step A2, the ratio of Pluronic F127, 1,3,5-trimethylbenzene, aqueous ethanol solution, MXene nanosheets, ethanol, dopamine hydrochloride, and ammonia is 2-6g:4-12mL:200mL:0.4-1.2g:8-16mL:1.4-4.2g:2-6mL.

4. A dual-conducting-network capacitor according to claim 1, characterized in that, The calcination conditions described in step A2 are as follows: calcination temperature of 500-700℃, heating rate of 1-3℃ / min, calcination time of 2h, and calcination under an argon atmosphere.

5. A dual-conducting-network capacitor according to claim 1, characterized in that, In step A3, the ratio of thiophene, N-methylformamide, deionized water, FeCl3 aqueous solution and MXene@PDA-C aqueous solution is 1-3g:50mL:50mL:50-150mL:20mL.

6. A dual-conducting-network capacitor according to claim 1, characterized in that, The concentration of the FeCl3 aqueous solution in step A3 is 40 mg / mL, and the concentration of the MXene@PDA-C aqueous solution is 10-50 mg / mL.

7. A dual-conducting-network capacitor according to claim 1, characterized in that, The pH of the system described in step A3 is adjusted using a 1M nitric acid solution.

8. A method for preparing a dual-conducting network capacitor according to any one of claims 1-7, characterized in that, Includes the following steps: Step S1: Mix MXene@PDA-C / PTh nanomaterials, polyvinylidene fluoride and acetylene black in a mass ratio of 8:1:1, then add N-methylpyrrolidone and grind thoroughly. Then coat evenly on the surface of nickel foam with a coating area of ​​1cm×1cm, and then place it in a vacuum dryer at 60℃ to obtain the working electrode. Step S2: Separate the two working electrodes prepared in step S1 using a polypropylene diaphragm, then inject electrolyte to assemble them, thus obtaining a dual-conducting network capacitor.

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