A method for preparing supercapacitor carbon by ultrasonic atomization, supercapacitor carbon and supercapacitor electrode

Abstract

The application belongs to the field of electrochemical energy storage materials and device manufacturing, and particularly relates to a method for preparing supercapacitor carbon by ultrasonic atomization, supercapacitor carbon and a supercapacitor electrode. The method prepares slurry from carbonized material, bridging conductive agent and composite binder, forms spherical droplets through ultrasonic atomization, and then performs drying, pre-activation and CO2 etching to prepare supercapacitor carbon with integrated three-dimensional network. Through the synergistic process of'spherical template construction-networking reconstruction-etching modification', the method realizes controllable transformation of material structure, optimizes tap density, pore system and conductive network of the electrode, so as to obtain an electrode with high specific capacity, excellent rate performance and cycle stability, and the process is environmentally friendly and coherent, and is suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage materials and device manufacturing, specifically relating to a method for preparing supercapacitor carbon by ultrasonic atomization, supercapacitor carbon, and supercapacitor electrodes. Background Technology

[0002] Supercapacitors, as an important class of electrochemical energy storage devices, possess significant advantages in power density and cycle life, making them irreplaceable in many fields. However, their insufficient energy density, especially volumetric energy density, limits their widespread application in space-constrained scenarios. The core of this problem lies in the contradiction between the microstructure and macroscopic properties of commercially available porous carbon electrode materials: to obtain a high specific surface area for charge storage, the material typically exhibits a porous and irregular powder morphology, resulting in extremely low tap density and chaotic pore channels during electrode fabrication. The former directly leads to a large electrode volume, while the latter causes ions and electrons to face high impedance during charging and discharging, especially at high current rates, resulting in severe capacity loss. Therefore, the market has a clear and urgent need for an innovative fabrication method that can synergistically improve the electrode tap density and charge transport kinetics performance from the structural origin.

[0003] To address these challenges, existing research and technological improvements primarily focus on the physicochemical modification of activated carbon materials. For example, efforts are made to construct a more ideal pore system within the material by improving precursor treatment methods or introducing different pore-forming agents; alternatively, multiple nanoscale conductive media are incorporated into the electrode slurry to reduce overall resistance. While these methods may be effective in improving specific performance indicators, their effects are often isolated or even mutually exclusive.

[0004] In-depth analysis reveals inherent limitations in addressing structural synergy issues with existing technologies. Many methods aimed at increasing specific surface area or conductivity often sacrifice mechanical strength or packing density, leading to a decrease in the macroscopic mechanical properties or volumetric capacity of the electrode. Conversely, any attempt to enhance material density or improve particle packing may inadvertently block the channels required for ion transport or reduce active sites, thereby impairing specific capacity and rate performance. More critically, these methods typically focus on the mixing or post-modification of the final product, failing to achieve integrated design and precise control of particle morphology, internal porosity, and interparticle connectivity from the initial stages of material forming. As a result, the prepared electrode materials exhibit compromises in microstructure, failing to simultaneously integrate the three key elements of high density, high ion accessibility surface, and efficient electron channels into a stable and homogeneous system.

[0005] Therefore, developing a new process that can construct high-performance electrode materials from the bottom up in an integrated manner is of great significance for breaking through the current performance bottleneck of supercapacitors. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a method for preparing supercapacitor carbon via ultrasonic atomization, as well as the supercapacitor carbon and supercapacitor electrodes. This invention involves blending carbonized material powder, a bridging conductive agent, and a binder solution to form a slurry, and then using ultrasonic atomization technology to transform it into a spherical precursor with uniform particle size. Subsequently, a two-stage activation process, including low-temperature pre-activation and high-temperature CO2 etching, is employed to process the precursor, providing an innovative solution for achieving high tap density, excellent rate performance, and high volumetric energy density in the electrodes.

[0007] The first objective of this invention is achieved through the following technical solution:

[0008] A method for preparing supercapacitor carbon by ultrasonic atomization, characterized by comprising the following steps:

[0009] (1) The carbonized powder, bridging conductive agent, and binder solution are dispersed in a solvent at a mass ratio of (80-95):(5-20):(2-10) to form a mixed slurry, wherein the solid content of the mixed slurry is 10-30 wt%.

[0010] (2) In an ultrasonic atomizing device, the mixed slurry is ultrasonically atomized to form droplets with a particle size of 20-100 μm, and dried and solidified at 150-300℃ under an inert atmosphere to obtain precursor particles;

[0011] (3) The precursor particles are heated to 300-500℃ at 2-8℃ / min under an inert atmosphere and pre-activated at low temperature for 1-3 hours to obtain pre-activated activated carbon.

[0012] (4) The pre-activated carbon is heated to 800-950℃ in a CO2 atmosphere at 5-10℃ / min and etched for 1-4 hours to obtain supercapacitor carbon.

[0013] Preferably, in step (1), the carbonized material powder is porous activated carbon powder that has undergone preliminary carbonization of biomass.

[0014] Preferably, in step (1), the bridging conductive agent is graphene oxide and / or carbon nanotubes.

[0015] More preferably, the bridging conductive agent is graphene oxide, with a sheet size of 1-20 μm.

[0016] More preferably, the bridging conductive agent is a carbon nanotube with a diameter of 5-50 nm and a length of 1-20 μm.

[0017] Preferably, in step (1), the adhesive solution is a composite aqueous solution of sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR).

[0018] More preferably, the mass ratio of sodium carboxymethyl cellulose to styrene-butadiene rubber in the adhesive solution is 1.5:1 to 1:2.

[0019] More preferably, the preparation method of the adhesive solution includes: first dissolving 0.5-2 parts by weight of sodium carboxymethyl cellulose in 15-50 parts by weight of water, dispersing it evenly at a stirring speed of 500-1500 rpm to form a transparent or semi-transparent solution; then adding 0.5-4 parts by weight of styrene-butadiene rubber emulsion, mixing it evenly at a stirring speed of 300-800 rpm to obtain a composite aqueous solution of sodium carboxymethyl cellulose and styrene-butadiene rubber.

[0020] More preferably, the pH value of the adhesive solution is 8-10.

[0021] Preferably, in step (1), the solvent includes one or more of water, ethanol, and methanol.

[0022] Preferably, the solid content of the mixed slurry is 15-25 wt%.

[0023] Preferably, in step (1), the mass ratio of the carbonized powder, the bridging conductive agent, and the binder solution is (80-90):(5-15):(4-6).

[0024] Preferably, in step (2), the parameters set for the ultrasonic atomizing device are: frequency 20-100kHz, power density 0.5-3.0W / cm². 2 Atomization rate: 0.1-5.0 L / h.

[0025] More preferably, the frequency of the ultrasonic atomizing device is set to 60-100kHz.

[0026] More preferably, the power density of the ultrasonic atomizing device is set to 1.5-2.5 W / cm². 2 .

[0027] More preferably, the ultrasonic atomizing device is set to an atomization rate of 0.5-2.0 L / h.

[0028] Preferably, in step (2), the inert atmosphere is nitrogen or argon.

[0029] Preferably, in step (2), the drying and curing temperature is 200-280℃.

[0030] Preferably, the heating rate in step (3) is 5-8℃ / min.

[0031] Preferably, in step (3), the low-temperature pre-activation temperature is 350-450℃.

[0032] Preferably, in step (3), the low-temperature pre-activation time is 1.5-2.5h.

[0033] Preferably, in step (4), the gas flow rate of CO2 is 50-200 mL / min.

[0034] Preferably, the heating rate in step (4) is 7-10℃ / min.

[0035] Preferably, in step (4), the CO2 etching time is 2-3 hours.

[0036] This method employs ultrasonic atomization granulation of a mixed slurry containing carbonized material, bridging conductive agent, and water-based binder, combined with low-temperature pre-activation and high-temperature CO2 etching. Through a series of synergistic effects, a capacitor carbon for supercapacitors with high tap density, regular hierarchical channels, and a highly efficient three-dimensional conductive network is prepared. The core principle is as follows: First, the mixed slurry is dispersed into uniformly sized spherical droplets through ultrasonic atomization. The stacking of these droplets forms beneficial secondary pores during the activation process. Simultaneously, the bridging conductive agent facilitates the connection and conductivity between the droplet particles, aiding in the construction of a three-dimensional conductive network and a more precise hierarchical porous structure. The resulting pore system originates from both the etching-created pores within the particles and the uniform gaps formed by the regular stacking of particles, together constructing a stable three-dimensional structure conducive to efficient electron and ion transport.

[0037] Specifically, firstly, ultrasonic atomization technology uses high-frequency vibration to break the slurry into uniformly sized microdroplets. The cavitation effect ensures the uniform dispersion of all components within the slurry, preventing particle agglomeration and directly forming spherical precursor particles, providing an ideal initial template for subsequent construction of regular structures. Secondly, the water-based binder system composed of sodium carboxymethyl cellulose and styrene-butadiene rubber in a specific ratio is not only environmentally friendly and safe, but its hydroxyl and carboxyl groups on the molecular chain can form hydrogen bonds with active particles, playing an excellent role in thickening and dispersing. The elasticity of styrene-butadiene rubber can buffer the stress during subsequent heat treatment and pressing, ensuring the stability of the slurry and the integrity of the particle structure. Thirdly, the introduction of graphene oxide or carbon nanotubes as bridging conductive agents not only acts as a "bridge" to physically connect adjacent particles during ultrasonic dispersion and subsequent heat treatment, but also forms strong chemical bonds with the carbon matrix during the pre-activation and etching stages, as the binder carbonizes and the particle surface is activated. This constructs a three-dimensional continuous conductive network throughout the entire electrode material, significantly reducing electron transport impedance. Fourth, the low-temperature pre-activation process at 300-500℃ causes the binder and organic components to slowly decompose and initially carbonize, forming flexible carbonaceous connection points inside and between particles. This further stabilizes the network structure established by the bridging conductive agent, preventing structural collapse during subsequent high-temperature processing. Fifth, the CO2 physical etching process at 800-950℃ synergistically modifies the initially networked porous structure. CO2 gas diffuses through the connected pores, gently etching the carbon skeleton. On the one hand, it further creates and expands micropores and mesopores inside the particles, optimizing the specific surface area and pore size distribution. On the other hand, the etching also occurs at the connections between particles, strengthening bridging points and increasing the contact interface, thereby simultaneously improving the porosity and conductivity of the entire three-dimensional network structure.

[0038] The second objective of this invention is achieved through the following technical solution:

[0039] A supercapacitor carbon, prepared by the above-described ultrasonic atomization method, has a specific surface area of ​​1500-2500 m². 2 / g, wherein the mesoporosity is 40%-55% in the pore size range of 2-50nm.

[0040] The third objective of this invention is achieved through the following technical solution:

[0041] A method for preparing a supercapacitor electrode includes the following steps: mixing the supercapacitor carbon as described above with a conductive agent and a reinforcing binder, and then pressing it into shape to obtain the electrode.

[0042] Preferably, the conductive agent is a carbon black material, including one or two of acetylene black and super conductive carbon black (Super P).

[0043] Preferably, the reinforcing adhesive is a polytetrafluoroethylene emulsion or a composite aqueous solution of sodium carboxymethyl cellulose and styrene-butadiene rubber.

[0044] Preferably, the pressing pressure is 5-20 MPa.

[0045] The fourth objective of this invention is achieved through the following technical solution:

[0046] A supercapacitor electrode is prepared by the above-described method for preparing a supercapacitor electrode.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] 1. This invention creatively prepares homogeneous slurry directly into spherical precursors through ultrasonic atomization, and uses these precursors as structural templates to achieve a morphological and structural transformation from "discrete spheres" to "integrated three-dimensional sponge networks" through subsequent heat treatment. This method fundamentally revolutionizes the construction of electrode materials. The resulting integrated network possesses both high mechanical strength and abundant intrinsic porosity, achieving a balance between high tap density and efficient ion transport channels, thus overcoming the density and porosity contradiction caused by the simple stacking of traditional powders.

[0049] 2. This invention, through the synergistic effect of a water-based composite binder and a bridging conductive agent, not only ensures dispersion stability and anti-settling properties in the slurry stage, making the droplet particles after ultrasonic atomization more uniform, which directly affects subsequent batch consistency and product quality; but also crucially achieves in-situ construction of chemical bridging between particles and conductive network during heat treatment. This three-dimensional conductive network runs through the entire sponge-like electrode bulk phase, significantly reducing electron transport impedance, thereby endowing the electrode with excellent rate performance and structural stability.

[0050] 3. The two-step heat treatment process of low-temperature pre-activation and high-temperature CO2 etching employed in this invention achieves controllable construction of a multi-level porous structure and excellent preservation of its spherical morphology. Pre-activation stabilizes the particle framework, while subsequent CO2 etching gently and selectively creates a high proportion of mesopores, thereby simultaneously obtaining a high specific surface area and an ideal pore size distribution.

[0051] 4. The electrode product prepared by the method of this invention is essentially a three-dimensional continuous sponge-like structure integrating pores and a conductive network. This structure achieves multiple advantages through synergy, including high density, high ion accessibility, high electronic conductivity, and excellent mechanical integrity, effectively solving the bottleneck problem of mutual constraints among these performance indicators in traditional electrode materials.

[0052] 5. The overall process route of this invention is environmentally friendly, with precise and consistent parameters. The molding process from homogeneous slurry to high-performance electrode is clear and controllable, with good process repeatability and potential for large-scale production, providing a reliable and efficient solution for the actual manufacturing of high-performance supercapacitor carbon. Attached Figure Description

[0053] Figure 1 Here is a SEM image of the supercapacitor carbon prepared in Example 1;

[0054] Figure 2 The image shows a SEM image of the capacitor carbon prepared in Comparative Example 1. Detailed Implementation

[0055] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with embodiments, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0056] The present invention will be further illustrated by specific embodiments below, but the scope of protection of the present invention is not limited thereto.

[0057] The materials used in the embodiments and comparative examples of this invention are described below:

[0058] The carbonized powder is a pre-carbonized precursor (carbonized material) produced by Chengde Asia-Europe Carbon Industry Co., Ltd.

[0059] The graphene oxide was produced by Nanjing Xianfeng Nanomaterials Technology Co., Ltd., with sheet sizes ranging from 1 to 10 μm.

[0060] The carbon nanotubes are produced by Shenzhen Nanoport Co., Ltd., with a diameter of 10-20 nm and a length of 10-20 μm.

[0061] Sodium carboxymethyl cellulose (CMC) is produced by Shanghai Aladdin Biochemical Technology Co., Ltd., with a viscosity of 800-1200 mPa·s;

[0062] The styrene-butadiene rubber (SBR) emulsion (solid content 48wt%) was produced by Zeon Corporation of Japan.

[0063] Polyvinylidene fluoride (PVDF) is produced by Arkema, a French company.

[0064] N-methylpyrrolidone (NMP), high-purity nitrogen, and carbon dioxide are all commercially available industrial-grade products.

[0065] Example 1

[0066] The preparation method of the supercapacitor carbon and electrode in Example 1 includes the following steps:

[0067] (1) Dissolve 1.5 parts by weight of sodium carboxymethyl cellulose in 30 parts by weight of deionized water and disperse it at a stirring speed of 1000 rpm until it is completely dissolved to form a transparent solution; then add 1.0 parts by weight of styrene-butadiene rubber latex and mix it evenly at a stirring speed of 500 rpm to obtain a CMC-SBR composite adhesive solution. Adjust the pH value of the solution to 9 with ammonia water.

[0068] (2) Weigh the carbonized powder, graphene oxide and the binder solution obtained in step (1) in a mass ratio of 85:10:5, add them together to deionized water, stir evenly with a high-speed disperser, and adjust the overall solid content of the slurry to 20wt% to obtain a mixed slurry.

[0069] (3) The mixed slurry obtained in step (2) is fed into an ultrasonic atomizing device, and the ultrasonic frequency is set to 60 kHz and the power density is 1.5 W / cm³. 2 The atomization rate was 1.0 L / h to obtain droplets; the droplets were dried and solidified at 250℃ under nitrogen atmosphere protection to obtain spherical precursor particles.

[0070] (4) Place the spherical precursor particles obtained in step (3) in a tube furnace, and heat them to 400°C at a heating rate of 5°C / min under a nitrogen atmosphere, and keep them at this temperature for 2 hours to obtain pre-activated activated carbon.

[0071] (5) The pre-activated carbon from step (4) was further processed in a tube furnace. The atmosphere was switched to carbon dioxide, the gas flow rate was controlled at 100 mL / min, and the temperature was increased to 850℃ at a rate of 7℃ / min. Etching was performed at this temperature for 2 hours to obtain etched particles, which are the supercapacitor carbon. The average particle size (D50) of these particles is 58 μm. The surface morphology of the supercapacitor carbon was observed using a scanning electron microscope. Figure 1 The surface SEM image shown reveals a clear carbon skeleton with even and regular pores and well-developed, dense porosity.

[0072] (6) The supercapacitor carbon obtained in step (5) is mixed evenly with 3% acetylene black conductive agent and 5% polytetrafluoroethylene emulsion, and then pressed into a disc-shaped supercapacitor electrode with a diameter of 12 mm under a pressure of 10 MPa.

[0073] Example 2

[0074] The preparation method of supercapacitor carbon and electrodes in Example 2 is the same as that in Example 1, except for step (1):

[0075] (1) Dissolve 1.0 parts by weight of sodium carboxymethyl cellulose in 30 parts by weight of deionized water and disperse it at a stirring speed of 1000 rpm until it is completely dissolved; then add 2.0 parts by weight of styrene-butadiene rubber latex and mix it evenly at a stirring speed of 500 rpm to obtain a CMC-SBR composite adhesive solution. Adjust the pH of the solution to 9 with ammonia.

[0076] Example 3

[0077] The preparation method of supercapacitor carbon and electrodes in Example 3 is the same as that in Example 1 in steps (1), (2), (4)-(6), except for step (3):

[0078] (3) The mixed slurry obtained in step (2) is fed into an ultrasonic atomizing device, and the ultrasonic frequency is set to 100 kHz and the power density is 2.5 W / cm³. 2 The atomization rate was 1.0 L / h to obtain droplets; the droplets were dried and solidified at 250℃ under nitrogen atmosphere protection to obtain spherical precursor particles.

[0079] Example 4

[0080] The preparation method of supercapacitor carbon and electrodes in Example 4 is the same as that in Example 1 in steps (1)-(3), (5), and (6), except for step (4):

[0081] (4) Place the precursor particles obtained in step (3) in a tube furnace, and heat them to 300°C at a heating rate of 5°C / min under a nitrogen atmosphere, and keep them at this temperature for 2 hours to obtain pre-activated activated carbon.

[0082] Example 5

[0083] The preparation method of supercapacitor carbon and electrodes in Example 5 is the same as that in Example 1, except for step (5):

[0084] (5) The activated carbon pre-activated in step (4) is further processed in a tube furnace. The atmosphere is switched to carbon dioxide, the gas flow rate is controlled at 100 mL / min, the temperature is raised to 950℃ at a heating rate of 7℃ / min, and etched at this temperature for 4 hours to obtain supercapacitor carbon.

[0085] Example 6

[0086] The preparation method of supercapacitor carbon and electrodes in Example 6 is the same as that in Example 1, except for step (2):

[0087] (2) Weigh the carbonized powder, graphene oxide and the binder solution obtained in step (1) in a mass ratio of 80:20:5, add them together to deionized water, stir evenly with a high-speed disperser, and adjust the overall solid content of the slurry to 20wt% to obtain a mixed slurry.

[0088] Example 7

[0089] The preparation method of supercapacitor carbon and electrodes in Example 7 is the same as that in Example 1 in steps (1) and (3)-(6), except for step (2):

[0090] (2) Weigh the carbonized powder, graphene oxide and the binder solution obtained in step (1) in a mass ratio of 85:10:5, add them together to deionized water, stir evenly with a high-speed disperser, and adjust the overall solid content of the slurry to 15wt% to obtain a mixed slurry.

[0091] Example 8

[0092] The preparation method of supercapacitor carbon and electrodes in Example 8 is the same as that in Example 1 in steps (2), (4), and (6), except for steps (1), (3), and (5):

[0093] (1) Dissolve 1.0 parts by weight of sodium carboxymethyl cellulose in 30 parts by weight of deionized water and disperse it at a stirring speed of 1000 rpm until it is completely dissolved; then add 2.0 parts by weight of styrene-butadiene rubber latex and mix it evenly at a stirring speed of 500 rpm to obtain a CMC-SBR composite adhesive solution. Adjust the pH of the solution to 9 with ammonia.

[0094] (3) The mixed slurry obtained in step (2) is fed into an ultrasonic atomizing device, and the ultrasonic frequency is set to 100 kHz and the power density is 2.5 W / cm³. 2 The atomization rate was 1.0 L / h to obtain droplets; the droplets were dried and solidified at 250℃ under nitrogen atmosphere protection to obtain spherical precursor particles.

[0095] (5) The activated carbon pre-activated in step (4) is further processed in a tube furnace. The atmosphere is switched to carbon dioxide, the gas flow rate is controlled at 100 mL / min, the temperature is raised to 950℃ at a heating rate of 7℃ / min, and etched at this temperature for 2 hours to obtain supercapacitor carbon.

[0096] Comparative Example 1

[0097] The preparation method of the capacitor carbon and electrode in Comparative Example 1 is the same as that in Example 1, except for step (3):

[0098] (3) The mixed slurry obtained in step (2) is dried and granulated using a centrifugal spray dryer. The air inlet temperature is set to 250℃ and the atomizing disc speed is 20000 rpm to obtain irregularly shaped dried precursor particles.

[0099] The surface morphology of the capacitor carbon obtained in this comparative example was observed using a scanning electron microscope, and the results were obtained. Figure 2 The surface SEM image shown reveals that the carbon skeleton has a complex morphology, varying pore sizes, irregular and disordered appearance, and collapsed and tortuous pores.

[0100] Comparative Example 2

[0101] The preparation method of the supercapacitor carbon and electrode in Comparative Example 2 is the same as that in Example 1, except for step (2):

[0102] (2) Weigh the carbonized powder and the binder solution obtained in step (1) at a mass ratio of 95:5, add them together to deionized water, stir evenly with a high-speed disperser, and adjust the overall solid content of the slurry to 20wt% to obtain a mixed slurry.

[0103] Comparative Example 3

[0104] The preparation method of the supercapacitor carbon and electrode in Comparative Example 3 is the same as that in Example 1, except for steps (1) and (2):

[0105] (1) Dissolve polyvinylidene fluoride powder in N-methylpyrrolidone solvent and stir until completely dissolved to prepare a PVDF / NMP adhesive solution with a mass fraction of 5%.

[0106] (2) Weigh the carbonized powder, graphene oxide, and the PVDF / NMP binder solution obtained in step (1) at a mass ratio of 85:10:5, add them together to the NMP solvent, stir evenly with a high-speed disperser, and adjust the overall solid content of the slurry to 20wt% to obtain a mixed slurry.

[0107] Comparative Example 4

[0108] The preparation method of the supercapacitor carbon and electrode in Comparative Example 4 is the same as that in Example 1, except for step (5):

[0109] (5) The activated carbon pre-activated in step (4) is further processed in a tube furnace. The atmosphere is switched to carbon dioxide, the gas flow rate is controlled at 100 mL / min, the temperature is raised to 700℃ at a heating rate of 7℃ / min, and etched at this temperature for 2 hours to obtain capacitor carbon.

[0110] Comparative Example 5

[0111] The preparation method of the supercapacitor carbon and electrode in Comparative Example 5 is the same as that in Example 1, except that step (5) is different:

[0112] (5) The activated carbon pre-activated in step (4) is further processed in a tube furnace. The atmosphere is switched to carbon dioxide, the gas flow rate is controlled at 100 mL / min, the temperature is raised to 1000℃ at a heating rate of 7℃ / min, and etched at this temperature for 2 hours to obtain capacitor carbon.

[0113] Comparative Example 6

[0114] The preparation method of the supercapacitor carbon and electrode of Comparative Example 6 is the same as that of Example 1 in steps (1)-(3), (5) and (6), except that step (4) low-temperature pre-activation is not performed.

[0115] The electrode materials prepared in Examples 1-8 and Comparative Examples 1-6 were tested for tap density, specific surface area, pore size distribution and electrochemical performance. The results are shown in Table 1 below.

[0116] The testing methods and standards are as follows:

[0117] Tap density test: Take a certain mass of sieved particles and measure the density using a tap density meter (JZ-1). The unit is g / cm³. 3 .

[0118] Specific surface area and pore size distribution were tested using nitrogen adsorption-desorption method (ASAP 2460). The specific surface area was calculated using the BET equation, and the mesopore (2-50 nm) volume distribution was calculated using the BJH model.

[0119] Electrochemical performance testing: Using the prepared electrode disc as the working electrode, a platinum sheet as the counter electrode, and Hg / HgO as the reference electrode, cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests were performed in 6 mol / L KOH electrolyte using an electrochemical workstation (CHI760E). Specific capacitance was calculated from the GCD curve at a current density of 0.5 A / g using the formula C = (I × Δt) / (m × ΔV), where I is the current, Δt is the discharge time, m is the mass of the active material, and ΔV is the discharge voltage window (subtracting IR drop). Rate performance was expressed as the percentage of specific capacitance at 10 A / g current density to that at 0.5 A / g current density (capacity retention).

[0120] Table 1. Performance test results of batteries in the examples and comparative examples.

[0121]

[0122] Example 1 serves as a baseline, demonstrating the basic performance of the method of the present invention, with a tap density of 0.76 g / cm³.3 Its specific capacitance (185F / g) and rate performance (82%) are both at an excellent level. Figure 1 The SEM images clearly show that the carbon pore structure of the supercapacitor maintains a regular shape, and the surface has a well-developed multi-level pore structure, which is the morphological basis for obtaining excellent performance.

[0123] Example 2 increased the elasticity of the binder system by increasing the proportion of SBR in the binder. Its tap density and specific capacitance were slightly improved, and the capacity retention rate increased to 85%. This indicates that a more elastic binder is beneficial for buffering the stress on particles during compression and charge / discharge processes, maintaining the stability of the conductive network and pore structure, thereby improving rate performance and cycle life.

[0124] Example 3, by increasing the ultrasonic atomization intensity, yielded spherical precursor droplets with finer particle size and more uniform distribution. This improvement essentially provides a more uniform and refined initial structural template. Under consistent pre-activation and etching conditions, smaller starting units facilitate the formation of an integrated three-dimensional network with a more concentrated pore size distribution and better connectivity. Therefore, the specific surface area and mesoporosity of the product are further improved, resulting in enhanced electrochemical performance. This demonstrates that optimizing ultrasonic atomization parameters is an effective front-end method for precisely controlling the microstructure of the final electrode material.

[0125] Example 4 uses a lower pre-activation temperature, and the performance indicators are slightly lower than those of Example 1, but are still significantly better than the comparative example.

[0126] Example 5 employed CO2 etching at a higher temperature and for a longer duration, resulting in an extremely high specific surface area and the highest single-point specific capacitance; however, rate performance did not increase proportionally. This indicates that while excessive etching creates a large number of micropores, it may lead to decreased connectivity of some channels or slight collapse of the carbon framework, thus affecting rapid ion transport at high rates.

[0127] Example 6 achieved one of the best overall performance results by increasing the proportion of graphene oxide to 20%, particularly with a capacity retention rate as high as 87%. This strongly demonstrates the irreplaceable and crucial role of secondary carbon sources (bridging conductive agents) in constructing efficient three-dimensional conductive networks and reducing the overall impedance of electrodes.

[0128] Example 7, using a lower slurry solids content, achieved performance comparable to Example 1. This indicates that the method has a certain degree of adaptability to slurry viscosity, and lower viscosity helps to atomize and form particles with higher sphericity.

[0129] Example 8 combines the advantages of high-elasticity binder, high-strength atomization, and high-temperature etching, achieving the best overall performance among all examples (tap density 0.81 g / cm³). 3With a specific capacitance of 210F / g and a capacitance retention rate of 89%, it demonstrates the positive synergistic effect among the various optimized parameters.

[0130] Comparative Example 1 did not use ultrasonic atomization, but instead used conventional spray drying. The resulting carbon skeleton had an irregular pore morphology, leading to a sharp drop in tap density to 0.58 g / cm³. 3 The electrochemical performance deteriorated significantly. This directly proves that ultrasonic atomization to form regular spherical particles is a necessary prerequisite for obtaining high tap density and regular secondary pores.

[0131] Comparative Example 2, without the addition of a secondary carbon source (graphene oxide), achieved a certain tap density (0.65 g / cm³) through spheroidization. 3 However, its specific capacitance, especially its capacity retention (72%), was significantly lower than that of Example 1. This confirms that the introduction of a bridging conductive agent is crucial for constructing a long-range three-dimensional conductive network and achieving excellent rate performance.

[0132] Comparative Example 3, using an oil-based PVDF / NMP binder system, showed performance that was significantly lower than that of Example 1, which used a water-based CMC / SBR system. This indicates that the specific water-based composite binder system is not only environmentally friendly, but also exhibits superior compatibility with the slurry components and contributes better to the formation and structure retention of spherical particles compared to the traditional oil-based system.

[0133] Comparative Examples 4 and 5 illustrate the consequences of under-etching and over-etching, respectively. Under-etching (700℃) results in insufficient specific surface area and porosity development, fewer active sites, and poor performance. Over-etching (1000℃), while not resulting in a low specific surface area, may lead to deterioration in tap density and electrochemical performance due to carbon framework sintering. This clarifies that the CO2 etching step must be carried out within a suitable temperature window of 800-950℃ to achieve the optimal balance between creating abundant active channels and maintaining structural strength.

[0134] Comparative Example 6 demonstrates the necessity of this step from the opposite perspective. When activated carbon without pre-activation is directly etched at high temperatures, the internal binder and volatiles decompose violently, leading to the collapse of the particle structure. Consequently, its tap density, specific surface area, and electrochemical performance are expected to be significantly lower than in Example 1. This fully demonstrates that low-temperature pre-activation is an indispensable step for the precursor to achieve a smooth transition, complete structural reconstruction and initial network connections, thereby creating a stable foundation for subsequent controllable etching.

[0135] In summary, this invention successfully prepared a supercapacitor electrode with high tap density, high specific capacity, and excellent rate performance by combining ultrasonic atomization granulation, synergistic use of water-based composite binder and bridging conductive agent, and a two-step heat treatment process. The comparative examples demonstrate from the opposite perspective that the above-mentioned technical features are indispensable and bring about significant technical effects.

[0136] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for preparing supercapacitor carbon by ultrasonic atomization, characterized in that, Includes the following steps: (1) The carbonized powder, bridging conductive agent, and binder solution are dispersed in a solvent at a mass ratio of (80-95):(5-20):(2-10) to form a mixed slurry, wherein the solid content of the mixed slurry is 10-30 wt%. (2) In an ultrasonic atomizing device, the mixed slurry is ultrasonically atomized to form droplets with a particle size of 20-100 μm, and dried and solidified at 150-300℃ under an inert atmosphere to obtain precursor particles; (3) The precursor particles are heated to 300-500℃ at 2-8℃ / min under an inert atmosphere and pre-activated at low temperature for 1-3 hours to obtain pre-activated activated carbon. (4) The pre-activated carbon is heated to 800-950℃ in a CO2 atmosphere at 5-10℃ / min and etched for 1-4 hours to obtain supercapacitor carbon; The adhesive solution is a composite aqueous solution of sodium carboxymethyl cellulose and styrene-butadiene rubber.

2. The method according to claim 1, characterized in that, The bridging conductive agent is graphene oxide and / or carbon nanotubes.

3. The method according to claim 1, characterized in that, The mass ratio of sodium carboxymethyl cellulose to styrene-butadiene rubber in the adhesive solution is 1.5:1 to 1:

2.

4. The method according to claim 1, characterized in that, In step (1), the pH value of the adhesive solution is 8-10.

5. The method according to claim 1, characterized in that, In step (2), the parameters set for the ultrasonic atomizing device are: frequency of 20-100kHz and power density of 0.5-3.0W / cm². 2 The atomization rate is 0.1-5.0 L / h; And / or, in step (4), the CO2 gas flow rate is 50-200 mL / min And / or, in step (3), the low-temperature pre-activation temperature is 350-450°C.

6. A supercapacitor carbon, characterized in that, It is prepared by the method for preparing supercapacitor carbon by ultrasonic atomization according to any one of claims 1-5, wherein the specific surface area of ​​the supercapacitor carbon is 1500-2500 m². 2 / g, wherein the mesoporosity is 40%-55% in the pore size range of 2-50nm.

7. A method for preparing a supercapacitor electrode, characterized in that, Includes the following steps: The supercapacitor carbon as described in claim 6 is prepared by mixing it with a conductive agent and a reinforcing binder, and then pressing it into shape.

8. The method according to claim 7, characterized in that: The conductive agent is a carbon black material, including one or two of acetylene black or super conductive carbon black; And / or, the reinforcing adhesive is a polytetrafluoroethylene emulsion or a composite aqueous solution of sodium carboxymethyl cellulose and styrene-butadiene rubber; And / or, the pressure of the compression molding is 5-20 MPa.

9. A supercapacitor electrode, characterized in that, It is prepared by the method for preparing supercapacitor electrodes as described in any one of claims 7-8.

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