Composite electrode material with high cycle stability, preparation method and supercapacitor

Abstract

A composite electrode material with high cycle stability comprises a carbonized Chinese fir carrier containing a tracheid structure, needle-like MnO2 and PEDOT: PSS, the needle-like MnO2 grows on the tracheid structure of the carbonized Chinese fir through a hydrothermal reaction, and the PEDOT: PSS is loaded on the carbonized Chinese fir and the needle-like MnO2; and an antioxidant is grafted on the PEDOT: PSS. According to the preparation method disclosed by the invention, a carbonized Chinese fir carrier is subjected to potassium permanganate hydrothermal treatment to grow manganese dioxide, and vacuum impregnation of a PEDOT: PSS solution is carried out, so that the MnO2 / PEDOT: PSS carbonized wood composite material with optimal performance is prepared. Further combining the material with an antioxidant; under the current density of 1mA / cm, the composite material realizes the high specific capacitance of 8.94 F / cm, and still keeps the capacity retention rate of 98.54% after 2000 charge-discharge cycles under the current density of 20mA / cm.

Description

Technical Field

[0001] This invention relates to an electrode material, and more particularly to a composite electrode material with high cycle stability, a preparation method thereof, and a supercapacitor. Background Technology

[0002] With the increasing demand for energy and the growing awareness of sustainable development, bio-based materials are being widely used in the field of supercapacitors due to their green and environmentally friendly characteristics and abundant resources. Among them, wood, with its natural porous structure, can effectively shorten ion diffusion paths and improve electrochemical performance, but it also has drawbacks such as low specific capacity and poor cycle stability.

[0003] Manganese dioxide (MnO2), with its pseudocapacitive properties, can enhance the specific capacitance of electrodes. It is typically loaded onto the surface of conductive substrates (such as carbon paper, carbon fiber, or wood) via electrochemical deposition or hydrothermal methods to form porous structures. For example, carbon paper, due to its high specific surface area and conductivity, is widely used to support MnO2 nanoparticles, forming embedded composite electrodes. However, the poor conductivity and large volume changes of MnO2, which can lead to structural instability, limit its application effectiveness.

[0004] To address the poor conductivity of MnO2, patent CN110085433A describes the preparation of carbon nanotubes on the inner wall of cedar tracheids using chemical vapor deposition (CVD). The loading of carbon nanotubes enhances the conductivity of the electrode. However, the timing of carbon nanotube formation on AWC sheets is extremely critical. Different CVD deposition methods result in carbon nanotubes with different morphologies within the AWC tracheid structure. For example, a CVD time of 7 minutes results in oriented carbon nanotubes. However, the hydrophobic nature of these oriented carbon nanotubes means that even with hydrophilic treatment, they cannot meet the requirements for electrochemical deposition in manganese acetate and sodium sulfate solutions. In other words, depositing manganese dioxide on the surface of oriented carbon nanotubes is challenging, and even if manganese dioxide is deposited, its quality is poor.

[0005] Natural materials such as wood require carbonization to improve conductivity, but high-temperature treatment may damage their porous structure and reduce the loading of active materials. Conductive polymers can cover the surface of wood pores, forming continuous electron transport paths and reducing interfacial resistance. Currently, there are three methods for conductive polymer composites: 1. In-situ polymerization: Wood is immersed in a solution of conductive monomers (such as aniline and pyrrole), and polymerization is initiated by an oxidant (such as FeCl3 or APS) to form a uniform coating layer. Wood / PPy composite electrodes achieve an areal capacitance of 0.61 F / cm². 2(1 mV / S). However, its reaction conditions are harsh and its controllability is poor, making large-scale production difficult. 2. Electrochemical deposition: Conductive polymers are electrochemically deposited on the surface of wood, with precise control over thickness and morphology (such as nanowires and nanosheets). This method involves complex equipment and processes, and the deposition rate is slow, making it difficult to meet the needs of large-scale continuous production. 3. Vacuum impregnation: A conductive polymer solution (such as PEDOT:PSS) is impregnated into the pores of wood, and after drying, a continuous conductive film is formed. The process is simple and suitable for large-scale production.

[0006] In existing mature supercapacitor assembly processes, PEDOT:PSS is exposed to air for extended periods and absorbs moisture. During use, leakage current oxidizes this moisture, producing oxygen. PEDOT:PSS reacts with this oxygen, causing it to oxidize and break down, detaching from the anode surface. This reduces the stability and capacitance of the PEDOT:PSS, severely limiting device performance and potentially leading to failure. Therefore, improving the oxidation resistance of the PEDOT:PSS system is crucial for extending capacitor lifespan and enhancing the long-term stability of related electronic devices. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a composite electrode material with high cycle stability, a preparation method and a supercapacitor.

[0008] To solve the above-mentioned technical problems, the technical solution proposed by the present invention is as follows: a composite electrode material with high cycle stability, comprising a carbonized fir carrier containing a tracheid structure, needle-like MnO2, and PEDOT:PSS, wherein needle-like MnO2 is grown on the tracheid structure of the carbonized fir through a hydrothermal reaction, and PEDOT:PSS is loaded on the carbonized fir and the needle-like MnO2; an antioxidant is grafted onto the PEDOT:PSS.

[0009] In the aforementioned composite electrode material with high cycle stability, preferably, the antioxidant includes one or more of butylated hydroxyanisole, butylated hydroxytoluene, and tert-butylhydroquinone.

[0010] Preferably, in the above-mentioned composite electrode material with high cycle stability, the carbonized cedar wood carrier is carbonized cedar wood chips or carbonized cedar wood particles.

[0011] A method for preparing a composite electrode material with high cycle stability includes the following steps: 1) Preparation of carbonized cedar wood carrier; 2) Growth of needle-like MnO2; The carbonized fir wood carrier prepared in step 1) was placed together with a potassium permanganate solution with a concentration of 0.025M to 0.030M in a hydrothermal reactor and reacted for 10-15 hours at a temperature between 120℃ and 150℃. After the hydrothermal reaction was completed, the carbonized fir wood carrier was cleaned and then dried to obtain a carbonized fir wood carrier with MnO2 nanosheets grown on it. 3) PEDOT: The load of PSS; ① The carbonized fir support with MnO2 nanosheets prepared in step 2) is immersed in a PEDOT:PSS impregnation solution for 20 to 30 minutes under vacuum; the weight concentration of PEDOT:PSS in the PEDOT:PSS impregnation solution is 0.5%-3%; ② Dry the carbonized cedar wood carrier obtained in step ① at a temperature of 60℃ to 80℃ for 6 to 8 hours; 4) Immerse the carbonized cedar wood carrier obtained in step 3) in an antioxidant solution and allow the wood chips to soak in a vacuum environment for 40 to 50 minutes; after removal, dry at a temperature of 60°C to 80°C for 6 to 8 hours; the antioxidant solution includes one or more of butylated hydroxyanisole solution, butylated hydroxytoluene solution and tert-butylhydroquinone solution.

[0012] In the above-mentioned method for preparing composite electrode materials with high cycle stability, preferably, the solvent of the antioxidant solution in step 4) includes water and ethanol, and the volume ratio of water to ethanol is 1:1-1:2.

[0013] In the preferred method for preparing the composite electrode material with high cycle stability described above, in step 3), the carbonized fir wood carrier is repeatedly impregnated in the impregnation solution of PEDOT:PSS 2-5 times; the surface of the carbonized fir wood carrier that has completed the previous impregnation needs to be dried before the last impregnation.

[0014] In the preferred method for preparing the composite electrode material with high cycle stability described above, in step 4), the carbonized fir wood carrier is repeatedly impregnated in an antioxidant solution 2-5 times; the surface of the carbonized fir wood carrier that has completed the previous impregnation needs to be dried before the next impregnation.

[0015] The preparation method of the above-mentioned composite electrode material with high cycle stability, preferably, includes the following steps in step 1) of preparing the carbonized fir wood carrier; I. Cut the cedar wood into thin slices or granules of a predetermined size along the direction perpendicular to the tracheids; II. The fir wood chips or fir wood particles from step I are pre-carbonized at a temperature of 200°C to 250°C for 6-8 hours. III. The pre-carbonized fir wood chips or fir wood particles are carbonized at a high temperature of 750°C to 1000°C for 5 to 7 hours in an argon atmosphere to complete the carbonization. IV involves activating carbonized cedar chips or granules in a carbon dioxide environment at 750°C to 800°C for 9 to 10 hours to obtain a carbonized cedar carrier.

[0016] A supercapacitor comprising the aforementioned composite electrode material with high cycle stability.

[0017] Compared with existing technologies, the advantages of this invention are as follows: In this invention, carbonized fir wood carrier undergoes hydrothermal treatment with potassium permanganate to grow manganese dioxide, followed by vacuum impregnation with PEDOT:PSS solution to prepare a high-performance MnO2 / PEDOT:PSS@carbonized wood composite material. Furthermore, this material is combined with an antioxidant; at a current density of 1 mA / cm², this composite material achieves a high specific capacitance of 8.94 F / cm², and after 2000 charge-discharge cycles at 20 mA / cm², it still retains 98.54% of its capacity. Attached Figure Description

[0018] Figure 1 The CV curves of the MnO2 / 3%PEDOT:PSS@carbonized wood electrode material at different scan rates are shown.

[0019] Figure 2 GCD curves of MnO2 / 3%PEDOT:PSS@carbonized wood electrode material at different current densities.

[0020] Figure 3 The CV curves of the MnO2 / 1%PEDOT:PSS@carbonized wood electrode material at different scan rates are shown.

[0021] Figure 4 GCD curves of MnO2 / 1%PEDOT:PSS@carbonized wood electrode material at different current densities.

[0022] Figure 5 Impedance diagrams for the electrode materials of carbonized wood / MnO2, MnO2 / 3%PEDOT:PSS@carbonized wood, and MnO2 / 1%PEDOT:PSS@carbonized wood.

[0023] Figure 6 The CV curves of the MnO2 / 1%PEDOT:PSS / BHA@carbonized wood electrode material at different scan rates are shown.

[0024] Figure 7 GCD curves of MnO2 / 1%PEDOT:PSS / BHA@carbonized wood electrode material at different current densities.

[0025] Figure 8The CV curves of the MnO2 / 1%PEDOT:PSS / BHT@carbonized wood electrode material at different scan rates are shown.

[0026] Figure 9 GCD curves of MnO2 / 1%PEDOT:PSS / BHT@carbonized wood electrode material at different current densities.

[0027] Figure 10 The CV curves of the MnO2 / 1%PEDOT:PSS / TBHQ@carbonized wood electrode material at different scan rates are shown.

[0028] Figure 11 GCD curves of MnO2 / 1%PEDOT:PSS / TBHQ@carbonized wood electrode material at different current densities.

[0029] Figure 12 EIS diagram of MnO2 / PEDOT:PSS@carbonized wood electrode material combined with three antioxidants.

[0030] Figure 13 20mA / cm 2 Cycle life diagram of MnO2 / 1%PEDOT:PSS / BHA@carbonized wood electrode material at current density.

[0031] Figure 14 20mA / cm 2 Cycle life diagram of MnO2 / 1%PEDOT:PSS / BHT@carbonized wood electrode material at current density.

[0032] Figure 15 20mA / cm 2 Cycle life diagram of MnO2 / 1%PEDOT:PSS / TBHQ@carbonized wood electrode material at current density.

[0033] Figure 16 20mA / cm 2 The overall cycle life of electrode materials grafted with three antioxidants at current densities. Detailed Implementation

[0034] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0035] It should be noted that when a component is described as being "fixed to, attached to, connected to or connected to" another component, it can be directly fixed to, attached to, connected to or connected to the other component, or it can be indirectly fixed to, attached to, connected to or connected to the other component through other intermediate connectors.

[0036] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention. Example 1

[0037] This embodiment provides a composite electrode material with high cycle stability, comprising a carbonized fir support containing tracheid structures, needle-like MnO2, and PEDOT:PSS. Needle-like MnO2 is grown on the tracheid structures of the carbonized fir through a hydrothermal reaction. PEDOT:PSS is loaded onto the carbonized fir and needle-like MnO2. An antioxidant, tert-butylhydroquinone, is grafted onto the PEDOT:PSS. In this embodiment, the antioxidant can also be butylated hydroxyanisole (BHA) or butylated hydroxytoluene (BHT).

[0038] In this embodiment, the carbonized cedar wood carrier is a carbonized cedar wood chip, with a length of approximately 50 to 70 mm, a width of 20 to 40 mm, and a thickness of 0.5 to 1 mm. In other embodiments, when the carbonized cedar wood carrier is carbonized cedar wood particles, the particle size is less than 1 mm. In this embodiment, when the carbonized cedar wood carrier is a carbonized cedar wood chip, the resulting composite electrode material can be used directly as an electrode; when the carbonized cedar wood carrier is a carbonized cedar wood particle, the resulting composite electrode material needs to be used in conjunction with a current collector.

[0039] This embodiment also provides a method for preparing a composite electrode material with high cycle stability. 1) Preparation of carbonized cedar wood carrier; The pond cypress wood is cut into thin slices perpendicular to the tracheids, approximately 50 to 70 mm in length, 20 to 40 mm in width, and 2 to 3 mm in thickness. First, it undergoes pre-carbonization in an electrically heated constant-temperature drying oven at 200 to 250 degrees Celsius for 6 to 7 hours. Next, it undergoes carbonization activation treatment, carbonizing at 750 to 1000 degrees Celsius in an argon atmosphere for 5 to 7 hours, followed by activation treatment in a carbon dioxide environment at 750 to 800 degrees Celsius for 9 to 10 hours, ultimately producing activated wood carbon flakes. The wood flakes are then sanded using 500 to 1200 grit sandpaper until they reach a thickness of 0.5 to 1 mm. Because of the sanding, the wood flakes are finally cleaned with deionized water in an ultrasonic cleaner until the water becomes clear, and then dried overnight in an electrically heated constant-temperature drying oven at 60 to 80 degrees Celsius.

[0040] 2) Growth of needle-like MnO2; The carbonized fir wood carrier prepared in step 1) was placed together with a potassium permanganate solution with a concentration of 0.025 mol / L to 0.030 mol / L in a hydrothermal reactor and reacted for 10-15 hours at a temperature between 120℃ and 150℃. After the hydrothermal reaction was completed, the carbonized fir wood carrier was cleaned and then dried to obtain a carbonized fir wood carrier with MnO2 nanosheets grown on it. The specific steps for cleaning and drying were as follows: the hydrothermally heated wood chips were cleaned three times in deionized water in an ultrasonic cleaner, each time for 5 to 10 minutes, and then placed in a drying oven at 60 to 80℃ for more than 8 hours to obtain carbonized wood / MnO2 material.

[0041] 3) PEDOT: The load of PSS; ① The carbonized fir support with MnO2 nanosheets prepared in step 2) is immersed in a PEDOT:PSS impregnation solution for 20 to 30 minutes under vacuum. The weight concentration of PEDOT:PSS in the impregnation solution is 0.5%-3%. In this embodiment, the solvent of the PEDOT:PSS impregnation solution is water, and dimethyl methacrylate (DMSO) is added to the PEDOT:PSS impregnation solution. After mixing with PEDOT:PSS, DMSO can weaken the Coulomb interaction between charge carriers in the PEDOT chains and PSS anions. In the PEDOT:PSS aqueous solution, PSS will encapsulate the PEDOT chains to form an insulating aggregate structure. As a strongly polar solvent, DMSO can destroy the hydrogen bonding between PSS and PEDOT, promoting the PEDOT chains to unfold and rearrange into a conductive network. It can also effectively enhance the crystallinity of the material, thereby improving its conductivity. The carbonized cedar wood carrier is repeatedly impregnated in the PEDOT:PSS impregnation solution 2-5 times; the surface of the carbonized cedar wood carrier after the previous impregnation needs to be dried before the next impregnation.

[0042] ② Dry the carbonized cedar wood carrier obtained in step ① at a temperature of 60℃ to 80℃ for 6 to 8 hours.

[0043] Figure 1 The CV curves of the MnO2 / 3%PEDOT:PSS@carbonized wood electrode material at different scan rates are shown.

[0044] Figure 2 GCD curves of MnO2 / 3%PEDOT:PSS@carbonized wood electrode material at different current densities.

[0045] Figure 3 The CV curves of the MnO2 / 1%PEDOT:PSS@carbonized wood electrode material at different scan rates are shown.

[0046] Figure 4GCD curves of MnO2 / 1%PEDOT:PSS@carbonized wood electrode material at different current densities.

[0047] The carbonized cedar wood carrier obtained in step 3) is immersed in an antioxidant solution, and the wood chips are impregnated under vacuum for 40 to 50 minutes. After removal, it is dried at 60°C to 80°C for 6 to 8 hours. The antioxidant solution consists of water and ethanol in a volume ratio of 1:1 to 1:2. The carbonized cedar wood carrier is repeatedly impregnated in the antioxidant solution 2 to 5 times. Before each subsequent impregnation, the surface of the carbonized cedar wood carrier after the previous impregnation needs to be dried. This yields the MnO2 / PEDOT:PSS / TBHQ@carbonized wood electrode material.

[0048] Figure 5 Impedance diagrams for the electrode materials of carbonized wood / MnO2, MnO2 / 3%PEDOT:PSS@carbonized wood, and MnO2 / 1%PEDOT:PSS@carbonized wood.

[0049] In this embodiment, the antioxidant is tert-butylhydroquinone solution; in other embodiments, butylated hydroxyanisole solution or butylated hydroxytoluene solution can be used, but their effects are not as good as tert-butylhydroquinone solution.

[0050] In this embodiment, carbonized wood is used as the electrode material substrate. Carbonized wood is produced by high-temperature carbonization of biomass wood, which is widely available and generates fewer pollutants during the carbonization process. Furthermore, the preparation of the carbonized wood substrate aligns with green chemistry principles, is environmentally friendly, and contributes to sustainable development. Compared to traditional metal (such as platinum and titanium) or high-valent carbon materials (such as graphene and carbon nanotubes) substrates, carbonized wood significantly reduces costs, greatly minimizing the economic investment in electrode material preparation. The unique porous structure of carbonized wood provides abundant surface area and three-dimensional space for the subsequent loading of MnO2 and PEDOT:PSS, which is beneficial for the uniform distribution of MnO2 and PEDOT:PSS.

[0051] In this invention, the performance of the MnO2 / PEDOT:PSS / TBHQ@carbonized wood electrode material was tested using an electrochemical workstation with a platinum electrode as the counter electrode, an Ag / AgCl electrode as the reference electrode, and a 2 mol / L Na2SO4 aqueous solution as the electrolyte. To fabricate a symmetrical all-solid-state supercapacitor, a non-woven fabric membrane was used as the separator, and the MnO2 / PEDOT:PSS / TBHQ@carbonized wood electrode material was assembled as both the cathode and anode. 1 g of polyvinyl alcohol was mixed with 10 mL of DI water and heated to 90°C, stirred for 2 hours, and then cooled to room temperature. Finally, 1 g of Na2SO4 was added and stirred until homogeneous to obtain a sodium polyvinyl sulfate gel electrolyte. The cathode, anode, and non-woven fabric membrane were immersed in the sodium polyvinyl sulfate gel electrolyte and then dried to obtain the all-solid-state supercapacitor. Its electrochemical performance was then tested using an electrochemical workstation.

[0052] All tests were conducted on the Shanghai Chenhua CHI660E electrochemical workstation, which can simultaneously connect to the working electrode, counter electrode, and reference electrode to form a three-electrode system. It can precisely control the reaction potential and supports cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), etc., and is suitable for the electrochemical performance testing of different materials.

[0053] The supercapacitor was assembled using a "sandwich" structure, sandwiching two electrodes between a membrane, coating with sodium polyvinyl sulfate gel electrolyte, gently pressing to remove air bubbles, and drying before testing. The operating voltage window of the MnO2 / PEDOT:PSS / TBHQ@carbonized wood electrode is -0.2~0.8 V, therefore the operating voltage range of the symmetrical supercapacitor was set to 0-1.0 V. At 1 mA / cm²... 2 The constant current charge-discharge curves at the specified current density exhibit an approximately symmetrical triangular shape, indicating that the surface capacitance density of this symmetrical supercapacitor is 4.47 F / cm². 2 At 2.82mW / cm 2 It exhibits a high power density of 148 μWh / cm³. 2 The energy density is 20 mA / cm². 2 It retains 85.46% of its capacitance after 2000 cycles at current density.

[0054] MnO2 possesses a high theoretical specific capacitance. MnO2 grown via hydrothermal methods exhibits a needle-like three-dimensional mesh structure, which significantly increases the specific surface area of ​​the electrode material and provides more active sites. After growing manganese dioxide on the surface of carbonized wood substrates using a potassium permanganate hydrothermal method, the specific capacitance is 1 mA / cm². 2 At a current density of 5.58 F / cm, the electrode specific capacitance reaches 5.58 F / cm.2 Further impregnation with PEDOT:PSS significantly improved the specific capacitance of the electrode material, increasing by 15.60% to 6.45 F / cm compared to the electrode with only MnO2 growth. 2 This is because PEDOT:PSS, as a conductive polymer, with its unique conjugated structure, can form a continuous network structure with MnO2, encapsulating the MnO2 layer and deeply filling the pores of the carbonized wood structure. This creates a more efficient and continuous electron transport network, significantly reducing the electrode's internal resistance and accelerating charge transfer during charging and discharging. PEDOT:PSS also prevents MnO2 from detaching, improving the electrochemical performance of the carbonized wood / MnO2 material. However, when the concentration is too high, such as 3 wt% PEDOT:PSS, the particle concentration in the electrode material is too high, causing a large number of particles to block the pores of the wood tracheids. As an important porous structure in carbonized wood, the blockage of the pores of wood tracheids severely hinders the diffusion and transport of electrolyte ions, leading to a decrease in electrode performance and a narrowing of the voltage window range. As the concentration gradually decreases, the electrode specific capacitance increases. This is because an appropriate concentration of PEDOT:PSS can enter and fully fill the pores of the carbonized wood / MnO2 composite structure, further optimizing the electron transport path and enhancing the contact between the active material and the electrolyte, thereby increasing the specific capacitance. Therefore, there exists an optimal concentration of 1 wt% that allows the electrochemical performance of the electrode material to reach its best.

[0055] The high specific surface area and porous structure of carbonized wood provide a uniformly dispersed carrier for MnO2 and PEDOT:PSS, while simultaneously enhancing the loading of antioxidants through physical adsorption. This results in a physicochemical synergistic effect between MnO2, PEDOT:PSS, and antioxidants in the electrode material. The antioxidants are embedded in the pores, forming close contact with the substrate, reducing the exposure of active sites, delaying oxidation reactions, and extending cycle life.

[0056] Electrode materials prepared using butylated hydroxyanisole (BHA) antioxidants achieved an efficiency of 1 mA / cm². 2 At a current density of 7.16 F / cm, the electrode specific capacitance reaches 7.16 F / cm. 2 Compared to the MnO2 / 1%PEDOT:PSS@carbonized wood electrode material, the specific capacity was improved by 11.01%. This is because the hydroxyl structure of BHA can chelate metal ions on the MnO2 surface and scavenge free radicals, enhancing the synergistic effect of antioxidant activity. BHA can also compensate for surface defects of PEDOT:PSS through hydrogen bonding and π-π stacking, thereby extending cycle life. Tests showed that the MnO2 / PEDOT:PSS / BHA@carbonized wood electrode material achieved a specific capacity of 20 mA / cm². 2 After 2000 cycles, the capacity retention rate reached 95.77%.

[0057] Figure 6 The CV curves of the MnO2 / 1%PEDOT:PSS / BHA@carbonized wood electrode material at different scan rates are shown.

[0058] Figure 7 GCD curves of MnO2 / 1%PEDOT:PSS / BHA@carbonized wood electrode material at different current densities.

[0059] Figure 13 20mA / cm 2 Cycle life diagram of MnO2 / 1%PEDOT:PSS / BHA@carbonized wood electrode material at current density.

[0060] Electrode materials prepared using butylated hydroxytoluene (BHT) antioxidants achieved a current of 1 mA / cm. 2 At a current density of 8.85 F / cm, the electrode specific capacitance reaches 8.85 F / cm. 2 Compared to the MnO2 / 1%PEDOT:PSS@carbonized wood electrode material, the specific capacity is improved by 37.2%. During the charge and discharge process of this material, BHT has the ability to rapidly transfer electrons, which can neutralize the free radicals generated by the oxidizing active material MnO2 during cycling. At the same time, the hydroxyl structure connects with the PEDOT:PSS chain to form a large number of hydrogen bond network structures, repairing the conductive pathways broken by oxidation. This creates a dynamic balance between the oxidizing capacity of MnO2 and the reducing capacity of the antioxidant, inhibiting the overall oxidative degradation of the material, slowing down the decay of conductivity, and thus extending the cycle life. Tests show that the MnO2 / PEDOT:PSS / BHT@carbonized wood electrode material achieves a specific capacity of 20 mA / cm². 2 After 2000 cycles, the capacity retention rate reached 97.74%.

[0061] Figure 8 The CV curves of the MnO2 / 1%PEDOT:PSS / BHT@carbonized wood electrode material at different scan rates are shown.

[0062] Figure 9 GCD curves of MnO2 / 1%PEDOT:PSS / BHT@carbonized wood electrode material at different current densities.

[0063] Figure 14 20mA / cm 2 Cycle life diagram of MnO2 / 1%PEDOT:PSS / BHT@carbonized wood electrode material at current density.

[0064] Electrode materials prepared using tert-butylhydroquinone (TBHQ) antioxidants achieved an efficiency of 1 mA / cm². 2 At a current density of 8.94 F / cm, the electrode specific capacitance reaches 8.94 F / cm.2 Compared to the MnO2 / 1%PEDOT:PSS@carbonized wood electrode material, the specific capacity is improved by 38.6%. In the TBHQ structure, the steric hindrance of the tert-butyl group hinders the attack of free radicals, and the phenolic hydroxyl group coordinates with metal ions, reducing manganese ion dissolution and material degradation. The synergistic effect of TBHQ and PEDOT:PSS can repair the broken conductive network, reduce resistivity, and protect the MnO2 layer from peeling off, greatly improving the cycle life of the electrode material. After testing, the MnO2 / 1%PEDOT:PSS / TBHQ@carbonized wood electrode material exhibits a capacity of 20 mA / cm². 2 After 2000 cycles, the capacity retention rate reached 98.54%. Figure 10 The CV curves of the MnO2 / 1%PEDOT:PSS / TBHQ@carbonized wood electrode material at different scan rates are shown.

[0065] Figure 11 GCD curves of MnO2 / 1%PEDOT:PSS / TBHQ@carbonized wood electrode material at different current densities.

[0066] Figure 15 20mA / cm 2 Cycle life diagram of MnO2 / 1%PEDOT:PSS / TBHQ@carbonized wood electrode material at current density.

[0067] Figure 12 EIS diagram of MnO2 / PEDOT:PSS@carbonized wood electrode material combined with three antioxidants.

[0068] Figure 16 20mA / cm 2 The overall cycle life of electrode materials grafted with three antioxidants at current densities.

[0069] The loading of PEDOT:PSS and antioxidants can be completed simply by immersing the carbonized wood / MnO2 composite electrode in a solution. The process is simple, convenient, and requires no expensive or complex equipment, greatly improving production efficiency. Meanwhile, PEDOT:PSS material is inexpensive, and hindered phenolic antioxidants are non-discoloring, non-polluting, and low-toxic or non-toxic, making them the most widely produced and marketed high-efficiency antioxidants. This achieves a triple improvement in environmental friendliness, economic benefits, and production efficiency, demonstrating enormous potential for industrialization and paving the way for future research into the potential applications of antioxidants in the protection of electrode materials for new energy materials.

Claims

1. A composite electrode material with high cycle stability, characterized in that: The invention comprises a carbonized fir carrier containing tracheid structures, needle-like MnO2, and PEDOT:PSS. Needle-like MnO2 grows on the tracheid structures of the carbonized fir through a hydrothermal reaction, and PEDOT:PSS is loaded on the carbonized fir and needle-like MnO2. An antioxidant is grafted onto the PEDOT:PSS.

2. The composite electrode material with high cycle stability according to claim 1, characterized in that: The antioxidants include one or more of butylated hydroxyanisole, butylated hydroxytoluene, and tert-butylhydroquinone.

3. The composite electrode material with high cycle stability according to claim 1, characterized in that: The carbonized fir wood carrier is carbonized fir wood chips.

4. A method for preparing a composite electrode material with high cycle stability, characterized in that: Includes the following steps, 1) Preparation of carbonized cedar wood carrier; 2) Growth of needle-like MnO2; The carbonized fir wood carrier prepared in step 1) was placed together with a potassium permanganate solution with a concentration of 0.025M to 0.030M in a hydrothermal reactor and reacted for 10-15 hours at a temperature between 120℃ and 150℃. After the hydrothermal reaction was completed, the carbonized fir wood carrier was cleaned and then dried to obtain a carbonized fir wood carrier with MnO2 nanosheets grown on it. 3) PEDOT: The load of PSS; ① The carbonized fir support with MnO2 nanosheets prepared in step 2) is immersed in a PEDOT:PSS impregnation solution for 20 to 30 minutes under vacuum; the weight concentration of PEDOT:PSS in the PEDOT:PSS impregnation solution is 0.5%-3%; ② The carbonized cedar wood carrier obtained in step ③① is dried at a temperature of 60℃ to 80℃ for 6 to 8 hours; 4) Immerse the carbonized cedar wood carrier obtained in step 3) in an antioxidant solution and allow the wood chips to soak in a vacuum environment for 40 to 50 minutes; after removal, dry at a temperature of 60°C to 80°C for 6 to 8 hours; the antioxidant solution includes one or more of butylated hydroxyanisole solution, butylated hydroxytoluene solution and tert-butylhydroquinone solution.

5. The method for preparing the high-cycle-stability composite electrode material according to claim 4, characterized in that: The solvent for the antioxidant solution in step 4) includes water and ethanol, with a volume ratio of water to ethanol of 1:1 to 1:

2.

6. The method for preparing the composite electrode material with high cycle stability according to claim 4, characterized in that: In step 3), the carbonized cedar wood carrier is repeatedly impregnated in the PEDOT:PSS impregnation solution 2-5 times; the surface of the carbonized cedar wood carrier after the previous impregnation needs to be dried before the next impregnation.

7. The method for preparing the high-cycle-stability composite electrode material according to claim 4, characterized in that: In step 4), the carbonized cedar wood carrier is repeatedly impregnated in the antioxidant solution 2-5 times; the surface of the carbonized cedar wood carrier after the previous impregnation needs to be dried before the last impregnation.

8. The method for preparing the composite electrode material with high cycle stability according to claim 4, characterized in that: Step 1) The preparation of the carbonized fir wood carrier includes the following steps; I. Cut the cedar wood into thin slices or granules of a predetermined size along the direction perpendicular to the tracheids; II. The fir wood chips or fir wood particles from step I are pre-carbonized at a temperature of 200°C to 250°C for 6-8 hours. III. The pre-carbonized fir wood chips or fir wood particles are carbonized at a high temperature of 750°C to 1000°C for 5 to 7 hours in an argon atmosphere to complete the carbonization. IV involves activating carbonized cedar chips or granules in a carbon dioxide environment at 750°C to 800°C for 9 to 10 hours to obtain a carbonized cedar carrier.

9. A supercapacitor, characterized in that: The composite electrode material with high cycle stability as described in any one of claims 1-3.

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