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CN-121983437-A - MnO2KOH (potassium hydroxide) -synergistically-modified biomass-based porous carbon electrode material as well as preparation method and application thereof

CN121983437ACN 121983437 ACN121983437 ACN 121983437ACN-121983437-A

Abstract

The invention discloses a MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material, a preparation method and application thereof, wherein the preparation method of the electrode material comprises the steps of providing biomass powder; mixing biomass powder and manganese dioxide, grinding uniformly to obtain a mixed material, calcining the mixed material in a segmented manner under an inert atmosphere, cooling, washing and drying to obtain a carbonized product, mixing the carbonized product with potassium hydroxide and dissolving the potassium hydroxide in deionized water to obtain a mixed solution, heating the mixed solution in a water bath, drying after the reaction is finished to obtain a dried mixture, calcining the dried mixture, cooling to obtain an activated product, washing the activated product with acid, and washing, drying and sieving the activated product after ultrasonic treatment to obtain the electrode material. The electrode material has high specific surface area, reasonable micropore-mesopore hierarchical structure, excellent specific capacitance and cycle stability, can remarkably improve the electrochemical performance of the super capacitor, and meets the energy storage requirement of medium-low power density.

Inventors

  • YUAN BIZHEN
  • ZHONG JUNTAO
  • FU JIEPENG
  • CHEN ZHIQIANG
  • LI YINJUN
  • DAI MAOLIN
  • LIAO WENHUI
  • TAO MAN
  • WU ZONGYI
  • LI XINYING
  • HE JINRONG

Assignees

  • 珠海科技学院

Dates

Publication Date
20260505
Application Date
20260328

Claims (10)

  1. 1. The preparation method of the MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material is characterized by comprising the following steps of: (1) Providing biomass powder; (2) Mixing biomass powder and manganese dioxide and grinding uniformly to obtain a mixed material; (3) The mixed material is subjected to sectional calcination in inert atmosphere, cooled, washed and dried to obtain carbonized products; (4) Mixing the carbonized product with potassium hydroxide and dissolving in deionized water to obtain a mixed solution, heating the mixed solution in a water bath, and drying after the reaction is finished to obtain a dried mixture; (5) And (3) pickling the activated product, performing ultrasonic treatment, washing, drying and sieving to obtain the MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material.
  2. 2. The preparation method of the MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material according to claim 1 is characterized in that in the step (1), raw materials used for providing biomass powder are one or more of lotus seedpod shells, coconut shells, peanut shells and straws; specifically, the preparation method of the biomass powder comprises the following steps: s1, the raw materials are dried after being made into blocks, and then are crushed and sieved to obtain powder; S2, sequentially carrying out ultrasonic cleaning and decoloring on the powder by using deionized water and absolute ethyl alcohol, and collecting a solid product after centrifugation to obtain biomass powder; in the step S1, the mesh number of the sieving is 40-100 meshes; in the step S2, the ultrasonic washing power is 150-250W, the time is 30 min/time, and the centrifugation condition is that the centrifugation is carried out for 3-5 min at 8000-9000 rpm.
  3. 3. The preparation method of the MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material, which is disclosed in claim 1, is characterized in that in the step (2), the mass ratio of biomass powder to manganese dioxide is 1 (0.2-0.6), and the grinding time is 30min.
  4. 4. The preparation method of the MnO 2 -KOH synergistic modified biomass-based porous carbon electrode material according to claim 1 is characterized in that in the step (3), the condition of segmented calcination is that the temperature is raised to 200-350 ℃ for 30min at a temperature raising rate of 5-10 ℃ per min, then the temperature is raised to 500 ℃ for 0.5-2 h, the flow rate of inert gas is 80-120 sccm, and the drying condition is vacuum drying for 3h at 60 ℃.
  5. 5. The preparation method of the MnO 2 -KOH synergistic modified biomass-based porous carbon electrode material, which is disclosed in claim 1, is characterized in that in the step (4), the mass ratio of carbonized product to potassium hydroxide is 1 (2-3), the condition of heating in a water bath is that heating is carried out in a constant-temperature water bath at 80 ℃ for 10-12 h, the condition of carbonization is that the temperature is raised to 500 ℃ at the temperature rising rate of 5-10 ℃ per minute for 0.5-2 h, the condition of drying is that the temperature is 60-80 ℃ for 12-16 h, and the potassium hydroxide is analytically pure, and the purity is not less than 85%.
  6. 6. The preparation method of the MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material according to claim 1 is characterized in that in the step (5), an activated product is soaked in a 1mol/L hydrochloric acid solution for 30-60 min, then subjected to ultrasonic treatment for 10min at 150-250W, washed to be neutral by deionized water, then dried at 60-80 ℃ for 10-12 h, and sieved by a 100-mesh sieve, so that the MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material is obtained.
  7. 7. A MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material prepared by the method of any one of claims 1-6.
  8. 8. The MnO 2 -KOH synergistic modified biomass-based porous carbon electrode material according to claim 7 is characterized by having a disordered graphite structure, diffraction peaks corresponding to 002 crystal faces and 100 crystal faces respectively appear at 23.5 degrees and 43 degrees, the specific surface area is more than 250-280 m 2 ·g -1 , the micropore specific surface area is 230-227.6m 2 ·g -1 , the total pore volume is 0.143-0.151 cm 3 ·g -1 , the micropore volume is 0.102-0.111 cm 3 ·g -1 , the average pore diameter is 3.63-3.78 nm, and the surface is in a spongy rough structure and contains abundant irregular concave layers and pore channels.
  9. 9. The application of the MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material in preparing a supercapacitor is characterized in that the electrode material is used as a working electrode of the supercapacitor, the preparation method of the working electrode comprises the steps of mixing the electrode material with acetylene black and polytetrafluoroethylene according to a mass ratio of 80:10:10, adding absolute ethyl alcohol, grinding to prepare slurry with the concentration of 40 mg/mL -1 , coating the slurry on a foam nickel current collector, coating the mass of 3.2mg of the biomass-based porous carbon electrode material with the coating area of 1cm 2 ,MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material, vacuum drying at 60 ℃ for 10 hours, and tabletting to prepare the supercapacitor working electrode.
  10. 10. The use according to claim 9, characterized in that the electrolyte of the supercapacitor is a 6mol/L aqueous KOH solution.

Description

MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material, and preparation method and application thereof Technical Field The invention relates to the technical field of supercapacitor electrode materials, in particular to a MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material, and a preparation method and application thereof. Background Along with the increasingly prominent energy crisis and environmental problems, the development of energy storage equipment with high efficiency, environmental protection and low cost becomes a global research hotspot. The super capacitor is used as a novel energy storage device, and has wide application prospect in a plurality of fields by virtue of the advantages of high power density, rapid charge and discharge capability, long cycle life and the like. The electrode material is a core for determining the performance of the super capacitor, wherein the carbon-based material becomes a main stream electrode material of the commercial super capacitor due to the characteristics of large specific surface area, good conductivity, high stability, low cost and the like. Biomass carbon is a renewable porous carbon material, and is paid attention to with the advantages of wide raw material sources, environmental friendliness, rich natural pore structures and the like. The lotus seedpod is used as common biomass waste, the shell of the lotus seedpod mainly comprises cellulose, hemicellulose and lignin, has high carbon content and natural porous structure potential, and is an ideal raw material for preparing biomass carbon electrode materials. However, the directly carbonized lotus-based carbon material has the problems of small specific surface area (only 65.21m 2·g-1), unreasonable pore size distribution (average pore diameter of 2.33 nm), insufficient conductivity and the like, so that the specific capacitance is low (92 F.g -1), and the application requirement of the high-performance supercapacitor is difficult to meet. In the prior art, the modification method of the biomass carbon material mainly comprises single oxidant oxidation, single alkali activation, graphene compounding and the like. For example, china patent application CN2017107714951 discloses a preparation method of a porous graphene-like active carbon material, a product and application thereof, biomass is pretreated by using an oxidant and weak acid under the assistance of water heat, then the porous graphene-like active carbon material is prepared by high-temperature pyrolysis at 400-1700 ℃, although the high specific surface area (1014 m 2·g-1) and the high specific capacitance (340 F.g -1) can be obtained, the oxidant and the weak acid used have strong corrosiveness, the high-temperature pyrolysis energy consumption and the complex process are high, chinese patent application CN2019110859724 discloses a composite carbon material for sea water desalination and a preparation method thereof, the graphene and active carbon composite carbon material for sea water desalination has the improvement performance by filling graphene, but the graphene preparation cost is high, and the application scene is limited to sea water desalination, and China patent application CN2023102497906 discloses a biomass active carbon coated germanate composite material for a battery cathode, but the composite material depends on scarce germanium resources, and has the complex preparation process and high cost. In addition, it is difficult to achieve synergistic effects of specific surface area elevation, pore size optimization and conductivity improvement simultaneously by a single modification means. Single alkali activation can increase the number of pores but the pore size distribution is uneven, and single metal oxide doping can introduce pseudocapacitance but has limited improvement on pore structure. Therefore, the development of the modification method which has the advantages of simple process, low cost and low energy consumption and can synergistically optimize the structure and the performance of the biomass carbon material has great significance for promoting the industrialized application of the biomass carbon-based electrode material. Disclosure of Invention The invention aims to overcome the defects of the prior art, provides a MnO 2 -KOH synergistically modified biomass-based porous carbon electrode material, and a preparation method and application thereof, solves the problems of small specific surface area, unreasonable pore size distribution and poor electrochemical performance of the traditional biomass-based carbon material, and reduces the energy consumption and cost of a modification process. According to the invention, through the synergistic strategy of manganese dioxide etching pore-forming and potassium hydroxide reaming activation, and the combination of a low-temperature carbonization process, the synchronous optimization of the material structure and perfor