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CN-121983435-A - Covalent modification method of high-performance lignin-based electrode material

CN121983435ACN 121983435 ACN121983435 ACN 121983435ACN-121983435-A

Abstract

The invention discloses a covalent modification method of a high-performance lignin-based electrode material, and belongs to the technical field of biomass-based supercapacitors. Specifically, the kraft lignin is dissolved in DMF, and a difunctional reagent is added for stirring reaction. After the reaction is finished, the reaction solution is poured into deionized water dropwise added with hydrochloric acid, and covalent modified lignin is obtained through processes such as reverse precipitation, filtration, drying, heat treatment, activation and the like. The modified lignin is ground and mixed with a conductive agent and a binder, coated on a current collector and dried to obtain the lignin-based electrode. The covalent modification degree of lignin is regulated and controlled by controlling the addition amount of the bifunctional reagent, so that the modified lignin with different thermodynamic properties is obtained, and the aim of regulating and controlling the defect of lignin derived carbon structure is fulfilled. The preparation method is controllable in scale and simple to operate, and the obtained electrode material has fewer defect structures and excellent electrochemical performance, so that a new theory and a new method are provided for the development of the lignin-based electrode material.

Inventors

  • DAI ZHONG
  • LI SHENG
  • CHEN KUAN

Assignees

  • 长沙理工大学

Dates

Publication Date
20260505
Application Date
20260123

Claims (5)

  1. 1. The covalent modification method of the high-performance lignin-based electrode material is characterized by comprising the following steps of: Step 1, adding kraft lignin and DMF into a conical flask, fully stirring until the kraft lignin and DMF are completely dissolved, adding different amounts of difunctional reagents for reaction, finally pouring the reaction solution into a beaker filled with deionized water (dropwise adding HCl) for reverse precipitation, filtering, and freeze-drying to obtain modified lignin; And 2, placing the modified lignin in a tubular furnace, carbonizing in an inert atmosphere, mixing and grinding the carbonized material and the alkali metal compound to obtain a mixture. Placing the mixture into a tubular furnace for activation, washing the mixture by deionized water until the pH value is neutral, and drying the mixture to obtain a lignin-based carbon material; and 3, grinding the lignin-based carbon material, the conductive agent and the binder into slurry in an agate mortar, uniformly coating the slurry on a current collector, and drying to obtain the lignin-based electrode material.
  2. 2. The covalent modification method of the high-performance lignin-based electrode material according to claim 1 is characterized in that in the step 1, the mass of kraft lignin is 1-6 g, the mass of DMF is 5-12 g, the difunctional reagent is any one of adipic acid, isophorone diisocyanate and terephthalic acid, the weight fraction of the difunctional reagent is 0.1-50 wt%, the reaction temperature is 20-80 ℃, and the reaction time is 24-96 h.
  3. 3. The covalent modification method of the high-performance lignin-based electrode material according to claim 1 is characterized in that in the step 2, the alkali metal compound is any one of calcium hydroxide, sodium hydroxide and potassium hydroxide, and the mass ratio of modified lignin to the alkali metal compound is 1:1-4.
  4. 4. The covalent modification method of the high-performance lignin-based electrode material according to claim 1 is characterized in that in the step 2, the inert atmosphere mainly comprises nitrogen, helium and argon, the gas flow rate is 1-20 mL/min, the heating rate is 1-10 ℃/min, the carbonization temperature is 800-1200 ℃, the activation temperature is 600-1000 ℃, and the heat preservation time is 30-180 min.
  5. 5. The covalent modification method of the high-performance lignin-based electrode material according to claim 1 is characterized in that in the step 3, the conductive agent is any one of acetylene black, conductive carbon black and conductive graphite, the binder is any one of sodium carboxymethyl cellulose, polyvinylidene fluoride and polytetrafluoroethylene, and the current collector is any one of titanium foil, foam nickel, foam copper and aluminum foil.

Description

Covalent modification method of high-performance lignin-based electrode material Technical Field The invention belongs to the technical field of biomass-based supercapacitors, and particularly relates to a method for improving energy storage property of a lignin-based supercapacitor electrode material by using a covalent modification means. Background Along with the increasing severity of environmental problems, new energy sources such as wind energy, photovoltaic energy and tidal energy play an increasingly important role in a power supply system, but the energy sources are affected by multiple natural factors, and output has the defects of intermittence, instability and the like. The super capacitor as a novel energy storage device can be widely applied to the storage of new energy sources due to the advantages of rapid charge and discharge capability, high power density, long cycle life and the like, wherein an electrode material is a key for influencing the energy storage performance. The traditional supercapacitor electrode material is mainly prepared by utilizing non-renewable fossil energy sources such as coal, asphalt and the like, and has the defects of high cost, non-environmental friendliness and the like. It is highly desirable to find a low cost, environmentally friendly renewable feedstock as a precursor for preparing electrodes. Lignin has the characteristics of being renewable, high in carbon content, rich in reserves and the like, so that the lignin becomes an ideal precursor for preparing electrode materials. However, the short side chain of lignin is easy to break in carbonization process to form gas escape, and a large number of generated defect structures can prevent the transmission of electrons on the surface of the material, so that the electrochemical performance of the material is reduced. Therefore, enhancing the thermal stability of the lignin short side chain and improving the graphitization degree become key for preparing the high-performance supercapacitor electrode material. Currently, researchers use dialysis to fractionate lignin to obtain lignin fractions with a molecular weight close to that of lignin and a high weight average molecular weight, so as to reduce the generation of defective structures in the carbonization process of lignin. However, such methods are time consuming and labor intensive and have low yields. Therefore, development of a simple and high-yield modification means improves the thermodynamic property of lignin so as to reduce the formation of structural defects in the carbonization process, has important significance for development and utilization of low-cost and high-performance lignin-based supercapacitors, and is also a key scientific problem to be solved in the fields of biomass and supercapacitors. Disclosure of Invention The invention aims to provide a preparation method of a covalent-regulation lignin-based carbon material, which improves the stability of lignin in a covalent bonding mode. The technical scheme adopted by the invention is that the preparation method of the covalent adjustment lignin-based carbon material is implemented according to the following steps: Step 1, adding kraft lignin and DMF into a conical flask, fully stirring until the kraft lignin and DMF are completely dissolved, adding different amounts of difunctional reagents for reaction, finally pouring the reaction solution into a beaker filled with deionized water (dropwise adding HCl) for reverse precipitation, filtering, and freeze-drying to obtain modified lignin; And 2, placing the modified lignin in a tubular furnace, carbonizing in an inert atmosphere, mixing and grinding the carbonized material and the alkali metal compound to obtain a mixture. Placing the mixture into a tubular furnace for activation, washing the mixture by deionized water until the pH value is neutral, and drying the mixture to obtain a lignin-based carbon material; and 3, grinding the lignin-based carbon material, the conductive agent and the binder into slurry in an agate mortar, uniformly coating the slurry on a current collector, and drying to obtain the lignin-based electrode material. The present invention is also characterized in that, In the step 1, the mass of the kraft lignin is 1-6 g, the mass of the DMF is 5-12 g, the difunctional reagent is any one of adipic acid, isophorone diisocyanate and terephthalic acid, the mass fraction of the difunctional reagent is 0.1-50 wt%, the reaction temperature is 20-80 ℃ and the reaction time is 24-96 h. In the step 2, the alkali metal compound is any one of calcium hydroxide, sodium hydroxide and potassium hydroxide, and the mass ratio of the modified lignin to the alkali metal compound is 1:1-4. The inert atmosphere mainly comprises nitrogen, helium and argon, the gas flow rate is 1-20 mL/min, the heating rate is 1-10 ℃/min, the carbonization temperature is 800-1200 ℃, the activation temperature is 600-1000 ℃, and the heat preservation time is 30