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CN-122010091-A - Preparation method of hard carbon anode material based on cellulose

CN122010091ACN 122010091 ACN122010091 ACN 122010091ACN-122010091-A

Abstract

The invention provides a preparation method of a hard carbon anode material based on cellulose, which relates to the field of battery electrode material preparation, and comprises the steps of preparing a composite solvent system, swelling cellulose, separating a regenerated cellulose phase, filtering, washing, drying, pyrolyzing and carbonizing, wherein the swelling cellulose comprises the steps of sequentially adding cellulose, KH560 and triethylamine into a DMAc/LiCl composite solvent, stirring and mixing to form a premix system, then placing the premix system into a constant-temperature oil bath pot for stirring and swelling, and performing vacuum defoaming after swelling, the regenerated cellulose phase separation comprises the steps of preparing a coagulating bath in advance, uniformly dripping the cellulose composite dispersion liquid after vacuum defoaming into the coagulating bath, and standing at constant temperature after the dripping is completed to obtain a regenerated phase dispersion liquid. The method prepares the hard carbon anode material with excellent electrochemical performance through a synergistic process of swelling cellulose molecular chain-phase separation and reconstruction of a crystal structure.

Inventors

  • ZHAO LEI
  • SUN YITONG
  • XI KANG

Assignees

  • 陇东学院

Dates

Publication Date
20260512
Application Date
20260414

Claims (10)

  1. 1. A preparation method of a hard carbon anode material based on cellulose is characterized by comprising the following steps: Step S1, preparing a composite solvent system, namely adding anhydrous LiCl into a DMAc solvent after pretreatment, stirring in a constant-temperature oil bath pot to obtain the DMAc/LiCl composite solvent, and sealing for later use; Step S2, swelling cellulose, namely sequentially adding cellulose, KH560 and triethylamine into a DMAc/LiCl composite solvent, stirring and mixing to form a premix system, and then placing the premix system into a constant-temperature oil bath kettle for stirring and swelling, and performing vacuum defoaming after swelling to obtain a cellulose composite dispersion liquid, wherein the mass ratio of the cellulose, KH560, triethylamine and DMAc/LiCl composite solvent is 35-45:0.42-0.54:0.7-0.9:1000; s3, cellulose regenerated phase separation, namely pre-preparing a coagulating bath, dropwise adding cellulose composite dispersion liquid subjected to vacuum defoaming into the coagulating bath at a constant speed, and standing at a constant temperature after dropwise adding to obtain regenerated phase dispersion liquid, wherein the coagulating bath preparation comprises the steps of adding deionized water and polyethylene glycol diglycidyl ether into a coagulating bath tank, and stirring at a low speed at a rotating speed of 45-55 rpm until the deionized water and the polyethylene glycol diglycidyl ether are completely dissolved; S4, filtering and washing, namely sequentially carrying out solid-liquid separation, primary coordination washing, secondary anchoring washing and tertiary solvent replacement on the regenerated phase dispersion liquid to obtain a cellulose regenerated wet material; s5, drying, namely performing supercritical CO 2 gradient drying on the cellulose regenerated wet material filtered and washed in the step S4 to obtain cellulose regenerated powder; And S6, performing pyrolytic carbonization, namely sequentially performing pyrolytic carbonization and etching treatment on the cellulose regenerated powder to obtain the hard carbon anode material of the sodium ion battery.
  2. 2. The preparation method of the cellulose-based hard carbon anode material is characterized in that in the step S1, the anhydrous LiCl is subjected to pretreatment, namely, the anhydrous LiCl is placed in a vacuum oven, dried for 3.5-4.5 hours at the temperature of 118-122 ℃ and the vacuum degree of-0.08 to-0.1 MPa, and immediately placed in a dryer to be cooled to the room temperature after being dried.
  3. 3. The preparation method of the cellulose-based hard carbon anode material is characterized in that in the step S1, the mass ratio of the anhydrous LiCl to the DMAc solvent is 5-15:100, and stirring is carried out in a constant-temperature oil bath pot at 30-60 ℃ at a rotating speed of 280-320 rpm for 0.5-2 h.
  4. 4. The method for preparing the hard carbon anode material based on the cellulose, as claimed in claim 3, wherein in the step S2, the premixing system is stirred for 8-12 min at a rotating speed of 180-220 rpm.
  5. 5. The preparation method of the hard carbon anode material based on the cellulose, which is disclosed in claim 4, is characterized in that the mesh number of the cellulose is 200-1000 meshes, and the cellulose is one or more of coconut fiber, bamboo fiber and straw fiber.
  6. 6. The preparation method of the cellulose-based hard carbon anode material is characterized in that in the step S2, swelling is carried out in a constant-temperature oil bath pot with the temperature of 70-75 ℃ and the rotating speed of 180-220 rpm, stirring is carried out continuously, low-frequency pulse ultrasound is synchronously applied in the stirring process, and the ultrasonic parameters are 28-32 kHz in frequency, 7.5-8.5W/cm 2 in power density and 1:3 in pulse duty ratio, and the continuous treatment is carried out for 12-24 hours.
  7. 7. The preparation method of the hard carbon anode material based on the cellulose, which is disclosed in claim 6, is characterized in that in the step S3, the volume mass ratio of deionized water to polyethylene glycol diglycidyl ether is 9-11 L:27-33 g, and the solution is placed in a constant-temperature water bath after the dissolution, so that the system temperature is stabilized at 20-50 ℃.
  8. 8. The preparation method of the hard carbon anode material based on the cellulose is characterized in that in the step S4, a regenerated phase dispersion liquid obtained in the step S3 is subjected to vacuum suction filtration by a Buchner funnel to obtain a cellulose wet filter cake, the cellulose wet filter cake is subjected to suction filtration until no filtrate drops, the first-stage coordination washing is performed, the mass volume ratio of the cellulose wet filter cake to the first-stage coordination washing liquid is 1:20, the cellulose wet filter cake and the first-stage coordination washing liquid are stirred at the temperature of 23-27 ℃ for 28-32 min at the rotating speed of 140-160 rpm, then the vacuum filtration is performed, the operation is repeated for 3-4 times, the second-stage anchoring washing is performed, the filter cake obtained after the first-stage coordination washing is added into the second-stage anchoring washing liquid, the mass volume ratio of the filter cake and the second-stage anchoring washing liquid is 1:10, the filter cake is soaked at the temperature of 23-27 ℃ for 28-32 min, then the vacuum filtration is performed, the third-stage solvent replacement is performed, the filter cake obtained after the rinsing is subjected to vacuum filtration is added into absolute ethanol, the filter cake obtained after the vacuum filtration is subjected to the mass ratio of the filter cake and the absolute ethanol is stirred at the rotating speed of 1:15-160 rpm, the rotating speed of the second-160 rpm is repeated at the rotating speed of 23-160 ℃ for 3-160 ℃ and the rotating speed of the fiber is obtained after the second-160 ℃ is repeated.
  9. 9. A preparation method of a hard carbon anode material based on cellulose is characterized in that in step S5, supercritical CO 2 gradient drying is adopted, cellulose regenerated wet materials are uniformly paved in a material basket of a supercritical reaction kettle, the material basket is filled with the cellulose regenerated wet materials with the thickness not exceeding 2cm, the reaction kettle is sealed after the material basket is filled, liquid CO 2 is introduced into the reaction kettle, the temperature is slowly increased to 37-39 ℃, the pressure is synchronously increased to 8.5-9.5 MPa, static soaking is carried out under constant temperature and constant pressure for 2.8-3.2 hours, then the pressure in the reaction kettle is slowly reduced to normal pressure at a constant speed of 0.14-0.16 MPa/min until the pressure in the reaction kettle is reduced to be constant, the whole process of pressure reduction is stabilized at 37-39 ℃, after the pressure reduction is completed, the reaction kettle is opened, cellulose regenerated powder is taken out, and the cellulose regenerated powder is immediately placed in a dryer for sealing storage.
  10. 10. The preparation method of the hard carbon anode material based on the cellulose is characterized in that in the step S6, the cellulose regenerated powder is uniformly paved in a corundum ark, the filling thickness is not more than 5mm, the ark is placed in a constant temperature area of a tubular furnace, inert gas is introduced as shielding gas, the inert gas is continuously introduced for 28-32 min at the speed of 90-110 mL/min, the temperature is quickly raised to 790-810 ℃ at the temperature rising speed of 19.5-20.5 ℃/min, the temperature is kept for 28-32 min, the temperature is slowly raised to 1300-1500 ℃ at the temperature rising speed of 1.5-2.5 ℃/min, the temperature is kept for 5-7 h, the inert gas is finally cooled to the room temperature at the temperature lowering speed of 4.5-5.5 ℃/min, and the carbonized hard carbon crude product is taken out.

Description

Preparation method of hard carbon anode material based on cellulose Technical Field The invention relates to the technical field of battery electrode material preparation, in particular to a preparation method of a hard carbon negative electrode material based on cellulose. Background Compared with a lithium ion battery, the sodium ion battery has the characteristics of low cost, abundant resources, high output power and the like, and is considered as an important path for relieving resource dependence and reducing battery cost. The sodium ion battery takes sodium ions as charge carriers, unlike graphite materials adopted by a lithium ion battery cathode, hard carbon has a typical disordered carbon structure, no fixed theoretical specific capacity exists, multiple sodium storage mechanisms exist in the sodium ion battery, sodium storage in a platform area is a key for improving the energy density of the sodium-electricity full battery, na + is deintercalated from crystal lattices of a cathode material, and is migrated through electrolyte and is embedded in closed pores from among hard carbon layers to form sodium clusters, electrons synchronously flow from an anode to a cathode through an external circuit to realize charge balance, na + is separated from the closed pores through a graphite sheet layer, returns to the anode through the electrolyte, and flows from the cathode to the anode through the external circuit to externally output electric energy. The hard carbon is a cathode material which only realizes large-scale commercial application of a sodium ion battery at present, the sodium storage capacity of the hard carbon is derived from two major core sites of a graphite domain interlayer embedding site and a closed pore filling site, however, the graphite domain interlayer embedding site depends on densification and ordering of a carbon skeleton (namely, high-temperature carbonization is needed to promote rearrangement of the carbon layer to form graphite microcrystals with larger size and higher order degree, stable reversible embedding capacity is provided), the closed pore filling site depends on a loose porous structure of the carbon skeleton (namely, low-temperature carbonization or pore-forming modification is needed to retain stable nano closed pores, filling capacity of a low-voltage platform and a rapid ion diffusion channel are provided), and the two sites (namely, the graphite domain interlayer embedding site and the closed pore filling site) have fundamental competition in the state of the carbon skeleton structure, and the requirements on the carbon skeleton structure are completely mutually exclusive, so that all core performances of the hard carbon cathode are not in a 'see-saw effect', full breakthrough on core electrochemical performance, mass production cost and scene suitability cannot be realized, namely, large-scale cooperative breakthrough of multi-dimensional performance cannot be realized, and large-scale production and application of the sodium ion battery are restricted. Disclosure of Invention Aiming at the problems existing in the prior art, the invention aims to provide a preparation method of a hard carbon negative electrode material based on cellulose, which is characterized in that the hard carbon negative electrode material with excellent electrochemical performance is efficiently prepared by a synergistic process of swelling cellulose molecular chain-phase separation and reconstruction of a crystal structure, and the conductivity and sodium storage capacity of the hard carbon negative electrode material are optimally regulated and controlled. The aim of the invention is achieved by the following technical scheme: A preparation method of a hard carbon anode material based on cellulose comprises the following steps: Step S1, preparing a composite solvent system, namely pretreating anhydrous LiCl, adding the pretreated anhydrous LiCl into a DMAc (N, N-dimethylacetamide) solvent, stirring the solution in a constant-temperature oil bath pot to obtain a DMAc/LiCl composite solvent, and sealing the solution for later use; Step S2, swelling cellulose, namely sequentially adding cellulose, KH560 and triethylamine into a DMAc/LiCl composite solvent, stirring and mixing to form a premix system, and then placing the premix system into a constant-temperature oil bath kettle for stirring and swelling, and performing vacuum defoaming after swelling to obtain a cellulose composite dispersion liquid; S3, cellulose regenerated phase separation, namely pre-preparing a coagulating bath, uniformly dripping cellulose composite dispersion liquid subjected to vacuum defoaming into the coagulating bath, and standing at a constant temperature after the dripping is finished to obtain regenerated phase dispersion liquid; S4, filtering and washing, namely sequentially carrying out solid-liquid separation, primary coordination washing, secondary anchoring washing and tertiary solvent replacement on