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CN117059759A - Heteroatom doped hard carbon-soft carbon composite material and preparation method and application thereof - Google Patents

Heteroatom doped hard carbon-soft carbon composite material and preparation method and application thereof Download PDF

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Publication number
CN117059759A
CN117059759A CN202310647044.2A CN202310647044A CN117059759A CN 117059759 A CN117059759 A CN 117059759A CN 202310647044 A CN202310647044 A CN 202310647044A CN 117059759 A CN117059759 A CN 117059759A
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hard carbon
precursor
composite material
soft
heteroatom
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梁金
梁慧宇
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Shenzhen Jinpai New Energy Technology Co ltd
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Shenzhen Jinpai New Energy Technology Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Carbon And Carbon Compounds (AREA)

Abstract

The invention relates to the technical field of secondary batteries, in particular to a heteroatom doped hard carbon-soft carbon composite material and a preparation method and application thereof, wherein the preparation method comprises the following steps: s1, oxidizing a hard carbon precursor, an oxidant and an organic acid in an aqueous solution of ammonium persulfate to obtain an oxidized hard carbon precursor; s2, uniformly dispersing the oxidized hard carbon precursor, the aminated asphalt precursor, the amino acid and the silane coupling agent in water, and obtaining a hard carbon-soft carbon precursor material through hydrothermal reaction; s3, transferring the hard carbon-soft carbon precursor material into a tube furnace, and introducing heteroatom gas for carbonization to obtain the heteroatom doped hard carbon-soft carbon composite material. According to the invention, the hard carbon precursor and the soft carbon precursor are subjected to crosslinking carbonization through the amphoteric compound (amino acid) and the coupling agent, and the heteroatom doping is performed to obtain the heteroatom doped hard carbon-soft carbon composite material, so that the energy density and the power performance of the hard carbon are improved.

Description

Heteroatom doped hard carbon-soft carbon composite material and preparation method and application thereof
Technical Field
The invention relates to the technical field of secondary batteries, in particular to a heteroatom doped hard carbon-soft carbon composite material, and a preparation method and application thereof.
Background
The hard carbon belongs to non-graphitized carbon, the structural characteristics can be summarized as short-range ordered and long-range disordered, meanwhile, the hard carbon is pyrolytic carbon of a high molecular polymer, and is difficult to graphitize, and the hard carbon has a mutually staggered lamellar structure, so that lithium ions can be inserted and extracted from various angles, the charge and discharge speed is greatly improved, and the hard carbon has excellent multiplying power, circulation performance and low-temperature performance. But it has a low reversible capacity (300 mAh/g), low first efficiency (80%), low compacted density (1.0 g/cm) 3 ) Defects such as poor electronic conductivity limit the application of the material. While soft carbon is an amorphous carbon which is easily graphitized and has a moderate compacted density (1.3 g/cm) 3 ) The specific capacity is moderate (350 mAh/g), but the voltage platform is high, the electronic conductivity is moderate, the first efficiency is high (85%), and the like. Compared with artificial graphite, the soft carbon and the hard carbon have the problems of low specific capacity, deviation of electronic conductivity and the like, the exertion of the power performance of the soft carbon material is influenced, and one of the power of the hard carbon material/the soft carbon material is that the metal or nonmetal atoms doped with the conductivity change the distribution state of the holes and free electrons of the material, so that the electronic conductivity of the material is improved.
Disclosure of Invention
The first aspect of the invention provides a method for preparing a heteroatom doped hard carbon-soft carbon composite material, comprising the following steps:
s1, oxidizing a hard carbon precursor, an oxidant and an organic acid in an aqueous solution of ammonium persulfate to obtain an oxidized hard carbon precursor;
s2, uniformly dispersing the oxidized hard carbon precursor, the aminated asphalt precursor, the amino acid and the silane coupling agent in water, and obtaining a hard carbon-soft carbon precursor material through hydrothermal reaction;
s3, transferring the hard carbon-soft carbon precursor material into a tube furnace, and introducing heteroatom gas for carbonization to obtain the heteroatom doped hard carbon-soft carbon composite material.
In some embodiments, the mass ratio of the hard carbon precursor, the oxidizing agent, the organic acid, and the ammonium persulfate is 100: (10-30): (1-5): (1-5).
The applicant finds that compared with the prior art, the oxidized hard carbon precursor prepared by the method has the advantages that holes are formed by polycondensation of carboxyl/hydroxyl of the oxidized hard carbon precursor in the carbonization process, the lithium/sodium storage function of the material is improved, and the mass ratio of the oxidant, the organic acid and the ammonium persulfate is controlled to be (10-30): (1-5): (1-5) can avoid forming more macropores to reduce the compaction density of the material, and has the primary efficiency of the material.
Further, the step S1 comprises the steps of fully stirring and mixing a hard carbon precursor, an oxidant and an organic acid in an aqueous solution of ammonium persulfate, filtering, drying, and oxidizing at 300-500 ℃ for 1-6h under the condition of inert atmosphere to obtain an oxidized hard carbon precursor.
In some embodiments, the hard carbon precursor comprises at least one of phenolic resin, epoxy resin, furfural resin, coconut shell, apricot shell, lignin, sweet potato starch, wheat starch, corn starch.
In some embodiments, the oxidizing agent comprises at least one of potassium permanganate, potassium dichromate, concentrated sulfuric acid, concentrated nitric acid, hydrogen peroxide.
In some embodiments, the amino acid comprises at least one of lysine, tryptophan, methionine, phenylalanine, leucine.
In some embodiments, the organic acid comprises at least one of oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, caprylic acid, adipic acid, malonic acid, succinic acid, maleic acid, tartaric acid, benzoic acid, phenylacetic acid, phthalic acid, terephthalic acid, valeric acid, caproic acid, capric acid, stearic acid, palmitic acid, acrylic acid, 9, 10-dihydroxystearic acid, 3, 4-dihydroxyphenylacetic acid.
Further, the step S2 comprises the steps of uniformly dispersing an oxidized hard carbon precursor, an aminated asphalt precursor, amino acid and a silane coupling agent in water, reacting for 1-6 hours at the temperature of 100-200 ℃ through a hydrothermal reaction, filtering, and freeze-drying for 24 hours at the temperature of minus 40 ℃ to obtain the hard carbon-soft carbon precursor material.
In some embodiments, the mass ratio of the oxidized hard carbon precursor, the aminated pitch precursor, the amino acid, the silane coupling agent is 100: (10-50): (5-20): (1-5).
In some embodiments, the method of preparing an aminated pitch precursor comprises: adding the oxidized asphalt into an organic solvent of a diamino coupling agent for dispersion reaction to obtain an aminated asphalt precursor. Preferably, the oxidized asphalt is added into an organic solvent of the diamino coupling agent to be uniformly dispersed, and reacts for 1-6 hours at the temperature of 50-100 ℃, and then the amino asphalt is obtained through filtration and vacuum drying, wherein the mass ratio of the oxidized asphalt to the diamino coupling agent is preferably 100: (1-30).
In some embodiments, the organic solvent may be selected from the classes commonly used in the art, including but not limited to N-methylpyrrolidone.
In some embodiments, the bis-amino coupling agent comprises at least one of N- (2-aminoethyl) -3-aminopropyl methyldimethoxy silane, N- β - (aminoethyl) - γ -aminopropyl methyldimethoxy silane, N- (β -aminoethyl) - γ -aminopropyl triethoxy silane.
Compared with the oxidized asphalt in the prior art, the amino on the surface of the aminated asphalt can better react with the hydroxyl/carboxyl on the surface of the oxidized hard carbon precursor to generate the amide group of the chemical bond connection, so that the structural stability between materials is further improved. In the research, the mass ratio of the controlled oxidized asphalt to the diamino coupling agent is 100: (1-30) can improve the specific capacity of the material, the addition of the diamino coupling agent is too much to reduce the specific capacity, and the addition is too little to crosslink to a low degree, so that the improvement of the specific capacity is limited.
In some embodiments, the silane coupling agent may be selected from the classes commonly used in the art including, but not limited to, methyltriethoxysilane, methyltrimethoxysilane, propyltriethoxysilane, propyltrimethoxysilane.
Further, S3 comprises transferring hard carbon-soft carbon precursor material into a tube furnace, introducing heteroatom gas for carbonization, carbonizing at 800-1500 ℃ for 1-6h, cooling to room temperature under inert gas atmosphere, and pulverizing to obtain heteroatom doped hard carbon-soft carbon composite material.
In some embodiments, the heteroatom gas comprises at least one of borane, phosphine, ammonia, hydrogen sulfide.
Further, the flow rate of the heteroatom gas is 100-500mL/min.
The flow of the heteroatom gas is controlled, so that the electronic conductivity of the material and the density of the material can be improved, the morphology feature of the composite material can be influenced by overlarge flow or overlarge flow, the surface density of the material can be poor due to overlarge flow, and the electronic conductivity of the improved material can be limited due to overlarge flow.
The second aspect of the invention provides a heteroatom doped hard carbon-soft carbon composite material obtained by the preparation method.
The third aspect of the invention provides an application of the heteroatom doped hard carbon-soft carbon composite material in the field of preparing secondary batteries.
Compared with the prior art, the invention has the following beneficial effects:
(1) The hydroxyl/carboxyl on the surface of the oxidized hard carbon precursor and the amino on the surface of the aminated asphalt are utilized to generate amide groups for chemical bond connection, so that the structural stability between materials is improved; and meanwhile, the specific capacity and the energy density of the composite material are improved by utilizing the coupling effect of the silane coupling agent and the silicon-based material obtained after carbonization.
(2) Heteroatom gas is cracked through a vapor deposition method and deposited in pores, so that the heteroatom changes the distribution state of free electrons, the electron conductivity of the material is improved, and the power performance is improved.
(3) According to the invention, the hard carbon precursor and the soft carbon precursor are subjected to crosslinking carbonization through the amphoteric compound (amino acid) and the coupling agent, and the heteroatom doping is performed to obtain the heteroatom doped hard carbon-soft carbon composite material, so that the energy density and the power performance of the hard carbon are improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings which are required in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are some embodiments of the invention and that other drawings may be obtained from these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an SEM image of a heteroatom doped hard carbon-soft carbon composite material prepared according to example 1.
Detailed Description
The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
A first aspect of the present embodiment provides a method for preparing a heteroatom doped hard carbon-soft carbon composite material, the method comprising the steps of:
s1, fully stirring and mixing 100g of hard carbon precursor phenolic resin, 20g of oxidant potassium permanganate and 3g of organic acid oxalic acid in 60g of ammonium persulfate aqueous solution (5 wt%) and filtering, vacuum drying at 80 ℃ for 24 hours, and oxidizing at 400 ℃ for 3 hours under the argon condition to obtain an oxidized hard carbon precursor;
s2, uniformly dispersing 100g of oxidized hard carbon precursor, 30g of amination asphalt precursor, 10g of lysine and 3g of silane coupling agent methyltriethoxysilane in 1000g of water, reacting for 3 hours at 150 ℃ through hydrothermal reaction, filtering, and freeze-drying for 24 hours at-40 ℃ to obtain a hard carbon-soft carbon precursor material;
the preparation method of the amination asphalt precursor comprises the following steps: adding 20g of a diamino coupling agent N- (2-aminoethyl) -3-aminopropyl methyl dimethoxy silane into 500g of an organic solvent N-methyl pyrrolidone, uniformly dispersing, adding 100g of oxidized asphalt, uniformly mixing, reacting for 3 hours at 80 ℃, filtering, and vacuum drying for 24 hours at 80 ℃ to obtain aminated asphalt;
s3, transferring the hard carbon-soft carbon precursor material into a tube furnace, introducing borane gas for carbonization (300 mL/min), carbonizing for 3 hours at 1200 ℃, cooling to room temperature (25 ℃) under the inert gas atmosphere of argon, and crushing to obtain the heteroatom doped hard carbon-soft carbon composite material.
The second aspect of the embodiment provides a heteroatom doped hard carbon-soft carbon composite material obtained by the preparation method.
A third aspect of the present embodiment provides an application of the heteroatom doped hard carbon-soft carbon composite material in the field of preparing secondary batteries.
Example 2
A first aspect of the present embodiment provides a method for preparing a heteroatom doped hard carbon-soft carbon composite material, the method comprising the steps of:
s1, fully stirring and mixing 100g of hard carbon precursor coconut shell, 20g of oxidant potassium dichromate and 1g of organic acid oxalic acid in 100g of ammonium persulfate aqueous solution (1 wt%) and filtering, vacuum drying at 80 ℃ for 24 hours, and oxidizing at 300 ℃ for 6 hours under the argon condition to obtain an oxidized hard carbon precursor;
s2, uniformly dispersing 100g of oxidized hard carbon precursor, 10g of aminated asphalt precursor, 5g of tryptophan and 1g of silane coupling agent methyltrimethoxysilane in 1000g of water, reacting for 6 hours at 100 ℃ through hydrothermal reaction, filtering, and freeze-drying for 24 hours at-40 ℃ to obtain a hard carbon-soft carbon precursor material;
the preparation method of the amination asphalt precursor comprises the following steps: adding 1g of a diamino coupling agent N-beta- (aminoethyl) -gamma-aminopropyl methyl dimethoxy silane into 500g of an organic solvent N-methyl pyrrolidone, uniformly dispersing, adding 100g of oxidized asphalt, uniformly mixing, reacting for 6 hours at 50 ℃, filtering, and vacuum drying for 24 hours at 80 ℃ to obtain aminated asphalt;
s3, transferring the hard carbon-soft carbon precursor material into a tube furnace, introducing phosphine gas for carbonization (100 mL/min), carbonizing for 6 hours at 800 ℃, cooling to room temperature (25 ℃) in an argon inert gas atmosphere, and crushing to obtain the heteroatom doped hard carbon-soft carbon composite material.
The second aspect of the embodiment provides a heteroatom doped hard carbon-soft carbon composite material obtained by the preparation method.
A third aspect of the present embodiment provides an application of the heteroatom doped hard carbon-soft carbon composite material in the field of preparing secondary batteries.
Example 3
A first aspect of the present embodiment provides a method for preparing a heteroatom doped hard carbon-soft carbon composite material, the method comprising the steps of:
s1, fully stirring and mixing 100g of hard carbon precursor lignin, 30g of oxidant hydrogen peroxide and 5g of organic acid oxalic acid in 500g of ammonium persulfate aqueous solution (10 wt%) and filtering, vacuum drying at 80 ℃ for 24 hours, and oxidizing at 500 ℃ for 1 hour under the condition of argon to obtain an oxidized hard carbon precursor;
s2, uniformly dispersing 100g of oxidized hard carbon precursor, 10g of aminated asphalt precursor, 20g of methionine and 5g of silane coupling agent propyltriethoxysilane in 1000g of water, reacting for 1h at 200 ℃ through hydrothermal reaction, filtering, and freeze-drying at-40 ℃ for 24h to obtain a hard carbon-soft carbon precursor material;
the preparation method of the amination asphalt precursor comprises the following steps: adding 30g of a diamino coupling agent N- (beta-aminoethyl) -gamma-aminopropyl triethoxysilane into 500g of an organic solvent N-methylpyrrolidone, uniformly dispersing, adding 100g of oxidized asphalt, uniformly mixing, reacting for 1h at 100 ℃, filtering, and vacuum drying at 80 ℃ for 24h to obtain aminated asphalt;
s3, transferring the hard carbon-soft carbon precursor material into a tube furnace, introducing hydrogen sulfide gas for carbonization (500 mL/min), carbonizing for 1h at 1500 ℃, cooling to room temperature (25 ℃) in an argon inert gas atmosphere, and crushing to obtain the heteroatom doped hard carbon-soft carbon composite material.
The second aspect of the embodiment provides a heteroatom doped hard carbon-soft carbon composite material obtained by the preparation method.
A third aspect of the present embodiment provides an application of the heteroatom doped hard carbon-soft carbon composite material in the field of preparing secondary batteries.
Comparative example 1
The present comparative example provides a method for preparing a heteroatom doped hard carbon-soft carbon composite material, and the specific embodiment is the same as example 1, in that the method comprises the following steps:
s1, uniformly dispersing 100g of phenolic resin, 30g of asphalt, 10g of lysine and 3g of silane coupling agent methyltriethoxysilane in 1000g of water, reacting for 3 hours at 150 ℃ through hydrothermal reaction, filtering, and freeze-drying for 24 hours at-40 ℃ to obtain a hard carbon-soft carbon precursor material;
s2, transferring the hard carbon-soft carbon precursor material into a tube furnace, introducing borane gas for carbonization (300 mL/min), carbonizing for 3 hours at 1200 ℃, cooling to room temperature (25 ℃) in an argon inert gas atmosphere, and crushing and grading to obtain the heteroatom doped hard carbon-soft carbon composite material.
Comparative example 2
The present comparative example provides a method for preparing a heteroatom doped hard carbon-soft carbon composite material, and the specific embodiment is the same as example 1, in that S3 comprises: transferring the hard carbon-soft carbon precursor material into a tube furnace, carbonizing for 3h at 1200 ℃, cooling to room temperature (25 ℃) under the inert gas atmosphere of argon, crushing and grading to obtain the heteroatom doped hard carbon-soft carbon composite material.
Comparative example 3
The comparative example provides a method for preparing a heteroatom doped hard carbon-soft carbon composite material, and the specific implementation mode is the same as example 1, except that oxidized asphalt is used for replacing an amination asphalt precursor.
Performance testing
The heteroatom doped hard carbon-soft carbon composites prepared in examples and comparative examples were subjected to the following test.
1. SEM test
SEM test of the heteroatom doped hard carbon-soft carbon composite material prepared in example 1 shows that the composite material prepared in example 1 has a spheroid structure, uniform size distribution and particle size of 10-15 μm as shown in FIG. 1.
2. Physical and chemical properties and button cell testing
The heteroatom doped hard carbon-soft carbon composites prepared in examples 1-3 and comparative examples 1-2 were tested for particle size, tap density, specific surface area, elemental analysis (heteroatom content, boron, nitrogen, phosphorus, sulfur) and specific capacity. The testing method comprises the following steps: GBT-24533-2019 lithium ion battery graphite anode material.
The heteroatom doped hard carbon-soft carbon composites obtained in examples 1-3 and comparative examples 1-2 were assembled into button cells A1, A2, A3, B1, B2, respectively; the preparation method comprises the following steps: adding binder, conductive agent and solvent into the cathode material, stirring to slurry, coating on copper foil (single-side thickness 120 μm), oven drying, and rolling. The binder used is LA132 binder, conductive agent SP, negative electrode material is hard carbon-soft carbon composite material prepared in examples 1-3 and comparative examples 1-2, solvent is secondary distilled water, and the proportion is: negative electrode material: SP: LA132: secondary distilled water = 95g:1g:4g:220mL, preparing a negative electrode plate; the electrolyte is LiPF 6 And (2) EC+DEC (volume ratio is 1:1, concentration is 1.3 mol/L), the metal lithium sheet is a counter electrode, the diaphragm adopts a composite film (PE/PP/PE) of polyethylene PE and polypropylene PP, the simulated battery is assembled in a glove box filled with argon, electrochemical performance is carried out on a Wuhan blue electric CT2001A type battery tester, charging and discharging voltage ranges from 0.00V to 2.0V, and charging and discharging rate is 0.1C. The button cell was also tested for its rate (2C/0.1C) and cycle performance (0.2C/0.2C, 200 times) and the test results are shown in Table 1 below:
TABLE 1
As can be seen from table 1, compared with comparative examples 1-2, the first discharge capacity, first efficiency, rate capability and cycle performance of the heteroatom-doped hard carbon-soft carbon composite material prepared in examples 1-3 are significantly improved, because in the present invention, the doping of the heteroatom in the composite material improves the electronic conductivity of the material, thereby improving the specific capacity and first efficiency, rate capability of the material; meanwhile, hydroxyl/carboxyl on the surface of the oxidized hard carbon precursor and amino on the surface of the aminated asphalt are utilized to generate amide groups with chemical bond connection, so that the structural stability among materials is improved, and the cycle performance is improved.
3. Soft package battery test:
the hetero atom-doped hard carbon-soft carbon composite materials in examples 1-3 and comparative examples 1-2 were used as negative electrodes, and the negative electrode sheets were prepared by slurry mixing and coating, using a ternary material (LiNi 1/3 Co 1/3 Mn 1/3 O 2 ) As positive electrode, with LiPF 6 (the solvent is EC+DEC, the volume ratio is 1:1, the electrolyte concentration is 1.1 mol/L) is taken as electrolyte, and a Celgard2400 membrane is taken as a diaphragm, so that the 5Ah soft-package battery is prepared.
3.1 rate Performance test
The charging and discharging voltage ranges from 2.8V to 4.2V, the testing temperature is 25+/-3.0 ℃, the charging is carried out at 1.0C, 2.0C, 3.0C and 5.0C, the discharging is carried out at 1.0C, the constant current ratio and the temperature of the battery under different charging modes are tested, and the results are shown in Table 2:
TABLE 2
As can be seen from Table 2, the rate charging performance of the soft-pack batteries prepared in examples 1-3 is significantly better than that of comparative examples 1-2, i.e. the charging time is shorter, indicating that the composite anode material of the invention has good quick-charge performance. The reason may be that the doping of the embodiment material with heteroatoms improves the electronic conductivity of the material, and amide groups connected by chemical bonds improve the structural stability between the materials, reduce the impedance by contact, improve tap density, and improve the rate capability; meanwhile, heteroatom gas is cracked through a vapor deposition method and deposited in pores, so that the distribution state of free electrons is changed, the electronic conductivity of the material is improved, and the power performance is improved.
3.2 cycle Performance test
The following experiments were performed on the pouch cells prepared using the heteroatom doped hard carbon-soft carbon composite materials of examples 1 to 3 and comparative examples 1 to 2: the capacity retention rate was measured by performing charge and discharge cycles 100 times, 300 times, and 500 times in this order with a charge and discharge rate of 2C/2C and a voltage range of 2.8-4.2V, and the results are shown in Table 3:
TABLE 3 Table 3
As can be seen from table 3, the cycle performance of the lithium ion battery prepared from the heteroatom doped hard carbon-soft carbon composite material prepared by the invention is obviously superior to that of the comparative example in each stage, and the reason is probably that the structural stability between materials is improved and the cycle performance is improved by utilizing the chemical reaction of hydroxyl/carboxyl on the surface of the oxidized hard carbon precursor and amino on the surface of the aminated asphalt to generate amide groups for chemical bond connection.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.

Claims (10)

1. A method for preparing a heteroatom doped hard carbon-soft carbon composite material, which is characterized by comprising the following steps:
s1, oxidizing a hard carbon precursor, an oxidant and an organic acid in an aqueous solution of ammonium persulfate to obtain an oxidized hard carbon precursor;
s2, uniformly dispersing the oxidized hard carbon precursor, the aminated asphalt precursor, the amino acid and the silane coupling agent in water, and obtaining a hard carbon-soft carbon precursor material through hydrothermal reaction;
s3, transferring the hard carbon-soft carbon precursor material into a tube furnace, and introducing heteroatom gas for carbonization to obtain the heteroatom doped hard carbon-soft carbon composite material.
2. The method for preparing the heteroatom doped hard carbon-soft carbon composite material according to claim 1, wherein the mass ratio of the hard carbon precursor to the oxidant to the organic acid to the ammonium persulfate is 100: (10-30):
(1-5)：(1-5)。
3. the method for preparing the heteroatom doped hard carbon-soft carbon composite material according to claim 1, wherein the mass ratio of the oxidized hard carbon precursor to the aminated pitch precursor to the amino acid to the silane coupling agent is 100: (10-50): (5-20): (1-5).
4. The method for preparing a heteroatom doped hard carbon-soft carbon composite material according to claim 1, wherein the oxidant comprises at least one of potassium permanganate, potassium dichromate, concentrated sulfuric acid, concentrated nitric acid, and hydrogen peroxide.
5. The method for preparing the heteroatom doped hard carbon-soft carbon composite material according to claim 1, wherein the method for preparing the aminated pitch precursor comprises the following steps: adding the oxidized asphalt into an organic solvent of a diamino coupling agent for dispersion reaction to obtain an aminated asphalt precursor.
6. The method of preparing a heteroatom doped hard carbon-soft carbon composite according to claim 5, wherein the diamino coupling agent comprises at least one of N- (2-aminoethyl) -3-aminopropyl methyldimethoxy silane, N- β - (aminoethyl) - γ -aminopropyl methyldimethoxy silane, N- (β -aminoethyl) - γ -aminopropyl triethoxy silane.
7. The method of preparing a heteroatom doped hard carbon-soft carbon composite according to claim 1, wherein the heteroatom gas comprises at least one of borane, phosphine, ammonia, and hydrogen sulfide.
8. The method of claim 1, wherein the hard carbon precursor comprises at least one of phenolic resin, epoxy resin, furfural resin, coconut shell, apricot shell, lignin, sweet potato starch, wheat starch, and corn starch.
9. A heteroatom doped hard carbon-soft carbon composite material obtained according to the method of any one of claims 1-8.
10. Use of the heteroatom doped hard carbon-soft carbon composite material according to any one of claims 1-8 in the field of preparing secondary batteries.
CN202310647044.2A 2023-06-01 2023-06-01 Heteroatom doped hard carbon-soft carbon composite material and preparation method and application thereof Pending CN117059759A (en)

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Publication number Priority date Publication date Assignee Title
CN118851176A (en) * 2024-09-23 2024-10-29 上海兆钠新能源科技有限公司 Preparation method of modified hard carbon negative electrode material, negative electrode sheet containing the same, and sodium ion battery

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118851176A (en) * 2024-09-23 2024-10-29 上海兆钠新能源科技有限公司 Preparation method of modified hard carbon negative electrode material, negative electrode sheet containing the same, and sodium ion battery

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