CN115101731A - Negative electrode material, preparation method thereof, negative electrode plate and secondary battery - Google Patents

Negative electrode material, preparation method thereof, negative electrode plate and secondary battery Download PDF

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CN115101731A
CN115101731A CN202210705433.1A CN202210705433A CN115101731A CN 115101731 A CN115101731 A CN 115101731A CN 202210705433 A CN202210705433 A CN 202210705433A CN 115101731 A CN115101731 A CN 115101731A
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negative electrode
silicon
simple substance
preparation
heating
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柯进
马斌
陈杰
杨山
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Huizhou Liwinon 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/364—Composites as mixtures
    • 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
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes

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  • General Chemical & Material Sciences (AREA)
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  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention belongs to the technical field of secondary batteries, and particularly relates to a negative electrode material, a preparation method of the negative electrode material, a negative electrode sheet and a secondary battery. The preparation method of the negative electrode material comprises the following steps: step S1, mixing the silica gel solution with sodium sulfide, heating for reaction, filtering and washing, and removing impurities to obtain elemental silicon; step S2, adding the simple substance silicon, a carbon source, a fluorine source and a structure template material into a solvent, mixing, and freeze-drying to obtain a powder body; and step S3, heating and calcining the powder body in inert gas to obtain the Si @ C-F composite material, namely the cathode material. According to the manufacturing method of the cathode material, simple substance silicon with smaller particle size is obtained through reaction preparation, the simple substance silicon is mixed with carbon and fluorine elements in the structural template material, and the cathode material obtained through calcination effectively solves the problem of volume expansion of silicon and has good rate capability and cycle performance.

Description

Negative electrode material, preparation method thereof, negative electrode plate and secondary battery
Technical Field
The invention belongs to the technical field of secondary batteries, and particularly relates to a negative electrode material, a preparation method of the negative electrode material, a negative electrode sheet and a secondary battery.
Background
The new energy has become one of the hottest topics in the world today, the new energy industry is also developing vigorously, and in the whole energy conversion system, the efficiency of electrochemical conversion is high, the speed is fast, and lithium ion batteries are among the most widely applied energy devices at present. At present, the application scene of the lithium battery is mainly in the fields of 3C consumption, power, energy storage power grids and the like, and with the progress of the times, the whole industry also provides higher requirements for people. Therefore, for the whole battery material, we have to find a new battery material, and the negative electrode material is an important component. At present, the mainstream material of the negative electrode is a graphite material, but the lower theoretical specific capacity (342mAh/g) of the material cannot meet the requirements of people in the future, and the lower lithium intercalation potential of the material also causes a safety problem. Therefore, it is necessary to find a negative electrode material to replace graphite.
Silicon attracts high interest to academic circles and enterprises due to its ultra-high specific capacity (3572mAh/g), abundant resource storage, moderate price. Is considered as one of the candidates for replacing graphite, but the larger volume expansion during the circulation process causes pulverization and deactivation thereof.
Disclosure of Invention
One of the objects of the present invention is: aiming at the defects of the prior art, the preparation method of the cathode material is provided, simple substance silicon with smaller particle size is obtained through reaction preparation, the simple substance silicon is mixed with carbon and fluorine elements in a structural template material, and the cathode material obtained through calcination effectively solves the problem of volume expansion of silicon and has good rate performance and cycle performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
preferably, the weight part ratio of the silica gel solution to the sodium sulfide in the step S1 is 2-10: 0.2-5.
Preferably, the heating reaction temperature in the step S1 is 30-60 ℃, and the reaction time is 0.5-2 h.
Preferably, the weight part ratio of the simple substance silicon to the carbon source to the fluorine source to the structural template material is 1-10: 2-5: 1-6.
Preferably, the particle diameter of the simple substance silicon in the step S1 is 40-80 nm.
Preferably, the step S1 of removing impurities specifically includes immersing the obtained silicon material in a hydrogen fluoride solution, filtering, and drying to obtain elemental silicon.
Preferably, the heating and calcining temperature in the step S3 is 400-600 ℃, and the reaction time is 1-5 h.
The second purpose of the invention is: aiming at the defects of the prior art, the negative electrode material is provided, and has small volume expansion, good rate capability and cycle performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
the negative electrode material is obtained by the preparation method of the negative electrode material.
The third purpose of the invention is: aiming at the defects of the prior art, the negative plate is provided, and has good rate performance and cycle performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
a negative plate comprises the negative electrode material.
The fourth purpose of the invention is that: aiming at the defects of the prior art, the secondary battery is provided, and has good rate capability and cycle performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
a secondary battery comprises the negative plate.
Compared with the prior art, the invention has the beneficial effects that: according to the manufacturing method of the cathode material, simple substance silicon with smaller particle size is obtained through reaction preparation, the simple substance silicon is mixed with carbon and fluorine elements in the structural template material, and the cathode material obtained through calcination effectively solves the problem of volume expansion of silicon and has good rate performance and cycle performance.
Detailed Description
1. A method for manufacturing an anode material, comprising the steps of:
step S1, mixing the silica gel solution with sodium sulfide, heating for reaction, filtering and washing, and removing impurities to obtain simple substance silicon; step S2, adding the simple substance silicon, a carbon source, a fluorine source and a structural template material into a solvent, mixing, and freeze-drying to obtain a powder body;
and step S3, heating and calcining the powder body in inert gas to obtain the Si @ C-F composite material, namely the cathode material.
The invention mixes alkaline silica gel solution and strong reducing substance sodium sulfide to react and generate reducing gas H 2 S, NaOH and nano-sized simple substance silicon prepared by the method have small particle size, and the volume expansion is small when the charging and discharging are carried out, so that the larger volume expansion of the battery cannot be caused. After impurity removal, unreacted silicon dioxide and other impurities can be removed, so that the purity of the simple substance silicon is improved, and the first charge-discharge efficiency is improved. The elemental silicon, the carbon source, the fluorine source and the structural template material are uniformly distributed in the structural template material and fixed by a template method, and then are subjected to freeze drying and high-temperature calcination treatment, so that the problem of agglomeration of the nano silicon powder is solved, meanwhile, a layer of amorphous carbon is coated on the surface of the nano silicon powder, and in the high-temperature treatment, F is doped into a carbon layer and can be in strong electron coupling with Si-F, so that the structural stability and the electronic conductivity of the Si-based material in the circulating process can be enhanced.
According to the manufacturing method of the cathode material, the simple substance silicon with smaller particle size is obtained and is mixed with the carbon and the fluorine element in the structural template material, so that the obtained cathode material effectively solves the problem of volume expansion of silicon, and has good rate performance and cycle performance. Wherein the carbon source is graphite, glucose, citric acid (C) 6 H 8 O 7) The fluorine source is one or more of polyvinylidene fluoride, calcium fluoride and vinylidene fluoride; the structural template material is sodium chloride, and the solvent is deionized water. The inert gas comprises one of nitrogen, argon and helium.
Preferably, the weight part ratio of the silica gel solution to the sodium sulfide in the step S1 is 2-10: 0.2-5. The weight ratio of the silica gel solution to the sodium sulfide is 2-10: 0.2-5, 2-10: 0.5-5, 2-10: 1-4, 4-8: 2-3. Specifically, the weight part ratio of the silica gel solution to the sodium sulfide is 2:0.5, 4:1, 5:2, 7:4 and 10: 5.
Preferably, the heating reaction temperature in the step S1 is 30-60 ℃, and the reaction time is 0.5-2 h. The heating reaction temperature is 30-60 ℃, 40-50 ℃, 30-45 ℃ and 30-40 ℃, specifically, the heating reaction temperature is 30 ℃, 32 ℃, 35 ℃, 37 ℃, 38 ℃, 40 ℃, 43 ℃, 47 ℃, 50 ℃, 54 ℃, 58 ℃ and 60 ℃. The reaction time is 0.5h, 0.8h, 1.2h, 1.5h, 1.8h and 2 h.
Preferably, the weight ratio of the silicon, the carbon source, the fluorine source and the structural template material in the step S2 is 1-10: 2-5: 1-6. The weight ratio of the simple substance silicon to the carbon source to the fluorine source to the structural template material is 3-10: 2-5: 3-5: 2-5, 3-10: 2-5: 3-6, 3-10: 2-5: 1-6, 4-10: 2-5: 1-6, and 5-8: 3-5: 2-5.
Preferably, the particle diameter of the simple substance silicon in the step S1 is 40-80 nm. The particle diameter of the simple substance silicon in the step S1 is 40nm, 45nm, 48nm, 52nm, 56nm, 58nm, 60nm, 65nm, 68nm, 70nm, 75nm and 85 nm.
Preferably, the step S1 of removing impurities specifically includes immersing the obtained silicon material in a hydrogen fluoride solution, filtering, and drying to obtain elemental silicon. The mass concentration of the hydrogen fluoride solution is 5-15 wt%, and the soaking time is 5-20 min. The silicon material is soaked in the hydrogen fluoride solution for transition, so that dry simple substance silicon can be obtained, silicon dioxide and other impurities are removed, and the first efficiency of the battery is improved.
Preferably, the heating and calcining temperature in the step S3 is 400-600 ℃, and the reaction time is 1-5 h. Specifically, the temperature of heating and calcining is 400 ℃, 450 ℃, 500 ℃, 550 ℃ and 600 ℃, and the reaction time is 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h and 5 h.
2. The negative electrode material has less volume expansion, and has good rate performance and cycle performance.
The negative electrode material is obtained by the preparation method of the negative electrode material.
3. A negative plate has good rate performance and cycle performance.
A negative plate comprises the negative electrode material.
4. A secondary battery having good rate capability and cycle performance.
A secondary battery comprises the negative plate.
The secondary battery of the present invention includes a lithium ion battery, a sodium ion battery, a magnesium ion battery, a calcium ion battery, and the like, and preferably, the lithium ion battery is exemplified below. The lithium ion battery comprises a positive plate, an isolating membrane, the negative plate, electrolyte and a shell, wherein the isolating membrane is used for separating the positive plate and the negative plate, and the shell is used for installing and packaging the positive plate, the isolating membrane, the negative plate and the electrolyte.
The active material layer coated on the current collector of the positive plate can be, but is not limited to, an active material of a chemical formula such as Li a Ni x Co y M z O 2-b N b (wherein a is more than or equal to 0.95 and less than or equal to 1.2, x>0, y is more than or equal to 0, z is more than or equal to 0, and x + y + z is 1, 0 is more than or equal to b and less than or equal to 1, M is selected from one or more of Mn and Al, N is selected from one or more of F, P and S), and the positive electrode active material can also be selected from one or more of LiCoO (lithium LiCoO), but not limited to 2 、LiNiO 2 、LiVO 2 、LiCrO 2 、LiMn 2 O 4 、LiCoMnO 4 、Li 2 NiMn 3 O 8 、LiNi 0.5 Mn 1.5 O 4 、LiCoPO 4 、LiMnPO 4 、LiFePO 4 、LiNiPO 4 、LiCoFSO 4 、CuS 2 、FeS 2 、MoS 2 、NiS、TiS 2 And the like. The positive electrode active material may be further modified, and the method of modifying the positive electrode active material is known to those skilled in the art, for example, the positive electrode active material may be modified by coating, doping, and the like, and the material used in the modification may be one or a combination of more of Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce, W, and the like. And the positive electrode current collector is generally a structure or a part for collecting current, and the positive electrode current collector may be any material suitable for being used as a positive electrode current collector of a lithium ion battery in the field, for example, the positive electrode current collector may include, but is not limited to, a metal foil and the like, and more specifically, may include, but is not limited to, an aluminum foil and the like.
The present invention will be described in further detail with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.
Example 1
A preparation method of the anode material comprises the following steps:
1. step S1, an alkaline silica gel solution (industrial grade, PH 13) of 8.5g is taken, and then 1.56g Na is added 2 And S. In a thermostatic water bath at 50 ℃, simple substance Si is obtained, and the particle size is 55 nm. The resulting silicon was dissolved in a 10 wt.% dilute HF solution for 10min to remove unreacted silica and other impurities formed during the reduction.
2. Step S2, adding the above Si powder 0.6g, PVDF 0.3g, NaCl 30g, and 3g C g 6 H 8 O 7 Dissolving in deionized water, namely, the weight part ratio of the simple substance silicon, the citric acid carbon source, the polyvinylidene fluoride fluorine source and the sodium chloride structure template material is 0.6:0.3:30:3, forming a uniformly mixed solution under the action of a magnetic stirrer, and then placing in a freeze dryer to obtain white powder.
3. And step S3, loading the powder into a porcelain boat, putting the porcelain boat into a tube furnace, and introducing argon or nitrogen to calcine the porcelain boat for 2.5 hours at 500 ℃. And then filtering and washing to neutrality, removing a template NaCl, and then drying in vacuum to obtain the Si @ C-F composite material, namely the cathode material.
Secondly, preparing a negative plate: preparing the prepared negative electrode material, conductive agent superconducting carbon, thickening agent carboxymethylcellulose sodium and binder styrene butadiene rubber into negative electrode slurry according to the mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying and rolling at 85 ℃, coating and drying the negative electrode slurry on the other surface of the copper foil according to the method, performing cold pressing treatment on the pole piece with the negative electrode active material layer coated on the two surfaces of the prepared copper foil, and performing edge cutting, piece cutting and strip dividing to prepare the negative electrode piece.
Thirdly, preparing the positive plate: uniformly mixing an NCM811 positive active substance, a conductive agent, superconducting carbon, a carbon tube and a binder, namely polyvinylidene fluoride according to a mass ratio of 96:2.0:0.5:1.5 to prepare positive slurry, coating the positive slurry on one surface of a current collector aluminum foil, drying and rolling at 85 ℃, coating and drying the positive slurry on the other surface of the aluminum foil according to the method, and then carrying out cold pressing treatment on a pole piece of which the two surfaces of the prepared aluminum foil are coated with positive active substance layers; and (4) trimming, cutting into pieces, slitting, and slitting to obtain the positive plate.
Fourthly, preparing electrolyte: lithium hexafluorophosphate (LiPF) 6 ) Dissolving in a mixed solvent of dimethyl carbonate (DEC), Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and diethyl carbonate (DEC) (the mass ratio of the three is 3:5:2) to obtain the electrolyte.
Fifthly, diaphragm: a polyethylene porous film with a thickness of 7 μm was selected as the separator.
Sixthly, preparing the battery:
and winding the prepared negative plate, the diaphragm and the positive plate into a battery cell, wherein the battery cell capacity is about 5 Ah. The diaphragm is positioned between the adjacent positive plate and negative plate, the positive electrode is led out by aluminum tab spot welding, and the negative electrode is led out by nickel tab spot welding; and then placing the battery core in an aluminum-plastic film shell, baking, injecting the electrolyte, packaging, forming, grading and the like, and finally preparing the lithium ion battery.
Example 2
The difference from example 1 is that: the weight part ratio of the simple substance silicon to the carbon source to the fluorine source to the structure template material is 2:1:20: 4.
The rest is the same as embodiment 1, and the description is omitted here.
Example 3
The difference from example 1 is that: the weight portion ratio of the simple substance silicon to the carbon source to the fluorine source to the structural template material is 0.8:0.8:40: 6.
The rest is the same as embodiment 1, and the description is omitted here.
Example 4
The difference from example 1 is that: the weight part ratio of the simple substance silicon to the carbon source to the fluorine source to the structural template material is 7:5:2: 1.
The rest is the same as embodiment 1, and the description is omitted here.
Example 5
The difference from example 1 is that: the weight part ratio of the simple substance silicon to the carbon source to the fluorine source to the structural template material is 9:3.5:30: 10.
The rest is the same as embodiment 1, and the description is omitted here.
Example 6
The difference from example 1 is that: the weight part ratio of the simple substance silicon to the carbon source to the fluorine source to the structural template material is 1-10: 2-5: 1-6.
The rest is the same as embodiment 1, and the description is omitted here.
Example 7
The difference from example 1 is that: the particle size of the simple substance silicon is 40 nm.
The rest is the same as embodiment 1, and the description is omitted here.
Example 8
The difference from example 1 is that: the particle size of the simple substance silicon is 60 nm.
The rest is the same as embodiment 1, and the description is omitted here.
Example 9
The difference from example 1 is that: the particle size of the simple substance silicon is 80 nm.
The rest is the same as embodiment 1, and the description is omitted here.
Example 10
The difference from example 1 is that: the heating and calcining temperature in the step S3 is 400 ℃, and the reaction time is 3 h.
The rest is the same as embodiment 1, and the description is omitted here.
Example 11
The difference from example 1 is that: the heating and calcining temperature in the step S3 is 600 ℃, and the reaction time is 5 h.
The rest is the same as embodiment 1, and the description is omitted here.
Example 12
The difference from example 1 is that: the heating and calcining temperature in the step S3 is 600 ℃, and the reaction time is 3 h.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 1
A certain mass of basic silica gel solution (technical grade, PH 13) was taken and then 1.56g Na was added 2 And S. Reacting in a constant-temperature water bath at 50 ℃, and then filtering and washing to be neutral to obtain the simple substance Si. The resulting silicon was dissolved in a 10 wt.% dilute HF solution for 10min to remove unreacted silica and other impurities formed during the reduction.
And (3) performance testing:
the above materials (example 1 and comparative example 1) were used as electrode materials, a lithium sheet was used as a counter electrode, and a button lithium ion half cell was assembled in a glove box filled with argon gas together with a separator and an electrolyte. The button cells prepared in the examples and comparative examples were tested for rate capability and cycling performance in an incubator at 25 c, and the results of the electrical performance tests are shown in the table below. In a rate performance test, the gradient currents with current densities of 0.2, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 and 0.2A/g are set, and the Si @ C-F composite electrode material has better rate performance. Secondly, the Si @ C-F electrode material has higher specific capacity and more stable capacity retention rate in a cyclic test of small current of 0.2A/g. Indicating that the volume expansion of the resulting silicon-based material is greatly improved.
Rate capability: TABLE 1
Figure BDA0003706034650000081
Figure BDA0003706034650000091
As can be seen from the table 1, when the Si @ C-F composite anode material and elemental silicon are used as anode materials under the same current density, the Si @ C-F composite anode material has larger gram specific capacity and better rate capability within the current density range of 0.2-2A/g. The Si @ C-F composite negative electrode material silicon and carbon cooperate to provide capacity, so that the prepared material has better specific capacity.
Cycle performance (current density: 0.2A/g): TABLE 2
Figure BDA0003706034650000092
From the table 2, the Si @ C-F composite anode material and the elemental silicon have better cycle performance under the same current density of 0.2A/g, the capacity retention rate is 47.18% after 150 cycles of charge and discharge, and the capacity retention rate is only 22.58% after 60 cycles of charge and discharge in the comparative example 1, so that the Si @ C-F composite anode material has a significant improvement compared with the comparative example 1.
The above examples 1 to 12 and comparative example 1 were subjected to a volume expansion ratio test, and the test results are reported in Table 3.
Testing the thickness expansion rate of the pole piece: at 35 ℃, the lithium ion battery is charged to 4.45V by a 1C constant current, then charged to 0.05C by a constant voltage, and discharged to 3.0V by a 1C constant current, which is the first cycle. The lithium ion battery was cycled 200 times according to the above conditions. And testing the thickness of the pole piece before and after circulation by using a micrometer. The pole piece thickness expansion ratio was calculated by the following formula: the expansion rate of the thickness of the pole piece is [ (thickness after cycle-thickness before cycle)/thickness before cycle ] × 100%.
TABLE 3
Figure BDA0003706034650000093
Figure BDA0003706034650000101
As can be seen from table 3, the Si @ C-F composite negative electrode material of the present invention can effectively solve the volume expansion of silicon after charge and discharge cycles in the negative electrode sheet and the battery, and the volume expansion rate after 200 times of charge and discharge is only 1.3%, which is significantly improved compared to 6.8% in comparative example 1. Moreover, as can be seen from the comparison of examples 1-6, when the weight ratio of the elemental silicon, the carbon source, the fluorine source and the structural template material is set to 0.6:0.3:30:3, the performance of the prepared secondary battery is better. From comparison of examples 1 and 7 to 9, when the particle size of the elemental silicon is set to 55nm, the performance of the prepared secondary battery is better. From comparison of examples 1 and 10 to 12, when the temperature of the heating calcination in the step S3 was set to 500 ℃ and the reaction time was set to 2.5 hours, the performance of the prepared secondary battery was better.
Variations and modifications to the above-described embodiments may also occur to those skilled in the art, which fall within the scope of the invention as disclosed and taught herein. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (10)

1. The preparation method of the anode material is characterized by comprising the following steps of:
step S1, mixing the silica gel solution with sodium sulfide, heating for reaction, filtering and washing, and removing impurities to obtain simple substance silicon;
step S2, adding the simple substance silicon, a carbon source, a fluorine source and a structure template material into a solvent, mixing, and freeze-drying to obtain a powder body;
and step S3, heating and calcining the powder body in inert gas to obtain the Si @ C-F composite material, namely the cathode material.
2. The method for preparing the negative electrode material of claim 1, wherein the weight ratio of the silica gel solution to the sodium sulfide in the step S1 is 2-10: 0.2-5.
3. The preparation method of the anode material according to claim 1 or 2, wherein the heating reaction temperature in the step S1 is 30-60 ℃, and the reaction time is 0.5-2 h.
4. The method for preparing the anode material of claim 1, wherein the ratio of the elemental silicon, the carbon source, the fluorine source and the structural template material in the step S2 is 0.1-10: 0.1-5: 5-80: 0.5-12 by weight.
5. The preparation method of the anode material as claimed in claim 1 or 4, wherein the particle size of the elemental silicon is 40-80 nm.
6. The method for preparing the anode material according to claim 1, wherein the step S1 of removing impurities specifically includes immersing the obtained silicon material in a hydrogen fluoride solution, filtering, and drying to obtain elemental silicon.
7. The method for preparing the anode material according to claim 1, wherein the heating and calcining in the step S3 are performed at 400-600 ℃ for 1-5 hours.
8. A negative electrode material obtained by the method for producing a negative electrode material according to any one of claims 1 to 7.
9. A negative electrode sheet comprising the negative electrode material according to claim 8.
10. A secondary battery comprising the negative electrode sheet according to claim 9.
CN202210705433.1A 2022-06-21 2022-06-21 Negative electrode material, preparation method thereof, negative electrode plate and secondary battery Pending CN115101731A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115799474A (en) * 2022-12-13 2023-03-14 大连理工大学 Preparation method and application of fluorinated silicon-carbon negative electrode material

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115799474A (en) * 2022-12-13 2023-03-14 大连理工大学 Preparation method and application of fluorinated silicon-carbon negative electrode material

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