CN116632203A - Preparation method of silicon anode material for three-dimensional graphene in-situ growth lithium battery, anode material and application of anode material - Google Patents
Preparation method of silicon anode material for three-dimensional graphene in-situ growth lithium battery, anode material and application of anode material Download PDFInfo
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- 238000011065 in-situ storage Methods 0.000 title claims abstract description 27
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 26
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 26
- 239000010703 silicon Substances 0.000 title claims abstract description 26
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 22
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 22
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Classifications
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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
- H01M4/366—Composites as layered products
-
- 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
- H01M4/36—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
-
- 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
- H01M4/625—Carbon or graphite
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a preparation method of a silicon anode material for a three-dimensional graphene in-situ growth lithium battery, which comprises the following steps: uniformly mixing nano silicon particles and three-dimensional graphene particles, and then adding a dispersing agent for mixing; then adding solvent step by step to mix, and kneading; continuously adding solvent for mixing, and performing slurry forming processing; grinding and mixing for the second time; adding an organic carbon source, and carrying out secondary grinding, mixing and cladding; then spray drying treatment is carried out to obtain nano silicon particle groups which are coated by organic carbon sources and take three-dimensional graphene as a framework; sintering under the protection of inert gas, and coating an organic carbon source on the surface of the material to perform thermal cracking reaction to generate amorphous carbon; and crushing and sieving to obtain the three-dimensional graphene in-situ grown nano silicon particles. The three-dimensional graphene in-situ grown nano silicon particles prepared by the method can be used as a lithium battery negative electrode material, can greatly prolong the service life of a battery, and can obviously improve the cycle performance and the low-temperature performance.
Description
Technical Field
The invention relates to the technical field of energy storage material production, in particular to a preparation method of a silicon anode material for a three-dimensional graphene in-situ growth lithium battery, the anode material and application thereof.
Background
Lithium ion batteries have been widely used in recent years due to their excellent performance. At present, a graphite structural material is mainly adopted as a negative electrode material of the lithium ion battery, and the graphite material has the advantages of lower cost, excellent performance and the like, but along with the higher requirement of the market on energy density, the disadvantage of lower energy density of the graphite material is particularly remarkable in the utilization of part of fields.
Silicon can be used as a basis for the negative electrode material of the lithium ion battery, and has the following advantages:
1) Silicon can form Li4.4Si alloy with lithium, and the theoretical lithium storage specific capacity is up to 4200mAh/g (10 times of the analog capacity of graphite);
2) The lithium intercalation potential (0.5V) of silicon is slightly higher than that of graphite, so that lithium dendrite is difficult to form during charging;
3) The silicon has low reactivity with the electrolyte, and the co-intercalation phenomenon of the organic solvent can not occur.
However, silicon also has disadvantages as a negative electrode material for lithium ion batteries. Silicon is a semiconductor material with itself low electrical conductivity. In the electrochemical circulation process, the lithium ions are inserted and separated to expand and contract the volume of the material by more than 300%, the generated mechanical force can gradually pulverize the material to cause structural collapse, and finally, the electrode active material is separated from the current collector to lose electrical contact, so that the cycle performance of the battery is greatly reduced. In addition, due to this volume effect, silicon has difficulty in forming a stable Solid Electrolyte Interface (SEI) film in an electrolyte. With the destruction of the electrode structure, new SEI films are continuously formed on the exposed silicon surface, and corrosion and capacity fading of silicon are aggravated.
Disclosure of Invention
The invention aims to provide a preparation method of a silicon cathode material for a lithium battery grown in situ by three-dimensional graphene, wherein a silicon material is grown in situ in holes of a three-dimensional multilayer structure of the three-dimensional graphene, and the grown silicon material is coated by the graphene, so that expansion and pulverization of the silicon material can be inhibited, and the silicon cathode material can be used as the cathode material of the lithium battery, so that the service life of the battery can be greatly prolonged, and the cycle performance and the low-temperature performance can be remarkably improved.
The invention further aims to provide the silicon anode material for the three-dimensional graphene in-situ growth lithium battery, which is prepared by the method.
The invention further aims to provide application of the three-dimensional graphene in-situ growth silicon anode material for lithium batteries.
In order to achieve the technical effects, the invention adopts the following technical scheme:
a preparation method of a silicon anode material for a three-dimensional graphene in-situ growth lithium battery comprises the following steps:
s1: uniformly mixing nano silicon particles and three-dimensional graphene particles, and then adding a dispersing agent for mixing;
s2: adding solvent into the mixture of the step S1 step by step for mixing, and kneading;
s3: continuously adding solvent for mixing in S2, and performing slurry forming processing;
s4: grinding and mixing the slurry of the step S3 for the first time;
s5: adding an organic carbon source into the slurry of the step S4, and carrying out secondary grinding, mixing and coating;
s6: carrying out spray drying treatment on the mixed solution of the S5 to obtain nano silicon particle groups which are coated by an organic carbon source and take three-dimensional graphene as a framework;
s7: sintering the nano silicon particle group obtained in the step S6 under the protection of inert gas, and coating an organic carbon source on the surface of the nano silicon particle group to perform thermal cracking reaction to generate amorphous carbon;
s8: and S7, crushing and sieving the sinter to obtain the three-dimensional graphene in-situ grown nano silicon particles.
In a specific embodiment, the nano-silicon particles in step S1 have a particle size of 50nm to 500nm; the three-dimensional graphene particles are of a three-dimensional structure, the particle size is 1-10 mu m, the specific surface area is 500-2500 square meters per gram, and the pore size is 10nm-2 mu m.
In a specific embodiment, the mixing device in step S1 is selected from any one of a double planetary mixer, a kneader, and an internal mixer; preferably, the dispersant is water or an oil-based dispersant, preferably water.
In a preferred embodiment, the mass ratio of the nano silicon particles, the three-dimensional graphene particles and the dispersing agent in the step S1 is 60% -90%:8% -30%:2% -10% of the total mass is 100 parts.
In a specific embodiment, the solvent in the step S2 is water or an organic solvent, and the kneading process kneads the solid mixture of S1 into a mud-like kneaded material; preferably, the solvent is added in a total amount of 50-100 parts.
In a specific embodiment, 50-150 parts of solvent is added in step S3, and mixed to form a mixed slurry.
In a specific embodiment, the organic carbon source in the step S5 is one or a combination of more than two of lactose, glucose, sucrose and polyethylene glycol; preferably, the organic carbon source is added in an amount of 1 to 10 parts.
In a specific embodiment, the sintering temperature in the step S7 is 650 to 950 ℃ and the sintering time is 6 to 36 hours.
In a specific embodiment, the particle size obtained by sieving in the step S8 is 1 μm to 10. Mu.m.
On the other hand, the three-dimensional graphene prepared by the preparation method grows a silicon anode material for a lithium battery in situ.
In still another aspect, the three-dimensional graphene in-situ growth silicon anode material for lithium batteries prepared by the preparation method is applied to the lithium battery anode material.
Compared with the prior art, the invention has the following beneficial effects:
according to the preparation method, the silicon material grows in situ in the holes of the three-dimensional multilayer structure of the three-dimensional graphene, the grown silicon material is coated by the graphene, so that the expansion and pulverization of the silicon material can be restrained, even if the silicon material is pulverized, the silicon material is coated by the graphene and cannot undergo a separation reaction, and the capacity can be continuously provided, so that the service life of the battery is greatly prolonged.
In the negative electrode material, the three-dimensional graphene has ultrahigh conductivity, and can be used as a carrier to greatly improve the conductivity of a growth material, so that the power density of the growth material is greatly improved, and the cycle performance and the low-temperature performance of the growth material are obviously improved. The three-dimensional graphene has porosity, so that the three-dimensional graphene has excellent adsorption capacity, can well load other materials, and provides a foundation for in-situ growth. The high specific surface area of the three-dimensional graphene can form an electric double layer reaction in the holes which are not grown, so that the pulse performance of the material is greatly improved, and the response speed of the device is improved.
Detailed Description
The following examples will further illustrate the method provided by the present invention for a better understanding of the technical solution of the present invention, but the present invention is not limited to the examples listed but should also include any other known modifications within the scope of the claims of the present invention.
The patent provides a preparation method of a three-dimensional graphene in-situ growth silicon anode, which comprises the following specific steps:
s1: uniformly mixing nano silicon particles and three-dimensional graphene particles by using mixing equipment, and then adding a dispersing agent for mixing;
s2: step-by-step adding solvent into the S1 solid mixture for mixing, and kneading;
s3: continuously adding solvent for mixing in S2, and performing slurry forming processing
S4: grinding and mixing the slurry S3 for the first time;
s5: adding an organic carbon source into the slurry S4, and carrying out secondary grinding, mixing and coating;
s6, carrying out spray drying treatment on the mixed solution of S5 to obtain nano silicon particle groups which are coated by an organic carbon source and take three-dimensional graphene as a framework;
s7: sintering the obtained S6 nano silicon particle group under the protection of inert gas, and coating an organic carbon source on the surface of the S6 nano silicon particle group to perform thermal cracking reaction to generate amorphous carbon;
s8, crushing and sieving the S7 sinter to obtain the three-dimensional graphene in-situ grown nano silicon particles required by the invention.
In step S1, the nano-silicon particles have a particle size of 50nm to 500nm, including, for example, but not limited to, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc. The three-dimensional graphene particles are three-dimensional structures, have a particle size of 1 μm to 10 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc., a specific surface area of 500 to 2500 square meters/g, for example, 500 square meters/g, 1000 square meters/g, 1500 square meters/g, 2000 square meters/g, 2500 square meters/g, etc., and a pore size of 10nm to 2 μm, for example, including but not limited to 10nm, 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1 μm, 2 μm, etc.
In step S1, the dispersing agent is water or an organic solvent, for example NMP, preferably water, in order that each solid material is more compatible with the solvent, and is selected according to the solubility. The mass ratio of the nano silicon particles to the three-dimensional graphene particles to the dispersing agent is (60% -90%): (8% -30%): (2% -10%), the total mass is 100 parts, and these 100 parts by mass are added as a basis for the subsequent addition of other solvents and the like, for example, 60%:10%:2% or 70%:20%:5% or 80%:30%:8% or 90%:30%:10% or 70%:30%:5%, etc., but is not limited thereto.
In step S1, the mixing apparatus may be a mixing apparatus commonly used in the art, and is not particularly limited, for example, a twin planetary mixer, a kneader, an internal mixer, etc., and the mixing time is not particularly limited, so long as the three are substantially uniformly mixed.
In the step S2, the added solvent can be water or an organic solvent; preferably, the same dispersant as in step S1, for example, is water. The solvent is added step by step, for example, in three or more parts by volume or mass, and finally 50 to 100 parts of the solvent is added, and the mixture of S1 is kneaded by step addition of the solvent based on 100 parts by mass of the total of the nano silicon particles, the three-dimensional graphene particles and the dispersing agent to form a mud-like kneaded material.
In step S3, solvent is continuously added for mixing, and the slurry is formed by processing. The solvent added can be water or organic solvent; preferably, the same dispersant as in step S1, for example, is water. And adding 50-150 parts by mass of solvent, and mixing to form mixed slurry based on 100 parts by mass of the total mass of the nano silicon particles, the three-dimensional graphene particles and the dispersing agent.
In step S4, the slurry of S3 is subjected to primary grinding and mixing. The grinding and mixing are used for better adsorbing nano silicon on the surface of the three-dimensional graphene, and the grinding and mixing equipment is not particularly limited, and can be grinding equipment commonly used in the field, for example, the grinding time is 3-20h.
In step S5, adding an organic carbon source into the slurry in step S4, and carrying out secondary grinding, mixing and coating. The organic carbon source is, for example, one or a combination of two or more of lactose, glucose, sucrose, polyethylene glycol, etc.; the addition amount of the organic carbon source is 1-10 parts (based on 100 parts of the total mass of the nano silicon particles, the three-dimensional graphene particles and the dispersing agent). The secondary milling and mixing time is, for example, 3 to 20 hours.
In the step S6, the mixed solution of the step S5 is subjected to spray drying treatment to obtain the nano silicon particle group which is coated by the organic carbon source and takes the three-dimensional graphene as the framework. Among them, the spray drying treatment is not particularly limited, and is a conventional means in the art, as long as it is a prior art. The particle size of the obtained nano silicon particle group which takes the three-dimensional graphene as the framework and is coated by the organic carbon source is 1 μm to 10 μm.
In step S7, the nano-silicon particle clusters obtained in step S6 are sintered under an inert gas protection atmosphere, wherein the inert gas is, for example, nitrogen, the sintering temperature is 650-950 ℃, for example, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃, 900 ℃, 950 ℃ and the like, and the sintering time is 6-36 h, for example, 6h, 10h, 15h, 20h, 25h, 30h, 36h and the like; and carrying out thermal cracking reaction on the organic carbon source coated on the surfaces of the nano silicon particle groups through sintering treatment to generate amorphous carbon.
In step S8, the S7 sinter is crushed and sieved to obtain three-dimensional graphene in-situ grown nano-silicon particles, wherein the particle size of the particles can be 1-10 μm, such as but not limited to 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm and 10 μm.
According to the three-dimensional graphene in-situ growth nano silicon particles prepared by the preparation method, the silicon material is grown in situ in the holes of the three-dimensional multilayer structure of the three-dimensional graphene, and the grown silicon material is coated by the graphene, so that the expansion and pulverization of the silicon material can be inhibited.
The invention is further illustrated by the following examples, which are not intended to limit the invention in any way.
Example 1
1) 80 parts of nano silicon particles, 15 parts of three-dimensional graphene and 5 parts of dispersing agent water are weighed and added into a kneader to be uniformly mixed. Wherein the particle size of the nano silicon particles is 100nm; the particle size of the three-dimensional graphene is 2 mu m, and the specific surface area is about 1500 square meters per gram.
2) 100 parts of ultrapure water was weighed and fed into a kneader in portions, and high-speed kneading was performed for a period of 6 hours, and the final state was a mud-like state.
3) Transferring the mud-like material into a double planetary mixer, weighing 100 parts of ultrapure water, adding, and stirring at high speed for 6h to obtain the final slurry.
4) The slurry was transferred to a grinder for grinding for 6 hours.
5) 8 parts of lactose is added, secondary grinding is carried out for 6 hours, mixing and coating are carried out, and mixed liquid is obtained.
6) And carrying out spray drying treatment on the mixed solution to obtain the nano silicon particle group which is coated by the organic carbon source and takes the three-dimensional graphene as a framework.
7) Sintering the nano silicon particle group for 24 hours at 800 ℃ in a nitrogen gas protection atmosphere, and coating the surface of the nano silicon particle group to generate amorphous carbon.
8) The powder was crushed by an air jet mill and the particle size was controlled to 2. Mu.m.
9) The three-dimensional graphene silicon carbon material, the adhesive CMC and the adhesive SBR are mixed according to the following proportion of 96: mixing the materials according to the mass ratio of 1.6:2.4 to prepare slurry, coating, rolling and slitting the slurry to prepare an electrode, and packaging the electrode with a positive electrode, a diaphragm, a structural member, electrolyte and the like to obtain the 18650 battery cell.
Example 2
1) 90 parts of nano silicon particles, 8 parts of three-dimensional graphene and 2 parts of dispersing agent NMP are weighed and added into a kneader to be uniformly mixed. Wherein the particle size of the nano silicon particles is 100nm; the particle size of the three-dimensional graphene is 2 mu m, and the specific surface area is about 1500 square meters per gram.
2) 100 parts of ultrapure water was weighed and fed into a kneader in portions, and high-speed kneading was performed for a period of 6 hours, and the final state was a mud-like state.
3) Transferring the mud-like material into a double planetary mixer, weighing 100 parts of ultrapure water, adding, and stirring at high speed for 6h to obtain the final slurry.
4) The slurry was transferred to a grinder for grinding for 6 hours.
5) Lactose 2 parts is added, secondary grinding is carried out for 6 hours, mixing and coating are carried out, and mixed liquid is obtained.
6) And carrying out spray drying treatment on the mixed solution to obtain the nano silicon particle group which is coated by the organic carbon source and takes the three-dimensional graphene as a framework.
7) Sintering the nano silicon particle group for 24 hours at 800 ℃ in a nitrogen gas protection atmosphere, and coating the surface of the nano silicon particle group to generate amorphous carbon.
8) The powder was crushed by an air jet mill and the particle size was controlled to 2. Mu.m.
9) The three-dimensional graphene silicon carbon material, the adhesive CMC and the adhesive SBR are mixed according to the following proportion of 96: mixing the materials according to the mass ratio of 1.6:2.4 to prepare slurry, coating, rolling and slitting the slurry to prepare an electrode, and packaging the electrode with a positive electrode, a diaphragm, a structural member, electrolyte and the like to obtain the 18650 battery cell.
Example 3
1) 60 parts of nano silicon particles, 30 parts of three-dimensional graphene and 10 parts of dispersing agent water are weighed and added into a kneader to be uniformly mixed. Wherein the particle size of the nano silicon particles is 100nm; the particle size of the three-dimensional graphene is 2 mu m, and the specific surface area is about 1500 square meters per gram.
2) 100 parts of ultrapure water was weighed and fed into a kneader in portions, and high-speed kneading was performed for a period of 6 hours, and the final state was a mud-like state.
3) Transferring the mud-like material into a double planetary mixer, weighing 100 parts of ultrapure water, adding, and stirring at high speed for 6h to obtain the final slurry.
4) The slurry was transferred to a grinder for grinding for 6 hours.
5) 8 parts of lactose is added, secondary grinding is carried out for 6 hours, mixing and coating are carried out, and mixed liquid is obtained.
6) And carrying out spray drying treatment on the mixed solution to obtain the nano silicon particle group which is coated by the organic carbon source and takes the three-dimensional graphene as a framework.
7) Sintering the nano silicon particle group for 24 hours at 800 ℃ in a nitrogen gas protection atmosphere, and coating the surface of the nano silicon particle group to generate amorphous carbon.
8) The powder was crushed by an air jet mill and the particle size was controlled to 2. Mu.m.
9) The three-dimensional graphene silicon carbon material, the adhesive CMC and the adhesive SBR are mixed according to the following proportion of 96: mixing the materials according to the mass ratio of 1.6:2.4 to prepare slurry, coating, rolling and slitting the slurry to prepare an electrode, and packaging the electrode with a positive electrode, a diaphragm, a structural member, electrolyte and the like to obtain the 18650 battery cell.
Comparative example 1
Directly using 200nm silicon material to prepare 18650 cell.
Comparative example 2
The only difference compared to example 1 is that graphite material is used instead of three-dimensional graphene.
Comparative example 3
The only difference compared to example 1 is that porous carbon material is used instead of three-dimensional graphene.
Comparative example 4
The only difference compared to example 1 is that a two-dimensional graphene material is used instead of three-dimensional graphene.
Test group 1
The materials of the above examples and comparative examples were subjected to powder resistance test, and the results are shown in table 1.
The powder resistance test method comprises the following steps: 1g of the powder materials of the examples and the comparative examples are weighed, placed into a measuring jig, the jig is placed into a pre-compaction device, the pre-compaction device is started to compact for 15 seconds, the jig is placed back into the powder resistivity device starting software to start testing, and the tested powder resistances are shown in table 1.
Table 1 powder resistance of example and comparative powder materials
| Powder resistor (KΩ/cm) | |
| Example 1 | 18.65 |
| Example 2 | 26.49 |
| Example 3 | 13.87 |
| Comparative example 1 | 259.84 |
| Comparative example 2 | 158.36 |
| Comparative example 3 | 188.37 |
| Comparative example 4 | 29.47 |
From the powder resistance test results of table 1, it can be seen that:
of the three examples, example 3 had a higher three-dimensional graphene content, so it had a lower resistivity, indicating that it had a higher rate capability.
As can be seen from the comparison of example 1 and comparative examples 1 to 4, the same amount of the additive, the present invention has lower resistivity and higher rate capability.
Test group 2
The batteries assembled in examples 1 to 3 and comparative examples 1 to 4 were subjected to a rate test and a cycle life test, and the battery cells after the cycle life test were subjected to an anatomical analysis, and the results are shown in table 2.
Table 2 test of battery performance assembled in examples and comparative examples
From the battery performance test data in table 2, the three-dimensional graphene in-situ grown silicon anode material has better multiplying power performance and cycle performance.
While the present invention has been described in detail through the foregoing description of the preferred embodiment, it should be understood that the foregoing description is not to be considered as limiting the invention. Those skilled in the art will appreciate that certain modifications and adaptations of the invention are possible and can be made under the teaching of the present specification. Such modifications and adaptations are intended to be within the scope of the present invention as defined in the appended claims.
Claims (10)
1. The preparation method of the silicon anode material for the three-dimensional graphene in-situ growth lithium battery is characterized by comprising the following steps of:
s1: uniformly mixing nano silicon particles and three-dimensional graphene particles, and then adding a dispersing agent for mixing;
s2: adding solvent into the mixture of the step S1 step by step for mixing, and kneading;
s3: continuously adding solvent for mixing in S2, and performing slurry forming processing;
s4: grinding and mixing the slurry of the step S3 for the first time;
s5: adding an organic carbon source into the slurry of the step S4, and carrying out secondary grinding, mixing and coating;
s6: carrying out spray drying treatment on the mixed solution of the S5 to obtain nano silicon particle groups which are coated by an organic carbon source and take three-dimensional graphene as a framework;
s7: sintering the nano silicon particle group obtained in the step S6 under the protection of inert gas, and coating an organic carbon source on the surface of the nano silicon particle group to perform thermal cracking reaction to generate amorphous carbon;
s8: and S7, crushing and sieving the sinter to obtain the three-dimensional graphene in-situ grown nano silicon particles.
2. The method according to claim 1, wherein the nano-silicon particles in the step S1 have a particle size of 50nm to 500nm; the three-dimensional graphene particles are of a three-dimensional structure, the particle size is 1-10 mu m, the specific surface area is 500-2500 square meters per gram, and the pore size is 10nm-2 mu m.
3. The preparation method according to claim 1, wherein the mixing equipment in the step S1 is selected from any one of a double planetary mixer, a kneader, and an internal mixer; preferably, the dispersant is water or an oil-based dispersant, preferably water.
4. A method according to any one of claims 1 to 3, wherein the mass ratio of the nano silicon particles, the three-dimensional graphene particles and the dispersant in step S1 is 60% -90%:8% -30%:2% -10% of the total mass is 100 parts.
5. The method according to claim 1, wherein the solvent in the step S2 is water or an organic solvent, and the kneading process kneads the solid mixture of S1 into a slurry-like kneaded material; preferably, the solvent is added in an amount of 50 to 100 parts by mass.
6. The method according to claim 1, wherein 50-150 parts of the solvent is added in the step S3, and the mixture is mixed to form a mixed slurry.
7. The preparation method according to claim 1, wherein the organic carbon source in the step S5 is one or a combination of more than two of lactose, glucose, sucrose and polyethylene glycol; preferably, the organic carbon source is added in an amount of 1 to 10 parts.
8. The method according to claim 1, wherein the sintering temperature in the step S7 is 650-950 ℃ and the sintering time is 6-36 h; preferably, the particle size obtained by sieving in the step S8 is 1 μm to 10. Mu.m.
9. The silicon negative electrode material for a three-dimensional graphene in-situ growth lithium battery prepared by the preparation method of any one of claims 1 to 8.
10. The silicon negative electrode material for a three-dimensional graphene in-situ growth lithium battery prepared by the preparation method of any one of claims 1 to 8 or the application of the silicon negative electrode material for a three-dimensional graphene in-situ growth lithium battery in the negative electrode material of a lithium battery.
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