CN111900353B - Composite material, preparation method, lithium ion battery negative electrode material containing composite material and lithium ion battery - Google Patents
Composite material, preparation method, lithium ion battery negative electrode material containing composite material and lithium ion battery Download PDFInfo
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- CN111900353B CN111900353B CN202010754555.0A CN202010754555A CN111900353B CN 111900353 B CN111900353 B CN 111900353B CN 202010754555 A CN202010754555 A CN 202010754555A CN 111900353 B CN111900353 B CN 111900353B
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- H01—ELECTRIC ELEMENTS
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- 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
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- 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
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
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- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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- 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
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- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2220/00—Batteries for particular applications
- H01M2220/10—Batteries in stationary systems, e.g. emergency power source in plant
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- H—ELECTRICITY
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2220/00—Batteries for particular applications
- H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2220/00—Batteries for particular applications
- H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
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- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a composite material, a preparation method thereof, a lithium ion battery cathode material containing the composite material and a lithium ion battery, and relates to the technical field of new materials or energy storage materials. The composite material is mainly composed of at least one layer of nano silicon layer and at least one layer of nano carbon layer coated on the surface of the inner core; the nano silicon layer and the nano carbon layer are different in two adjacent layers in the composite material, and the nano carbon layer is arranged on the outermost layer of the composite material. By the arrangement of the layered structure, the problem of volume expansion of silicon in the processes of lithium ion intercalation and deintercalation is effectively solved while the energy density of the composite material is improved by adding the nano-silicon raw material; and above-mentioned nanometer carbon layer sets up in the outermost setting of combined material, also can effectively protect the nanometer silicon layer of this application not with electrolyte direct contact, and then has also alleviated current nanometer silicon material and the unstable poor problem of cycle performance that leads to after lithium ion battery electrolyte contacts.
Description
Technical Field
The invention relates to the technical field of new materials or energy storage materials, in particular to a composite material, a preparation method, a lithium ion battery cathode material containing the composite material and a lithium ion battery.
Background
The lithium ion secondary battery is an electronic device which can allow charging and discharging by combining with components such as a diaphragm, an electrolyte, a battery shell and the like by utilizing the property that positive and negative electrode materials allow lithium ions to be inserted and extracted. The amount of positive and negative electrode materials that can allow intercalation and deintercalation of lithium ions determines the capacity of the positive and negative electrode materials and the lithium ion secondary battery. In recent years, with the rapid development of lithium ion secondary batteries, the lithium ion secondary batteries have been widely applied to electronic consumption, power transportation, and energy storage devices such as mobile phones, computers, wearable devices, electric vehicles, and buses, and particularly, in recent years, with the rapid development of mobile phones and electric vehicles, new requirements for weight and endurance of the lithium ion secondary batteries have been made.
The current commercialized lithium ion battery cathode materials are carbon cathode materials, mainly artificial graphite and natural graphite, and a part of hard carbon and soft carbon materials, and in addition, a part of lithium titanate materials. The theoretical capacity of the carbon negative electrode material is 372 mAh/g; meanwhile, the tin alloy, silicon and oxides thereof and the silicon alloy which are widely concerned at present have higher theoretical capacity, particularly silicon materials, the theoretical capacity of silicon is up to 4200mAh/g, which is ten times that of carbon negative electrode materials, and the tin alloy, the silicon and oxides thereof and the silicon alloy have good application prospect. Although the theoretical capacity of silicon is high, silicon undergoes a large volume change during the intercalation and deintercalation of lithium ions.
Therefore, most of the current silicon-based negative electrode materials are that the size of silicon is reduced, so that the volume effect in the process of lithium ion insertion and removal of silicon is reduced, or a barrier layer is coated on the outer layer of micron silicon, so that the opportunity that the silicon surface is in direct contact with electrolyte is reduced, and the cycle performance of the material is more stable. However, for preparing micron silicon and even nanometer silicon with high purity and small particle size, the small-particle silicon powder is generally obtained by adopting crushing modes such as ball milling, sanding and the like, so that the energy consumption is very high, and the industrial production is not facilitated; or the nano silicon is obtained in a gas phase mode, and then the silicon powder is mixed with other materials to prepare the silicon-carbon composite material, the dispersion technology of the micron silicon or the nano silicon in the composite process is very critical, the composite material with uniform dispersion is difficult to obtain, and the micron silicon or the nano silicon is extremely easy to oxidize in the preparation, storage and use processes, so that the performance of the material is reduced and the negative effects of instability are caused.
Therefore, in view of the problem that the application of the existing silicon-based materials in the negative electrode materials of the lithium ion batteries is not ideal, it has become necessary and urgent to research and develop a silicon-based negative electrode material of the lithium ion batteries with high energy density and stable cycle performance so as to alleviate the above problems of the existing silicon-based negative electrode materials of the lithium ion batteries.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a composite material, which effectively solves the problems of volume expansion of silicon in the processes of lithium ion intercalation and deintercalation and poor cycle performance caused by instability of the existing nano-silicon material after the existing nano-silicon material is contacted with lithium ion battery electrolyte.
The second purpose of the invention is to provide a preparation method of the composite material.
The third purpose of the invention is to provide a lithium ion battery cathode material which has the advantages of high energy density and stable cycle performance, and effectively solves the problems of low energy density and poor cycle performance of the conventional silicon-containing lithium ion battery cathode material.
The fourth purpose of the invention is to provide a lithium ion battery, which comprises the lithium ion battery negative electrode material.
A fifth object of the present invention is to provide an electronic device, an electric tool, an electric vehicle, or an electric power storage system including the lithium ion battery described above.
The composite material provided by the invention mainly comprises at least one layer of nano silicon layer and at least one layer of nano carbon layer coated on the surface of an inner core;
the nano silicon layer and the nano carbon layer are different in two adjacent layers in the composite material, and the nano carbon layer is arranged on the outermost layer of the composite material;
the inner core comprises a solid inner core and/or a hollow inner core, and the solid inner core is mainly composed of a matrix material.
Furthermore, in the composite material, the average particle size of the matrix material is 0.01-30 μm, preferably 0.05-20 μm;
furthermore, in the composite material, the average particle size of the matrix material is 0.01-5 μm, preferably 0.03-3 μm, and more preferably 0.05-1 μm.
Preferably, the matrix material includes any one of natural graphite, artificial graphite, expanded graphite, hard carbon, soft carbon, mesocarbon microbeads, petroleum coke, carbon fibers, pyrolytic resin carbon, carbon black, carbon nanotubes, graphene, tin oxide, tin composite oxide, silicon monoxide, titanium dioxide, silicon dioxide, calcium oxide, calcium carbonate, aluminum oxide, magnesium oxide, or magnesium carbonate.
Further, the thickness of the nano silicon layer is 1-1000 nm, preferably 5-200 nm;
the thickness of the nano carbon layer is 1-100 nm, preferably 2-50 nm.
Further, the composite material sequentially comprises from inside to outside: a solid core, a nano silicon layer and a nano carbon layer;
preferably, the composite material comprises, in order from inside to outside: the solid core, the first nano silicon layer, the first nano carbon layer, the second nano silicon layer and the second nano carbon layer;
preferably, the composite material comprises, in order from inside to outside: the hollow core, the first nano carbon layer, the first nano silicon layer and the second nano carbon layer.
The invention provides a preparation method of the composite material, which comprises the following steps:
providing a solid core, and then coating at least one layer of nano silicon layer and at least one layer of nano carbon layer on the surface of the solid core to obtain a composite material; the adjacent two layers of the nano silicon layer and the nano carbon layer in the composite material are different, and the nano carbon layer is arranged on the outermost layer of the composite material;
optionally, the step of removing the solid core to prepare the hollow core comprises: dissolving a matrix material by using an acid solution, and then calcining to prepare a hollow composite material not containing the matrix material;
the specific method comprises the following steps: uniformly mixing the composite material with an acid solution or an alkali solution, then carrying out solid-liquid separation, removing the residual solution through washing and filtering, and finally obtaining the liquid-free composite material with the hollow core in a drying or roasting mode;
preferably, the nano silicon layer is coated by adopting a vapor deposition method;
preferably, the nano carbon layer is coated by any one of vapor deposition, liquid phase coating or solid phase coating.
Preferably, the acid solution used for removing the solid core to prepare the hollow core is one or a mixture of more than two of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, formic acid and acetic acid;
preferably, the alkali solution used for removing the solid core to prepare the hollow core is one or a mixture of more than two of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia water, sodium amide and sodium methoxide;
the invention provides a lithium ion battery negative electrode material containing the composite material.
Further, the lithium ion battery negative electrode material comprises a negative electrode material A, a negative electrode material B and a negative electrode material C;
wherein: the negative electrode material A is the composite material;
the negative electrode material B is mainly prepared by mixing the negative electrode material A and auxiliary materials and then drying;
the negative electrode material C comprises a negative electrode material B and a nano carbon layer a, and the nano carbon layer a is coated on the surface of the negative electrode material B.
Preferably, the negative electrode material C comprises a negative electrode material B and a nano silicon carbide layer, and the nano silicon carbide layer is coated on the surface of the negative electrode material B.
Further, the average particle size of the negative electrode material B is 2-50 μm, preferably 4-30 μm;
preferably, in the negative electrode material B, the mass ratio of the negative electrode material A to the auxiliary material is 1: 0.02-0.6, and preferably 1: 0.05-0.4;
preferably, the auxiliary materials comprise a filler and a binder;
more preferably, the filler comprises at least one of microcrystalline graphite, small flake graphite, earthy graphite, expanded graphite, carbon nanotubes, graphene and carbon black;
more preferably, the binder comprises at least one of phenolic resin, coal tar, pitch, sucrose, fructose, sodium hydroxymethyl cellulose, starch, polyvinyl chloride, polyvinyl pyrrolidone, and polyvinylidene fluoride.
Further, in the negative electrode material C, the thickness of the nano carbon layer a is 1-500 nm, preferably 2-200 nm;
preferably, in the negative electrode material C, the thickness of the nano silicon carbide layer is 1-500 nm, and preferably 2-200 nm.
The invention provides a lithium ion battery which comprises the lithium ion battery cathode material.
The invention provides an electronic device, an electric tool, an electric vehicle or a power storage system comprising the lithium ion battery.
Compared with the prior art, the invention has the beneficial effects that:
the composite material provided by the invention mainly comprises at least one layer of nano silicon layer and at least one layer of nano carbon layer coated on the surface of an inner core; the nano silicon layer and the nano carbon layer are different in two adjacent layers in the composite material, and the nano carbon layer is arranged on the outermost layer of the composite material; the inner core comprises a solid inner core and/or a hollow inner core, and the solid inner core is mainly composed of a matrix material. According to the invention, through the arrangement of the layered structure of the nano silicon layer and the nano carbon layer, the problem of volume expansion of silicon in the process of lithium ion intercalation and deintercalation is effectively relieved while the nano silicon raw material is added to improve the energy density of the composite material; and above-mentioned nanometer carbon layer sets up in the outermost setting of combined material, also can effectively protect the nanometer silicon layer of this application not by electrolyte oxidation, and then has also alleviated current nanometer silicon material and the unstable poor problem of cycle performance that leads to after lithium ion battery electrolyte contacts.
The preparation method of the composite material provided by the invention comprises the steps of providing a solid core, and then coating at least one layer of nano silicon layer and at least one layer of nano carbon layer on the surface of the solid core to obtain the composite material; the adjacent two layers of the nano silicon layer and the nano carbon layer in the composite material are different, and the nano carbon layer is arranged on the outermost layer of the composite material. The preparation method has the advantages of simple preparation process and easy operation.
The lithium ion battery cathode material provided by the invention comprises the composite material. Because the composite material effectively relieves the problems of volume expansion of silicon in the process of embedding and releasing lithium ions and easy oxidation of nano silicon by electrolyte, the lithium ion battery cathode material containing the composite material has the advantages of high energy density and stable cycle performance, and effectively relieves the problems of low energy density and poor cycle performance of the conventional silicon-containing lithium ion battery cathode material.
The lithium ion battery provided by the invention comprises the lithium ion battery cathode material. Because the lithium ion battery cathode material has the advantages of high energy density and stable cycle performance, the lithium ion battery containing the lithium ion battery cathode material can obtain the same effect.
The lithium ion battery provided by the invention can be widely applied to electronic devices, electric tools, electric vehicles or power storage systems, and because the lithium ion battery has the advantages of high energy density and stable cycle performance, the same effect can be obtained in the electronic devices, the electric tools, the electric vehicles and the power storage systems using the lithium ion battery.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a graph of specific capacity effect of different cycle times of the negative electrode materials of the lithium ion batteries prepared in the embodiments 1, 4, 6 and 10 of the present application, provided in the experimental example 1 of the present invention;
fig. 2 is a graph of specific capacity effect of different cycle times of the negative electrode materials of the lithium ion batteries prepared in the embodiments 11 and 12 of the present application, provided in the experimental example 1 of the present invention;
fig. 3 is a graph of specific capacity effect of different cycle times of the negative electrode materials of the lithium ion batteries prepared in comparative example 1 and comparative example 2 of the present application provided in experimental example 1 of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
According to one aspect of the invention, the composite material is mainly composed of at least one nano silicon layer and at least one nano carbon layer coated on the surface of an inner core;
the nano silicon layer and the nano carbon layer are different in two adjacent layers in the composite material, and the nano carbon layer is arranged on the outermost layer of the composite material;
the inner core comprises a solid inner core and/or a hollow inner core, and the solid inner core is mainly composed of a matrix material.
The composite material provided by the invention mainly comprises at least one layer of nano silicon layer and at least one layer of nano carbon layer coated on the surface of an inner core; the nano silicon layer and the nano carbon layer are different in two adjacent layers in the composite material, and the nano carbon layer is arranged on the outermost layer of the composite material; the inner core comprises a solid inner core and/or a hollow inner core, and the solid inner core is mainly composed of a matrix material. According to the invention, through the arrangement of the layered structure of the nano silicon layer and the nano carbon layer, the problem of volume expansion of silicon in the process of lithium ion intercalation and deintercalation is effectively relieved while the nano silicon raw material is added to improve the energy density of the composite material; and above-mentioned nanometer carbon layer sets up in the outermost setting of combined material, also can effectively protect the nanometer silicon layer of this application not by electrolyte oxidation, and then has also alleviated current nanometer silicon material and the unstable poor problem of cycle performance that leads to after lithium ion battery electrolyte contacts.
In a preferred embodiment of the present invention, in the composite material, the average particle size of the matrix material is 0.01 to 30 μm, preferably 0.05 to 20 μm;
in a preferred embodiment of the present invention, the average particle size of the matrix material is 0.01 to 5 μm, preferably 0.03 to 3 μm, and more preferably 0.05 to 1 μm.
As a preferred embodiment, the material with the particle size is used as the matrix, which can be beneficial to the uniform coating of the silicon nano-particles and does not need to be crushed separately after being prepared into a finished product.
Typical but non-limiting preferred embodiments of the above-described average particle size of the matrix material are: 0.01 μm, 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 3 μm, 5 μm, 7 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm and 20 μm, 30 μm.
In a preferred embodiment of the present invention, the matrix material includes any one of natural graphite, artificial graphite, expanded graphite, hard carbon, soft carbon, mesocarbon microbeads, petroleum coke, carbon fibers, pyrolytic resin carbon, carbon black, carbon nanotubes, graphene, tin oxide, tin composite oxide, silicon monoxide, titanium dioxide, silicon dioxide, calcium oxide, calcium carbonate, aluminum oxide, magnesium oxide, or magnesium carbonate.
In a preferred embodiment of the present invention, the thickness of the nano silicon layer is 1 to 1000nm, preferably 5 to 200 nm; the thickness of the nano carbon layer is 1-100 nm, preferably 2-50 nm.
As a preferred embodiment, the thickness of the nano silicon layer can ensure that the material has higher specific capacity, and can control the volume effect of silicon charging and discharging in a reasonable range, thereby greatly reducing the pulverization probability.
Typical but non-limiting preferred embodiments of the thickness of the above-described nanosilicon layer are: 1nm, 5nm, 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm and 1000 nm; typical but non-limiting preferred embodiments of the thickness of the nanocarbon layer described above are: 1nm, 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm and 100 nm.
In a preferred embodiment of the present invention, the composite material comprises, in order from inside to outside: a solid core, a nano silicon layer and a nano carbon layer;
preferably, the composite material comprises, in order from inside to outside: the solid core, the first nano silicon layer, the first nano carbon layer, the second nano silicon layer and the second nano carbon layer;
preferably, the composite material comprises, in order from inside to outside: the hollow core, the first nano carbon layer, the first nano silicon layer and the second nano carbon layer.
According to one aspect of the present invention, a preparation method of the above composite material comprises the following steps:
providing a solid core, and then coating at least one layer of nano silicon layer and at least one layer of nano carbon layer on the surface of the solid core to obtain a composite material; the adjacent two layers of the nano silicon layer and the nano carbon layer in the composite material are different, and the nano carbon layer is arranged on the outermost layer of the composite material;
the preparation method of the composite material provided by the invention comprises the steps of providing a solid core, and then coating at least one layer of nano silicon layer and at least one layer of nano carbon layer on the surface of the solid core to obtain the composite material; the adjacent two layers of the nano silicon layer and the nano carbon layer in the composite material are different, and the nano carbon layer is arranged on the outermost layer of the composite material. The preparation method has the advantages of simple preparation process and easy operation.
In a preferred embodiment of the present invention, optionally, the step of removing the solid core to prepare the hollow core comprises: dissolving the composite material by using an acid solution or an alkali solution, and then calcining to prepare a hollow composite material which does not contain the matrix material;
the specific method comprises the following steps: and mixing and stirring the composite material and an acid solution or an alkali solution to dissolve the solid core in the solution, performing solid-liquid separation by means of filtration and the like, removing the residual solution in the solid by washing and filtration, and finally obtaining the liquid-free composite material with the hollow core by means of drying or roasting.
Preferably, the acid solution used for removing the solid core to prepare the hollow core is one or a mixture of more than two of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, formic acid and acetic acid;
preferably, the alkali solution used for removing the solid core to prepare the hollow core is one or a mixture of more than two of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia water, sodium amide and sodium methoxide;
in a preferred embodiment of the present invention, the nano-silicon layer is coated by a vapor deposition method; the vapor deposition raw material coated by the nano silicon layer comprises any one of monosilane, monochlorohydrogen, dichlorosilane and trichlorosilane, and preferably monosilane and trichlorosilane;
as a preferred embodiment, the nano-silicon layer is directly prepared on the substrate by a vapor deposition method, compared with the existing methods of grinding and composite deposition of silicon powder and other materials, the method has the advantages of simple preparation process and easily controlled reaction process, and the silicon particles generated by vapor deposition are in a nano-scale.
In the above preferred embodiment, the step (a) of coating the silicon coating layer comprises the steps of: and heating to 450-1200 ℃ in an inert gas atmosphere, and then introducing a vapor deposition raw material coated by the nano silicon layer for deposition to finish coating of the silicon coating layer.
In a preferred embodiment of the present invention, the nano carbon layer is coated by any one of vapor deposition, liquid phase coating or solid phase coating;
in a preferred embodiment of the present invention, the negative electrode material C includes a negative electrode material B and a nano silicon carbide layer, and the nano silicon carbide layer is coated on the surface of the negative electrode material B.
As a preferred embodiment, when the nanocarbon layer is coated using a vapor deposition method, the nanocarbon layer-coated vapor deposition raw material includes any one of hydrocarbon or hydrocarbon-oxygen compound; when the nano silicon carbide layer is coated by using a vapor deposition method, the vapor deposition raw material coated by the nano silicon carbide layer comprises any one of hydrocarbon silane or halohydrocarbon silane;
more preferably, the hydrocarbon compound comprises at least one of methane, ethane, ethylene, propane, propylene, butylene, benzene, toluene, and xylene, and the hydrocarbon oxidized product comprises at least one of methanol, ethanol, propanol, acetone, and cresol; the hydrocarbyl silane comprises tetramethylsilane or hexamethyldisilane; the halohydrocarbyl silane comprises one of trimethylchlorosilane, dimethylchlorosilane or trichloromethylsilane.
Preferably, the method for coating the nano carbon layer by vapor deposition comprises the following steps: and heating to 450-1100 ℃ in an inert gas atmosphere, introducing a vapor deposition raw material coated by the nano carbon layer, and depositing to finish coating of the carbon coating layer.
Preferably, when the liquid phase coating nanocarbon layer is used, the liquid phase coating material includes at least one of coal pitch, petroleum pitch, coal tar, epoxy resin, phenol resin, furan resin, urea resin, melamine resin, and polyformaldehyde resin;
preferably, the method for liquid phase coating of the nano carbon layer comprises the following steps: dissolving a liquid-phase coating material into a solution, wherein the concentration of the coating material in the solution is 0.1-10%, mixing a substrate or a substrate deposited with a silicon layer with the solution, wherein the volume ratio of the substrate deposited with the silicon layer to the solution is 0.2-5: 1, and drying or roasting. Wherein the drying temperature is 50-300 ℃, and the roasting temperature is 500-1250 ℃;
preferably, when the solid-phase coated nanocarbon layer is used, the solid-phase coating material includes at least one of coal pitch, petroleum pitch, epoxy resin, phenol resin, furan resin, urea resin, melamine resin, and polyformaldehyde resin;
preferably, the method for coating the nano carbon layer by the solid phase comprises the following steps: mixing the solid phase coating material with a matrix, and then carrying out ball milling, wherein the mass ratio of the solid phase coating material to the matrix is 0.02-0.2: 1, and then heating or roasting the ball-milled material to obtain a carbon coating layer, wherein the roasting temperature is 500-1250 ℃.
According to one aspect of the invention, a lithium ion battery anode material comprises the composite material.
The lithium ion battery cathode material provided by the invention comprises the composite material. The composite material effectively relieves the problems of volume expansion of silicon in the processes of embedding and releasing lithium ions and easy oxidation of a nano silicon layer by electrolyte, so that the lithium ion battery cathode material containing the composite material has the advantages of high energy density and stable cycle performance, and effectively relieves the problems of low energy density and poor cycle performance of the conventional silicon-containing lithium ion battery cathode material.
In a preferred embodiment of the present invention, the lithium ion battery negative electrode material comprises a negative electrode material a, a negative electrode material B and a negative electrode material C;
wherein: the negative electrode material A is the composite material;
the negative electrode material B is mainly prepared by mixing the negative electrode material A and auxiliary materials and then drying;
the negative electrode material C comprises a negative electrode material B and a nano carbon layer a, and the nano carbon layer a is coated on the surface of the negative electrode material B.
In a preferred embodiment, the lithium ion battery negative electrode material includes a negative electrode material a, a negative electrode material B, and a negative electrode material C; wherein the negative electrode material A is the composite material; furthermore, the negative electrode material A and the auxiliary material are mixed and dried to prepare the negative electrode material B, and the auxiliary material is added to reduce the internal resistance of the negative electrode material and increase the conductivity of the negative electrode material of the lithium ion battery. Furthermore, the outer layer of the negative electrode material B is coated with a nano carbon layer a to prepare a negative electrode material C, and the nano carbon layer a is used as a protective layer of the negative electrode material B, so that the strength of the negative electrode material can be enhanced, the chance of contact between silicon particles and electrolyte can be reduced or completely prevented, and the stability and the cycle performance of the negative electrode material of the lithium ion battery can be improved.
In a preferred embodiment of the present invention, the average particle size of the negative electrode material B is 2 to 50 μm, preferably 4 to 30 μm.
In a preferred embodiment, the particle size of the negative electrode material B is controlled so that the negative electrode material can be used as it is without a step such as crushing, by matching with a conventional pulping process of the negative electrode material.
Typical but non-limiting preferred embodiments of the above-described average particle size of the matrix material are: 2 μm, 3 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm.
In a preferred embodiment of the invention, in the negative electrode material B, the mass ratio of the negative electrode material a to the auxiliary material is 1: 0.02-0.6, preferably 1: 0.05-0.4;
in a preferred embodiment, the mass ratio of the material a to the auxiliary material in the negative electrode material B can make the material have high capacity and high particle density and strength.
In a preferred embodiment of the present invention, the auxiliary material includes a filler and a binder;
preferably, the filler comprises at least one of microcrystalline graphite, small flake graphite, earthy graphite, expanded graphite, carbon nanotubes, graphene and carbon black;
preferably, the binder comprises at least one of phenolic resin, coal tar, pitch, sucrose, fructose, sodium hydroxymethyl cellulose, starch, polyvinyl chloride, polyvinyl pyrrolidone and polyvinylidene fluoride chloride.
In a preferred embodiment of the present invention, in the negative electrode material C, the thickness of the nano carbon layer a is 1 to 500nm, preferably 2 to 200 nm.
In another preferred embodiment of the present invention, in the negative electrode material C, the thickness of the nano silicon carbide layer is 1 to 500nm, preferably 2 to 200 nm.
Typical but non-limiting preferred embodiments of the thickness of the nano-carbon layer a or nano-silicon carbide layer are: 1nm, 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm and 500 nm.
According to one aspect of the invention, a lithium ion battery comprises the lithium ion battery negative electrode material.
The lithium ion battery provided by the invention comprises the lithium ion battery cathode material. Because the lithium ion battery cathode material has the advantages of high energy density and stable cycle performance, the lithium ion battery containing the lithium ion battery cathode material can obtain the same effect.
According to an aspect of the present invention, an electronic device, a power tool, an electric vehicle, or a power storage system including the lithium ion battery described above.
The lithium ion battery provided by the invention can be widely applied to electronic devices, electric tools, electric vehicles or power storage systems, and because the lithium ion battery has the advantages of high energy density and stable cycle performance, the same effect can be obtained in the electronic devices, the electric tools, the electric vehicles and the power storage systems using the lithium ion battery.
The technical solution of the present invention will be further described with reference to examples and comparative examples.
Example 1
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
taking spherical natural graphite as a substrate, taking trichlorosilane as a silicon source, taking trichlorosilane as a particle with the average particle size of 16-19 mu m, taking mixed gas of trichlorosilane and hydrogen as reaction gas, wherein the volume ratio of trichlorosilane to hydrogen is 1:30, the purity of trichlorosilane is more than 99.95%, and carrying out vapor deposition at 1100 +/-20 ℃ to obtain the substrate coated with a nano silicon layer with the thickness of 70 +/-7 nm; and then, adopting ethylene as a carbon source, adopting a mixed gas of ethylene and nitrogen as a reaction gas, wherein the volume ratio of ethylene to nitrogen is 1:6, the purity of ethylene is more than 99.0%, carrying out vapor deposition on a substrate coated with a nano silicon layer at 900 +/-20 ℃, and obtaining the lithium ion battery cathode material with the outermost layer being a nano carbon layer, the middle layer being a nano silicon layer and the core being a natural graphite layer, wherein the thickness of the deposited carbon layer is 60 +/-6 nm.
Example 2
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
taking mesocarbon microbeads as a substrate, wherein the average grain diameter of the mesocarbon microbeads is 18 +/-2 microns, trichlorosilane is taken as a silicon source, vapor deposition is carried out at 1100 +/-20 ℃, and the reaction gas is mixed gas of trichlorosilane and hydrogen, wherein the volume ratio of trichlorosilane to hydrogen is 1:30, the purity of trichlorosilane is more than 99.95%, so as to obtain the substrate coated with a 60nm +/-6 nm nano silicon layer; adopting propylene as a carbon source, adopting a mixed gas of propylene and nitrogen as a reaction gas, wherein the volume ratio of propylene to nitrogen is 1:5, the purity of propylene is more than 99.0%, carrying out vapor deposition on a substrate coated with a nano silicon layer at 700 +/-20 ℃, the thickness of a deposited carbon layer is 50nm, adopting trichlorosilane as a silicon source, carrying out vapor deposition at 1100 +/-20 ℃, depositing a nano silicon layer with the thickness of 60nm +/-6 nm again, adopting ethylene as a carbon source, adopting a mixed gas of ethylene and nitrogen as a reaction gas, wherein the volume ratio of ethylene to nitrogen is 1:6, the purity of ethylene is more than 99.0%, carrying out vapor deposition at 900 +/-20 ℃, and the thickness of the deposited carbon layer is 100 +/-10 nm, thus obtaining the lithium ion battery cathode material which is respectively carbon-silicon-carbon-silicon-mesocarbon microspheres from outside to inside.
Example 3
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
artificial graphite is used as a matrix, the average particle size of artificial graphite particles is 17 +/-1 mu m, silane is used as a silicon source, propylene is used as a carbon source, vapor deposition is carried out at the temperature of 650 plus or minus 10 ℃, the reaction gas adopts the mixed gas of monosilane, propylene and nitrogen, wherein the volume ratio of the monosilane to the propylene to the nitrogen is 1:0.5:20, the purity of the monosilane is more than 99.5 percent, the purity of the propylene is more than 99.0 percent, a silicon source and a carbon source are simultaneously coated on a substrate to obtain the substrate coated with a nano silicon-carbon mixed coating layer with the thickness of 150nm +/-10 nm, then, taking tetramethylsilane as a carbon source, introducing argon into a tetramethylsilane container placed in an ice-water bath, wherein the purity of the tetramethylsilane is more than 98.0 percent, vapor deposition is carried out at 1100 +/-20 ℃, the thickness of the deposited silicon carbide layer is 20 +/-5 nm, and the lithium ion battery cathode material with the outermost layer being a silicon carbide layer, the middle layer being a carbon-silicon mixed layer and the core being an artificial graphite layer is obtained.
Example 4
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
the carbon black is used as a substrate, the average particle size of the carbon black is 110 +/-10 nm, silane is used as a silicon source, a reaction gas is a mixed gas of silane and argon, the volume ratio of the silane to the argon is 1:40, vapor deposition is carried out at 650 +/-10 ℃, the thickness of a deposited nano silicon layer is about 15nm, propylene is used as a carbon source, the reaction gas is a mixed gas of propylene and argon, the volume ratio of the propylene to the argon is 1:8, the purity of the propylene is more than 99.0%, vapor deposition is carried out at 700 ℃, the thickness of a deposited carbon layer is 40 +/-4 nm, and the lithium ion battery cathode material with a carbon layer as the outermost layer, a nano silicon layer as the middle layer and carbon black as the core is obtained.
Example 5
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
silicon dioxide is used as a substrate, the average grain diameter of silicon dioxide microspheres is 2 +/-0.2 microns, dimethylbenzene is used as a carbon source, reaction gas is mixed gas of dimethylbenzene and nitrogen, wherein the dimethylbenzene is gasified and then mixed with the nitrogen in a volume ratio of 1:8 to serve as the reaction gas, vapor deposition is carried out at the temperature of 750 +/-20 ℃, the carbon deposition thickness is 200 +/-10 nm, monosilane is used as a silicon source, the reaction gas is mixed gas of silane and nitrogen, wherein the volume ratio of the monosilane to the nitrogen is 1:50, the vapor deposition is carried out at the temperature of 650 ℃, the silicon deposition thickness is 70 +/-7 nm, the dimethylbenzene is used as the carbon source, the reaction gas is mixed gas of dimethylbenzene and nitrogen, wherein the dimethylbenzene is gasified and then mixed with the nitrogen in a volume ratio of 1:8 to serve as the reaction gas, the vapor deposition is carried out at the temperature of 750 +/-20 ℃, the carbon deposition thickness is 80 +/-10 nm, and then adding the particles into an HF solution (hydrofluoric acid aqueous solution) with the mass concentration of 5%, mixing and stirring, wherein the mass ratio of the particles to the solution is 1:5, stirring for 2 hours, filtering the solid particles, washing with water with the mass ratio of 10 times, drying at 300 ℃ for 12 hours to obtain the lithium ion battery cathode material with the outer layer being the carbon layer, the inner layer being the nano silicon layer and the inner layer being the carbon layer.
Example 6
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
1. by adopting the negative electrode material obtained in example 4, the auxiliary material adopts phenolic resin as a binder, thermosetting phenolic resin is adopted, the carbon residue rate of the phenolic resin is 62%, the phenolic resin and the negative electrode material are added into 60% ethanol solution together, wherein the phenolic resin: the mass ratio of the negative electrode material is 1:1, the total volume of the phenolic resin and the negative electrode material accounts for 1/2-2/3 of the volume of the ethanol solution, after the mixture is fully stirred and ball-milled, the slurry is dried in a spray drying mode to obtain a negative electrode material B, the outlet temperature of the spray drying is controlled at 105 ℃, the atmosphere is nitrogen, and the particle size D50 of the negative electrode material B is controlled at 10-15 mu m.
2. And curing the negative electrode material B at 120 ℃ for 5h, roasting at 700 +/-20 ℃ in an oxygen-free manner, then adopting ethylene as a carbon source, adopting a mixed gas of ethylene and nitrogen as a reaction gas, wherein the volume ratio of the ethylene to the nitrogen is 1:6, the purity of the ethylene is more than 99.0%, carrying out vapor deposition on a substrate coated with a nano silicon layer at 920 +/-2 ℃, and depositing the carbon layer with the thickness of 150 +/-10 nm to obtain the negative electrode material C of the lithium ion battery.
Example 7
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
1. the negative electrode material prepared in the embodiment 4 is adopted, sticky rice starch and dextrin are adopted as auxiliary materials to serve as binders, the negative electrode material prepared in the embodiment 4 is added into a mixed solution of gelatinized starch and dextrin, wherein the starch: dextrin: the mass ratio of the negative electrode material is 1:3:9, the starch gelatinization temperature is 90 ℃, the gelatinization time is 2 hours, the solid content of the slurry is more than 30%, the slurry is dried in a spray drying mode after being fully stirred and ball-milled to obtain a negative electrode material B, the outlet temperature of the spray drying is controlled at 120 ℃, the atmosphere is air, and the particle size D50 of the negative electrode material B is controlled at 10-15 mu m;
2. and (2) after the negative electrode material B is subjected to anaerobic roasting at 650 +/-20 ℃, adopting propylene as a carbon source, adopting a mixed gas of propylene and nitrogen as a reaction gas, wherein the volume ratio of the propylene to the nitrogen is 1:5, the purity of the propylene is more than 99.0%, and performing vapor deposition on a substrate coated with a nano silicon layer at 750 +/-20 ℃, wherein the thickness of a deposited carbon layer is 100nm to obtain the negative electrode material C of the lithium ion battery.
Example 8
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
1. the negative electrode material obtained in example 4 and asphalt as an auxiliary material were dissolved in quinoline, wherein the softening temperature of the asphalt was 250 ℃, and the ratio of asphalt: the mass ratio of the negative electrode material is 1:2, the slurry is dried in vacuum for 8 hours at 70 ℃ after being fully stirred and ball-milled, then the slurry is crushed into particles with the particle size of less than 5mm, the particles are kept for 5 hours at 700 ℃ in nitrogen atmosphere, and the particles are crushed and ball-milled to obtain a negative electrode material B with D50 of 12 mu m after being cooled;
2. and (3) after the negative electrode material B is subjected to anaerobic roasting at 900 +/-20 ℃, introducing argon into a hexamethyldisilane container placed in a water bath at 50 ℃ by taking hexamethyldisilane as a carbon source, wherein the purity of the hexamethyldisilane is more than 98.0%, performing vapor deposition at 1100 +/-20 ℃, and obtaining the negative electrode material of the lithium ion battery, wherein the thickness of a deposited silicon carbide layer is 50 +/-5 nm.
Example 9
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
1. adopting the negative electrode material obtained in the embodiment 5, and adopting microcrystalline graphite and polyvinylpyrrolidone as auxiliary materials, wherein the grain size of the microcrystalline graphite is less than 2 μm, the purity is more than 99%, and the average molecular weight of the polyvinylpyrrolidone is 58000, proportioning the negative electrode material, the microcrystalline graphite and the polyvinylpyrrolidone according to the mass ratio of 5:4:0.4, firstly dissolving the polyvinylpyrrolidone in water, then adding the negative electrode material and the microcrystalline graphite into the solution, fully stirring and ball-milling, drying the slurry in a spray drying manner to obtain a negative electrode material B, controlling the outlet temperature of the spray drying at 120 ℃, controlling the atmosphere at air, and controlling the grain size D50 of the negative electrode material B at 15-20 μm.
2. And then, adopting ethylene as a carbon source, adopting a mixed gas of ethylene and nitrogen as a reaction gas, wherein the volume ratio of the ethylene to the nitrogen is 1:6, the purity of the ethylene is more than 99.0%, carrying out vapor deposition on the substrate coated with the nano silicon layer at 920 +/-2 ℃, and obtaining the lithium ion battery cathode material, wherein the thickness of the deposited carbon layer is 100 +/-10 nm.
Example 10
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
1. the negative electrode material obtained in example 5 is adopted, and the auxiliary material is carbon black and thermosetting phenolic resin, wherein the particle size of the carbon black is 110 +/-10 nm, the carbon residue rate of the phenolic resin is 62%, and the negative electrode material: carbon black: adding 60% ethanol solution into phenolic resin according to the mass ratio of 3:1:1, wherein the total volume of the negative electrode material, the carbon black and the phenolic resin accounts for 1/2-2/3 of the volume of the ethanol solution, fully stirring and ball milling, drying the slurry in a spray drying mode to obtain a negative electrode material B, controlling the outlet temperature of the spray drying at 105 ℃, controlling the atmosphere to be nitrogen, and controlling the particle size D50 of the negative electrode material B at 8-15 mu m.
2. And curing the negative electrode material B at 120 ℃, carrying out anaerobic roasting at 700 +/-20 ℃, introducing nitrogen into a monochlorosilane container placed in a water bath at 10 ℃ by taking monochlorosilane as a carbon source, wherein the purity of the monochlorosilane is more than 99.0%, carrying out vapor deposition at 1050 +/-20 ℃, and obtaining the negative electrode material of the lithium ion battery, wherein the thickness of a deposited silicon carbide layer is 100 +/-10 nm.
Example 11
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
taking spherical natural graphite as a substrate, taking the average particle size of particles as 16-19 mu m, taking trichlorosilane as a silicon source, taking mixed gas of trichlorosilane and hydrogen as reaction gas, wherein the volume ratio of trichlorosilane to hydrogen is 1:30, the purity of trichlorosilane is more than 99.95%, and carrying out vapor deposition at 1100 +/-20 ℃ to obtain the substrate coated with a nano silicon layer with the thickness of 300 +/-6 nm; and then, adopting ethylene as a carbon source, adopting a mixed gas of ethylene and nitrogen as a reaction gas, wherein the volume ratio of ethylene to nitrogen is 1:6, the purity of ethylene is more than 99.0%, carrying out vapor deposition on a substrate coated with a nano silicon layer at 900 +/-20 ℃, and obtaining the lithium ion battery cathode material with the outermost layer being a nano carbon layer, the middle layer being a nano silicon layer and the core being a natural graphite layer, wherein the thickness of the deposited carbon layer is 60 +/-6 nm.
Example 12
A preparation method of a lithium ion battery negative electrode material comprises the following steps:
the negative electrode material obtained in example 5 is adopted, and the auxiliary material is carbon black and thermosetting phenolic resin, wherein the particle size of the carbon black is 110 +/-10 nm, the carbon residue rate of the phenolic resin is 62%, and the negative electrode material: carbon black: adding 60% ethanol solution into phenolic resin according to the mass ratio of 3:1:1, wherein the total volume of the negative electrode material, the carbon black and the phenolic resin accounts for 1/2-2/3 of the volume of the ethanol solution, fully stirring and ball milling, drying the slurry in a spray drying mode to obtain a negative electrode material B, controlling the outlet temperature of the spray drying at 105 ℃, controlling the atmosphere to be nitrogen, and controlling the particle size D50 of the negative electrode material B at 8-15 mu m.
Comparative example 1
The lithium ion battery cathode adopts BTR-918 natural graphite of New Bistri Material group GmbH.
Comparative example 2
Grinding silicon powder with the average particle size of 10 microns in an alcohol medium by using a sand mill, wherein the sand mill adopts mixed zirconium beads with the particle sizes of 50 microns, 100 microns and 200 microns, the average particle size of the ground silicon powder is controlled to be 120 plus 150nm, filtering wet nano silicon powder mixed with alcohol, performing vacuum drying at 50 ℃ to obtain dried nano silicon powder, adding the dried nano silicon powder, microcrystalline graphite and phenolic resin into a 60% ethanol solution, adopting thermosetting phenolic resin, ensuring that the carbon residue rate of the phenolic resin is 62%, the particle size of the microcrystalline graphite is less than 2 microns, and the purity is more than 99%, wherein the nano silicon powder: microcrystalline graphite: the mass ratio of the phenolic resin is 1:1:1, the slurry is dried in a spray drying mode after being fully stirred and ball-milled to obtain a negative electrode material, the outlet temperature of the spray drying is controlled at 105 ℃, the atmosphere is nitrogen, the particle size D50 of the negative electrode material is controlled at 10-15 mu m, the spray-dried particles are solidified for 5 hours at 120 ℃, and the negative electrode material containing nano silicon is obtained after anaerobic roasting at 700 +/-20 ℃.
Experimental example 1
In order to show that the lithium ion battery cathode material has the advantages of high energy density and stable cycle performance, the lithium ion battery cathode material prepared in the embodiments 1-12 and the comparative examples 1 and 2 is further prepared into a lithium ion battery for detection, and the specific method comprises the following steps:
1. the lithium sheet material is the negative electrode material by mass: SP: CMC: SBR 88: 5: 3: 4, mixing the materials, coating the single surface of the copper foil with the coating thickness of 200 mu m, drying, rolling, and then preparing the round pole piece with the diameter of 14mm by using a sheet punching machine.
2. A2032 type button half cell is assembled by a lithium sheet as a counter electrode and a Celgard2325 diaphragm with the thickness of 25 mu m and a pole piece, and an electrolyte system adopts 1MLiPF 6/EC: DMC: EMC 1:1: 1. The performance of the material is measured by adopting a blue battery testing system of blue-electricity electronic products of Wuhan City, and adopting constant current charging and discharging, wherein the voltage platform is 0.005-1.5V.
The specific performance detection results are as follows:
from the table, in comparative example 1 (commercial material), the reversible capacity of the anode material prepared by the method of the present invention in the first circle is greatly improved, from 364.8mAh/g (comparative example 1) to 440-1300 mAh/g, especially in examples 1, 2, 3, 6, 7, 8, 9, 10, the capacity is improved to 440-900mAh/g, the first circle efficiency is maintained at about 90%, and the first circle capacity of more than 94% can be maintained after 100 circles, so that the method has a good commercial application prospect, wherein the comprehensive effect of example 9 is the best.
Further, in order to more intuitively express the technical effects of the negative electrode material of the lithium ion battery prepared by the present application, the evaluation data of the first 100 circles of the batteries prepared in examples 1, 4, 6 and 10 and the evaluation data of the batteries prepared in examples 11 and 12, comparative examples 1 and 2 are adopted, and the specific results are shown in fig. 1, fig. 2 and fig. 3.
As can be seen from fig. 1, 2 and 3, although the first cycle capacity of example 11 is not high, the stability of example 1 is much higher than that of example 11, and example 11 can still maintain relatively stable charge and discharge in the first ten or more cycles, but after that, the data suddenly drop, which indicates that the silicon deposition layer which is too thick gradually breaks and atomizes and fails in the process of multiple charge and discharge, resulting in a sharp drop of performance; compared with the embodiment 4, the embodiment 6 has the advantages that the capacity is reduced to some extent due to the addition of the compounding and coating links, the first-turn coulombic efficiency is benefited, the capacity retention rate reaches 99.5% after the circulation of 100 turns, and the first-turn coulombic efficiency and the 100-turn circulation retention rate are equivalent to those of the commercial graphite cathode in the comparative example 1; compared with the embodiment 12, the embodiment 10 has the advantages that the capacity is slightly reduced due to the addition of the coating layer, but the coating layer greatly enhances the stability of the material in the charging and discharging process and greatly improves the coulombic efficiency of the first circle, and the capacity reduction range is obviously smaller than that of the embodiment 12 along with the charging and discharging; in contrast, in comparative example 2, nano-silicon is obtained in a conventional physical manner and is molded, and the obtained negative electrode material has a high initial capacity, but the capacity is reduced very quickly, and finally, the capacity retention rate is only 13% after 100 cycles of charge and discharge.
The data in the table and shown in figure 1, the negative electrode material obtained by the method provided by the invention has greatly improved capacity compared with the commercial graphite negative electrode material, because the nano-scale silicon deposition coating with proper thickness is adopted, and the carbon deposition coating is carried out outside the silicon, the specific capacity and the stability of the negative electrode material can be effectively improved, furthermore, the smaller material is adopted, the particles coated by the silicon and the carbon are compounded with other materials to prepare particles and then are subjected to coating treatment, furthermore, the particles coated by the silicon and the carbon are treated to remove the core layer to form the hollow material, the hollow material is compounded with other materials to prepare particles and then is subjected to coating treatment, so that the silicon content in the material is effectively improved, the thinner silicon layer can be ensured to be coated, and the volume effect brought by the silicon charging and discharging process is reduced to the lowest level, the negative electrode material with high capacity, high first-turn efficiency and stable circulation is obtained.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (17)
1. The lithium ion battery cathode material is characterized by comprising a cathode material A, a cathode material B and a cathode material C;
wherein: the negative electrode material A is a composite material; the composite material sequentially comprises from inside to outside: a solid core, a nano silicon layer and a nano carbon layer;
providing a solid core, and then coating at least one layer of nano silicon layer and at least one layer of nano carbon layer on the surface of the solid core to obtain a composite material; the adjacent two layers of the nano silicon layer and the nano carbon layer in the composite material are different, and the nano carbon layer is arranged on the outermost layer of the composite material;
the solid core mainly comprises a base material, and the average particle size of the base material is 0.03-3 mu m;
the matrix material comprises any one of natural graphite, artificial graphite, expanded graphite, hard carbon, soft carbon, mesocarbon microbeads, petroleum coke, carbon fibers, pyrolytic resin carbon, carbon black, carbon nanotubes, graphene, tin oxide, tin composite oxide, silicon monoxide, titanium dioxide, silicon dioxide, calcium oxide, calcium carbonate, aluminum oxide, magnesium oxide or magnesium carbonate;
the thickness of the nano carbon layer is 1-100 nm;
the negative electrode material B is mainly prepared by mixing the negative electrode material A and auxiliary materials and then drying;
the negative electrode material C comprises a negative electrode material B and a nano carbon layer a, and the nano carbon layer a is coated on the surface of the negative electrode material B.
2. The negative electrode material for a lithium ion battery according to claim 1, wherein the average particle size of the matrix material is 0.05 to 1 μm.
3. The negative electrode material for the lithium ion battery according to claim 1, wherein the nano carbon layer has a thickness of 2 to 50 nm.
4. The lithium ion battery anode material according to claim 1, wherein the lithium ion battery anode material comprises an anode material A, an anode material B and an anode material C;
the composite material sequentially comprises from inside to outside: a solid core, a nano silicon layer and a nano carbon layer;
providing a solid core, and then coating at least one layer of nano silicon layer and at least one layer of nano carbon layer on the surface of the solid core to obtain a composite material; the adjacent two layers of the nano silicon layer and the nano carbon layer in the composite material are different, and the nano carbon layer is arranged on the outermost layer of the composite material;
the solid core mainly comprises a base material, and the average particle size of the base material is 0.05-1 mu m;
the matrix material comprises any one of natural graphite, artificial graphite, expanded graphite, hard carbon, soft carbon, mesocarbon microbeads, petroleum coke, carbon fibers, pyrolytic resin carbon, carbon black, carbon nanotubes, graphene, tin oxide, tin composite oxide, silicon monoxide, titanium dioxide, silicon dioxide, calcium oxide, calcium carbonate, aluminum oxide, magnesium oxide or magnesium carbonate;
the thickness of the nano carbon layer is 2-50 nm;
the negative electrode material B is mainly prepared by mixing the negative electrode material A and auxiliary materials and then drying;
the negative electrode material C comprises a negative electrode material B and a nano silicon carbide layer, and the surface of the negative electrode material B is coated with the nano silicon carbide layer.
5. The lithium ion battery anode material according to claim 1, wherein the lithium ion battery anode material comprises an anode material A, an anode material B and an anode material C;
the composite material sequentially comprises from inside to outside: the hollow core, the first nano carbon layer, the first nano silicon layer and the second nano carbon layer;
the step of removing the solid core to prepare the hollow core comprises the following steps: dissolving a matrix material by using an acid solution, and then calcining to prepare a hollow composite material not containing the matrix material;
the specific method comprises the following steps: uniformly mixing the composite material with an acid solution or an alkali solution, then carrying out solid-liquid separation, removing the residual solution through washing and filtering, and finally obtaining the liquid-free composite material with the hollow core in a drying or roasting mode;
the acid solution used for removing the solid core and preparing the hollow core is one or a mixture of more than two of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, formic acid and acetic acid;
the matrix material comprises any one of tin oxide, tin composite oxide, silicon monoxide, titanium dioxide, silicon dioxide, calcium oxide, calcium carbonate, aluminum oxide, magnesium oxide or magnesium carbonate;
the thickness of the nano carbon layer is 1-100 nm;
the negative electrode material B is mainly prepared by mixing the negative electrode material A and auxiliary materials and then drying;
the negative electrode material C comprises a negative electrode material B and a nano carbon layer a, and the nano carbon layer a is coated on the surface of the negative electrode material B.
6. The negative electrode material of the lithium ion battery as claimed in claim 5, wherein the alkali solution used for removing the solid core to prepare the hollow core is one or a mixture of more than two of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia water, sodium amide and sodium methoxide.
7. The lithium ion battery negative electrode material of any one of claims 1 to 6, wherein in the negative electrode material B, the mass ratio of the negative electrode material A to the auxiliary material is 1: 0.02-0.6.
8. The lithium ion battery negative electrode material of claim 7, wherein in the negative electrode material B, the mass ratio of the negative electrode material A to the auxiliary material is 1: 0.05-0.4.
9. The lithium ion battery negative electrode material of claim 7, wherein the auxiliary material comprises a filler and a binder.
10. The negative electrode material for a lithium ion battery of claim 9, wherein the filler comprises at least one of microcrystalline graphite, small flake graphite, expanded graphite, carbon nanotubes, graphene, and carbon black.
11. The lithium ion battery anode material of claim 9, wherein the binder comprises at least one of phenolic resin, coal tar, pitch, sucrose, fructose, sodium hydroxymethyl cellulose, starch, polyvinyl chloride, polyvinyl pyrrolidone, and polyvinylidene fluoride chloride.
12. The negative electrode material for lithium ion batteries according to any one of claims 1 to 6, wherein the thickness of the nanocarbon layer a in the negative electrode material C is 2 to 200 nm.
13. The negative electrode material for the lithium ion battery according to any one of claims 1 to 6, wherein the thickness of the nano silicon carbide layer in the negative electrode material C is 2 to 200 nm.
14. The negative electrode material C of any of claims 1-6, wherein the nano-silicon layer is coated by vapor deposition.
15. The negative electrode material C as claimed in any one of claims 1 to 6, wherein the nano carbon layer is coated by any one of vapor deposition, liquid phase coating and solid phase coating.
16. A lithium ion battery, characterized in that the lithium ion battery comprises the lithium ion battery negative electrode material of any one of claims 12 to 15.
17. An electronic device, a power tool, an electric vehicle, or a power storage system comprising the lithium ion battery of claim 16.
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| CN113582182A (en) * | 2021-07-14 | 2021-11-02 | 珠海冠宇电池股份有限公司 | Silicon-carbon composite material and preparation method and application thereof |
| CN114335533A (en) * | 2021-12-16 | 2022-04-12 | 珠海冠宇电池股份有限公司 | Negative electrode material and battery comprising same |
| CN114361420A (en) * | 2022-01-10 | 2022-04-15 | 四川轻化工大学 | Spiral nano carbon fiber composite material, preparation method thereof and lithium battery |
| CN114512654A (en) * | 2022-02-25 | 2022-05-17 | 松山湖材料实验室 | Nano-silicon composite powder coated with textured carbon, and preparation method and application thereof |
| CN114824199A (en) * | 2022-03-29 | 2022-07-29 | 广东氢发新材料科技有限公司 | Silicon carbide-silicon-graphite composite material and preparation method and application thereof |
| CN114843460A (en) * | 2022-04-14 | 2022-08-02 | 中创新航科技股份有限公司 | Composite material, preparation method and electrochemical device |
| CN114906835B (en) * | 2022-05-24 | 2023-03-21 | 四川新能源汽车创新中心有限公司 | Carbon material, preparation method thereof and lithium metal battery |
| CN115448287B (en) * | 2022-10-13 | 2023-11-28 | 西华大学 | Lithium ion battery negative electrode material and preparation method thereof |
| CN115966681B (en) * | 2023-03-16 | 2023-10-27 | 江苏正力新能电池技术有限公司 | Battery self-supporting anode and preparation method and application thereof |
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