CN113839014B - Silicon-carbon negative electrode material, preparation method and application thereof, and lithium ion battery - Google Patents

Silicon-carbon negative electrode material, preparation method and application thereof, and lithium ion battery Download PDF

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CN113839014B
CN113839014B CN202010513230.3A CN202010513230A CN113839014B CN 113839014 B CN113839014 B CN 113839014B CN 202010513230 A CN202010513230 A CN 202010513230A CN 113839014 B CN113839014 B CN 113839014B
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silicon
carbon
negative electrode
source
electrode material
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CN113839014A (en
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孙赛
张丝雨
高焕新
张同宝
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • 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
    • 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
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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 relates to the field of lithium ion batteries, and discloses a silicon-carbon negative electrode material, a preparation method and application thereof, and a lithium ion battery. The preparation method of the silicon-carbon anode material comprises the following steps: (1) Mixing a carbon-containing substance with a chain polymer solution, adding a silicon source into the mixture, and separating the obtained mixture to obtain a solid substance; (2) The solid material is blended with a carbon source precursor and then calcined. The silicon-carbon anode material provided by the invention can improve the dispersibility of nano silicon, relieve the volume expansion of silicon, improve the cycling stability of the material, and can improve the energy density of a lithium battery when applied to the lithium ion battery.

Description

Silicon-carbon negative electrode material, preparation method and application thereof, and lithium ion battery
Technical Field
The invention relates to the field of lithium ion batteries, in particular to a silicon-carbon negative electrode material, a preparation method and application thereof, and a lithium ion battery.
Background
Graphite is widely adopted in lithium ion batteries at presentThe theoretical lithium storage capacity of the graphite anode material is 372mAh/g, so that the requirements of a new product on high power or large capacity of the lithium ion battery can not be met, and the further development of the capacity of the lithium ion battery is seriously hindered. The theoretical specific capacity of the silicon-based anode material is 4200mA.h.g -1 The cathode material with the highest gram capacity at present is a cathode material, but because large volume change can occur in the subsequent lithium intercalation and deintercalation process, pulverization and secondary agglomeration of the material are caused to slowly deactivate active substances, so that the capacity of the material is fast attenuated, and in addition, the volume change in the lithium intercalation and deintercalation process can also cause tight electrical contact between a cathode sheet and a current collector to be lost. Therefore, whether the cycle performance is improved becomes a key technology for whether the silicon-based anode material can be applied in a large-scale commercialization way, and once the silicon-based anode material is successfully applied, the energy density of the lithium battery can be remarkably improved, so that the once-charging endurance of 1000 km becomes possible.
In order to solve the problems, scientific researchers adopt methods of carbon coating, reserving buffer space and the like to improve the comprehensive electrical property of the silicon-based material. The Chinese patent application with publication number of CN102496701A reports a coated silicon-carbon negative electrode material for lithium ion batteries, which is characterized in that silicon powder particles are coated by carbon nano tubes and amorphous carbon, so that the conductivity and ionic conductivity of the material are improved, and the cycle performance is obviously improved, but in the charging and discharging process, as nano silicon powder forms micron-sized secondary particles before coating, the carbon nano tubes and amorphous carbon serving as coating layers can not play a role in well inhibiting the volume expansion of a matrix, so that after multiple cycles, the material can be pulverized faster, and the capacity of the material is attenuated rapidly. The Chinese patent application with publication number of CN103490045A reports a composite system prepared by a CVD method and coated with an amorphous carbon layer outside silicon particles, improves the structure and the conductivity of a silicon material, and can inhibit the volume effect in the process of lithium intercalation and deintercalation to a certain extent, thereby improving the cycle performance of the material. However, the CVD method is difficult to control and has many uncertainty factors, so that mass production is difficult to achieve. The Chinese patent application CN102332571A discloses a silicon-carbon composite anode active material and a manufacturing method, wherein a carbon layer is deposited on the surface of silicon in advance, then the silicon layer is mixed with an organic polymer, and the mixture is carbonized after spray granulation, so that a composite structure with a core implanted with silicon is obtained. However, in the structure, the surface of the silicon is firstly etched, then carbon is deposited, and the process is complex; and the spraying process is complex and the equipment is expensive.
Therefore, the method solves the problem of dispersity of nano silicon particles in the silicon-carbon negative electrode material, reduces agglomeration of the nano silicon particles, effectively inhibits the volume effect of silicon, improves the cycle performance and specific capacity of the silicon-carbon composite negative electrode material, and is one of the problems to be solved in the field of preparing high-capacity silicon-based negative electrode materials.
Disclosure of Invention
The invention aims to solve the problems of serious agglomeration and serious volume expansion of a silicon-based anode material in the prior art, and provides a silicon-carbon anode material, a preparation method and application thereof and a lithium ion battery. The silicon-carbon anode material provided by the invention can improve the dispersibility of nano silicon, relieve the volume expansion of silicon, improve the cycling stability of the material, and can improve the energy density of a lithium battery when applied to the lithium ion battery.
In order to achieve the above object, a first aspect of the present invention provides a silicon-carbon anode material, which includes a carbonaceous material, and a silicon-containing material layer and an amorphous carbon layer sequentially coated on an outer surface of the carbonaceous material.
Preferably, the silicon-containing material layer further contains a phosphorus element, and further preferably, in the silicon-carbon anode material, the mass ratio of the phosphorus element to the silicon-containing material is 0.01-0.28:1.
The second aspect of the invention provides a preparation method of a silicon-carbon anode material, which comprises the following steps:
(1) Mixing a carbon-containing substance with a chain polymer solution, adding a silicon source into the mixture, and separating the obtained mixture to obtain a solid substance;
(2) The solid material is blended with a carbon source precursor and then calcined.
The third aspect of the invention provides the silicon-carbon anode material prepared by the preparation method.
The fourth aspect of the invention provides an application of the silicon-carbon anode material in a lithium ion battery.
The fifth aspect of the invention provides a lithium ion battery, which comprises the silicon-carbon negative electrode material, the positive electrode material containing lithium element, a diaphragm and electrolyte.
The silicon-carbon anode material provided by the invention has a carbon-silicon-carbon structure, and an inner carbon core (carbon-containing substance) provides a buffer space to relieve the volume expansion of silicon in the charging and discharging processes. The silicon-containing material layer plays a role in improving capacity in the whole system, and the amorphous carbon layer can cover all silicon-containing materials, so that side reactions of active materials and electrolyte are avoided, and the volume effect of silicon in a high lithium removal state can be inhibited. Preferably, phosphorus is introduced into the silicon-containing material layer, so that the possibility of agglomeration of silicon in the preparation and charge-discharge processes can be remarkably reduced, and the electrical property deterioration caused by agglomeration of silicon powder is improved.
The silicon-carbon negative electrode material provided by the invention greatly improves the reversible capacity and the cycling stability of the negative electrode material in the use process, and can obviously improve the energy density of a lithium battery. From example 1, it can be seen that the silicon-carbon anode material (reversible capacity 517 mAh.g) -1 ) Under the constant-current discharge multiplying power of 0.5C, the capacity retention rate can reach more than 80% after 600 times of circulation.
Drawings
FIG. 1 is an SEM photograph of crystalline flake graphite used in example 1;
FIG. 2 is an SEM photograph of a coated silicon-containing material layer of example 1;
FIG. 3 is an SEM photograph of a silicon-carbon anode material obtained in example 1;
FIG. 4 is a cycle stability test curve of the silicon carbon anode material obtained in example 1;
FIG. 5 is a cycle stability test curve of the negative electrode material of the lithium battery of comparative example 1;
FIG. 6 is a cycle stability test curve of the anode material of the lithium battery in example 11;
fig. 7 is a cycle stability test curve of the negative electrode material of the lithium battery in comparative example 2.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
In the present invention, the median particle diameter refers to a particle diameter corresponding to a cumulative particle size distribution percentage of 50%, and is commonly used to represent the average particle size of powder. In the invention, the median particle diameter of the silicon carbon anode material can be obtained by dynamic light scattering characterization without special description.
The invention provides a silicon-carbon anode material, which comprises a carbonaceous substance, and a silicon-containing material layer and an amorphous carbon layer which are sequentially coated on the outer surface of the carbonaceous substance.
In the invention, the sequential coating means that the outer surface of the carbonaceous material is coated with a silicon-containing material layer, and the outer surface of the silicon-containing material layer is coated with an amorphous carbon layer. The coating refers to an assembled structure formed by uniformly coating one material with the other material through chemical bonds or other acting forces.
According to the invention, the silicon-containing material layer contains silicon-containing materials. The present invention has a wide range of choices for the form of presence of the silicon-containing material, and may be, for example, particles and/or films.
According to the present invention, preferably, the silicon-containing material is selected from at least one of elemental silicon, siOx, and silicon-containing alloy, wherein 0.6< x <1.5. The adoption of the preferred embodiment is more beneficial to further improving the reversible capacity of the silicon-carbon anode material. The silicon-containing material can be obtained commercially or prepared by the existing method.
Preferably, the silicon-containing alloy is selected from at least one of a silicon-aluminum alloy, a silicon-magnesium alloy, a silicon-zirconium alloy, and a silicon-boron alloy. The silicon content of the silicon-containing alloy according to the invention is selected within a wide range, for example, from 10 to 50% by weight, based on the total amount of the silicon-containing alloy. The method for producing the silicon-containing alloy is not particularly limited, and a specific method for producing the silicon-containing alloy is now provided, and the invention is not limited thereto. The preparation method of the silicon-containing alloy preferably comprises the following steps: 1) Ball milling aluminum powder and silicon powder for 30min under the protection of inert atmosphere; 2) The mixture was treated at 900℃for 10h.
According to the present invention, preferably, the silicon-containing material is elemental silicon and/or a silicon-aluminum alloy.
Preferably, the silicon-containing material has a median particle diameter of 0.1 to 5 μm, and more preferably, the silicon-containing material has a median particle diameter of 0.1 to 0.5 μm.
According to a preferred embodiment of the present invention, the silicon-containing material layer further contains a phosphorus element. The content selection range of the phosphorus element is wider, the phosphorus element can be properly selected according to the amount of the silicon-containing material, and preferably, in the silicon-carbon anode material, the mass ratio of the phosphorus element to the silicon-containing material is 0.01-0.28:1, more preferably 0.07 to 0.15:1. by adopting the preferred embodiment, the modification of phosphorus element to the silicon-containing material is facilitated, the possibility of agglomeration of silicon in the preparation and charging and discharging processes is remarkably reduced, and the electrical property deterioration caused by agglomeration of silicon powder is further improved.
According to a preferred embodiment of the invention, the mass ratio of the carbonaceous material, the amorphous carbon layer and the silicon-containing material is 1-20:0.8-2:1, further preferably 2 to 10:1-1.3:1. with the adoption of the preferred embodiment, the reversible capacity and the cycling stability of the anode material are improved, and the energy density of the lithium battery can be further improved.
According to the present invention, it is preferable that the silicon carbon negative electrode material has a median particle diameter of 1 to 50 μm, for example, 1 μm, 5 μm, 10 μm, 15 μm, 25 μm, 50 μm, and any value in a range constituted by any two of these values. Still more preferably, the silicon carbon negative electrode material has a median particle diameter of 5 to 25 μm.
According to the present invention, preferably, the carbonaceous material is selected from at least one of natural graphite, artificial graphite, and needle coke. The carbonaceous material may be obtained commercially or by self-preparation, and the present invention is not particularly limited thereto. The natural graphite is not particularly limited, and may be, for example, flake graphite.
Preferably, the carbonaceous material is crystalline flake graphite and/or needle coke.
The amorphous carbon layer is not particularly limited in the present invention, and for example, the amorphous carbon layer may be obtained by firing a carbon source precursor. Preferably, the carbon source precursor is selected from at least one of pitch, polyacrylonitrile, phenolic resin, epoxy resin, polyfurfuryl alcohol, glucose and cellulose, preferably at least one of pitch, polyacrylonitrile and phenolic resin. The adoption of the preferred embodiment is more beneficial to the complete coating of the amorphous carbon layer and is more beneficial to the further improvement of the electrochemical performance of the prepared anode material.
The asphalt of the present invention includes petroleum asphalt, coal tar asphalt, natural asphalt and modified asphalt, and has a meaning conventionally understood by those skilled in the art, and is commercially available.
The second aspect of the invention provides a preparation method of a silicon-carbon anode material, which comprises the following steps:
(1) Mixing a carbon-containing substance with a chain polymer solution, adding a silicon source into the mixture, and separating the obtained mixture to obtain a solid substance;
(2) The solid material is blended with a carbon source precursor and then calcined.
According to the preparation method provided by the invention, the carbon-containing substance is selected as described above, and is not described herein.
According to the present invention, the silicon source may be the above silicon-containing material or may be a silicon-containing substance that can be converted into the above silicon-containing material by the firing in the step (2), preferably, the silicon source is the above silicon-containing material, and the specific kind and median particle size of the silicon source are selected as described above, which is not described herein.
According to the present invention, preferably, the chain polymer contains at least one of a hydroxyl group, an ester group, and an amide group. For example, the chain polymer is preferably a substance containing a repeating unit of carboxyl group, hydroxyl group, ester group or amide group.
Preferably, the chain polymer is at least one selected from polyacrylic acid, polyacrylate, sodium alginate, polyurethane and sodium carboxymethyl cellulose, and more preferably polyacrylic acid. With the adoption of the preferred embodiment, the carboxyl in the polyacrylic acid can form hydrogen bonds with hydroxyl groups on the surface of the silicon-containing material, so that the coating of the silicon-containing material is facilitated.
The molecular weight of the chain polymer of the present invention is selected in a wide range, and the weight average molecular weight of the chain polymer is preferably 2000 to 5000000, more preferably 80000 to 300000.
According to the present invention, the chain polymer is preferably used in an amount of 0.1 to 1 part by weight, more preferably 0.1 to 0.5 part by weight, relative to 1 part by weight of the carbonaceous matter.
The concentration of the chain polymer solution according to the present invention is selected in a wide range, preferably 3 to 20% by weight, more preferably 3 to 8% by weight.
The solvent in the chain polymer solution is selected from a wide range as long as the solvent can form a solution with the chain polymer, and preferably the solvent in the chain polymer solution is at least one of water, ethanol, acetone, N' N-dimethylformamide and N-methylpyrrolidone.
The specific embodiment of mixing the carbonaceous material with the chain polymer solution in the step (1) is not particularly limited, and the mixing is preferably performed under stirring conditions, and the stirring time and the stirring speed are not particularly limited, so as to enable the solid to be uniformly dispersed, and the specific operation is well known to those skilled in the art and will not be repeated herein.
In the present invention, the silicon source may be introduced directly in step (1), or may be introduced in the form of a solution, and preferably, the silicon source is introduced in the form of a solution.
According to the method provided by the invention, preferably, the solution also contains a phosphorus source. I.e. mixing a silicon source and a phosphorus source in the presence of a solvent to obtain a solution, and introducing the solution. By adopting the preferred embodiment, the modification of phosphorus element to the silicon source is facilitated, the possibility of agglomeration of silicon in the preparation and charging and discharging processes is remarkably reduced, and the electrical property deterioration caused by agglomeration of silicon powder is further improved.
According to the invention, preferably, the phosphorus source is a polyphosphoric acid, preferably phytic acid; wherein said phytic acid is a commonly understood meaning by a person skilled in the art and is commercially available.
According to the present invention, it is preferable that the mass ratio of the phosphorus source to the silicon source in terms of phosphorus element is 0.01 to 0.28:1, preferably 0.07 to 0.15:1.
according to a preferred embodiment of the present invention, the step (1) includes:
(1-1) mixing a silicon source and a phosphorus source in the presence of a solvent to obtain a solution A;
(1-2) mixing a carbonaceous material with a solution of a chain polymer, then adding the solution A thereto, and separating the resulting mixture to obtain a solid material.
According to one embodiment of the present invention, the solvent in step (1-1) is preferably at least one of water, ethanol, acetone, N' N-dimethylformamide and N-methylpyrrolidone.
According to one embodiment of the present invention, step (1-1) comprises: the phosphorus source is mixed with a solvent to obtain a phosphorus source solution (concentration may be 10-45 wt%) and then the silicon source is added for the mixing. The conditions for the mixing are not particularly limited, and for example, the mixing may be performed under stirring for a period of 1 to 8 hours.
According to one embodiment of the invention, in step (1-2), after the addition of the solution A, stirring is continued (preferably for 1-6 h), and then the separation is carried out.
The separation is not particularly limited as long as the solid and the liquid are separated, and filtration, such as suction filtration, is preferable.
According to the method provided by the invention, the carbon source precursor may be selected as described above, and will not be described herein.
According to the present invention, preferably, the mass ratio of the carbonaceous matter, the carbon source precursor in terms of carbon element, to the silicon source is 1 to 20:0.8-2:1, further preferably 2 to 10:1-1.3:1. with the adoption of the preferred embodiment, the reversible capacity and the cycling stability of the anode material are improved, and the energy density of the lithium battery can be further improved.
The addition amount of the carbon source precursor may be selected by those skilled in the art according to the above ratio by the amount of carbon in the carbon source precursor. In the embodiment of the invention, the carbon source precursor is taken as asphalt for illustration, the residual carbon content of the asphalt is 0.2-0.8 wt%, and the mass ratio of the carbon source precursor to the silicon source is 1-10:1, further preferably 1.25 to 6.5:1.
according to the present invention, preferably, the blending of step (2) comprises at least one of ball milling, spray drying and shear dispersing. By adopting the preferred embodiment, the carbon source precursor is more favorable for uniformly coating the silicon surface.
The specific operations of the ball milling, spray drying and shearing dispersion are not particularly limited in the present invention, and may be selected according to the median particle diameter of the target product. Preferably, specific conditions of the ball milling, spray drying and shearing dispersion are such that the median particle diameter of the prepared silicon carbon negative electrode material is 1 to 50 μm, and more preferably 5 to 25 μm.
According to the present invention, the solvent used for the solid ball milling, spray drying, shearing dispersion may be a solvent conventionally used in the art, preferably at least one of ethanol, acetone, tetrahydrofuran, N-dimethylformamide and N-methylpyrrolidone.
The amount of solvent added according to the invention is chosen within a wide range, for example a slurry having a solids content of 10 to 35% by weight is obtained by mixing.
According to one embodiment of the invention, the method further comprises, after said mixing in step (2), separating the mixed material and subjecting the separated solids to said calcination. The separation may be a conventional separation method in the art, such as centrifugation, filtration separation. Preferably, the method further comprises drying the solid, followed by said calcining. The drying conditions of the invention are selected in a wide range, preferably at a temperature of 80-150 ℃ for a time of 1-10 hours.
According to the present invention, preferably, the conditions of the firing include: under inert atmosphere, the temperature is 600-1000 ℃, preferably 700-900 ℃; the time is 10-240min, preferably 20-60min. The inert atmosphere may be provided by at least one of nitrogen, helium, argon, and krypton, and the embodiment of the present invention is exemplified by nitrogen, but the present invention is not limited thereto.
The temperature rise rate of the firing is not particularly limited, and may be, for example, 1 to 10℃per minute. The embodiment of the invention is exemplified by 5 ℃/min, and the invention is not limited to this.
The third aspect of the invention provides the silicon-carbon anode material prepared by the preparation method. The structure and the composition characteristics of the silicon-carbon anode material are as described above, and are not described in detail herein.
The fourth aspect of the invention provides an application of the silicon-carbon anode material in a lithium ion battery. The inventor of the invention finds that the silicon-carbon anode material provided by the invention is used in a lithium ion battery in the research process, so that the energy density of the lithium battery can be improved.
The fifth aspect of the invention provides a lithium ion battery, which comprises the silicon-carbon negative electrode material, the positive electrode material containing lithium element, a diaphragm and electrolyte.
The structure of the lithium ion battery provided by the invention can be known to those skilled in the art, and in general, the separator is positioned between the positive electrode sheet and the negative electrode sheet. The positive plate contains the positive electrode material, and the negative plate contains the silicon-carbon negative electrode material. The specific composition of the positive electrode material containing a lithium element is not particularly limited, and the positive electrode material containing a lithium element conventionally used in the art may be used.
According to the lithium ion battery provided by the invention, the separator can be selected from various separators used in lithium ion batteries known to those skilled in the art, and can be, for example, a polypropylene microporous membrane, a polyethylene felt, a glass fiber felt or ultrafine glass fiber paper.
According to the lithium ion battery provided by the invention, the electrolyte can be various conventional electrolytes, such as a nonaqueous electrolyte. The nonaqueous electrolytic solution is a solution of an electrolyte lithium salt in a nonaqueous solvent, and a conventional nonaqueous electrolytic solution known to those skilled in the art can be used. For example, the electrolyte may be selected from lithium hexafluorophosphate (LiPF) 6 ) Lithium perchlorate (LiClO) 4 ) Lithium tetrafluoroborate (LiBF) 4 ) Lithium hexafluoroarsenate (LiAsF) 6 ) And lithium hexafluorosilicate (LiSiF) 6 ) At least one of them. The nonaqueous solvent may be selected from a mixed solution of a chain acid ester and a cyclic acid ester, wherein the chain acid ester may be at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC) and dipropyl carbonate (DPC). The cyclic acid ester may be at least one of Ethylene Carbonate (EC), propylene Carbonate (PC) and Vinylene Carbonate (VC).
The present invention will be described in detail by examples. In the following examples and comparative examples, the morphology of the silicon carbon negative electrode material was characterized using a scanning electron microscope, specifically, a model TECNALG2F20 (200 kv) from FEI corporation, usa, test conditions: the sample was directly pressed against the sample stage containing the conductive tape and then observed by inserting an electron microscope. The observations were at 8000 x magnification. The content of each component is obtained by measuring the loss amount of the carbon source precursor under the roasting condition and calculating the feeding ratio.
In the following examples and comparative examples, electrochemical performance of assembled lithium ion batteries was tested using the marchantia-blue electric battery test system (CT 2001B). The test conditions included: the voltage range is 0.005V-3V, and the current range is 0.05A-2A. 10 coin cells were assembled for each sample, and cell performance was measured at the same voltage and current, and averaged.
In the following examples and comparative examples, coal tar pitch was commercially available from Longxin Material trade Co., ltd, under the trade designation low temperature pitch (100-115), 35% by weight carbon residue, medium temperature pitch (145-150) and 50% by weight carbon residue.
In the following examples and comparative examples, the room temperature refers to 25 ℃.
Among them, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, and sodium alginate are commercially available from the company a Ding Shiji.
Example 1
(1) Slowly adding 1g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon powder, and stirring for 4h.
(2) 50g (mass fraction 4 wt%) of an ethanol solution of polyacrylic acid with a weight average molecular weight of 240000 is taken, 10g of flake graphite (shown in figure 1) is added, and stirred at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, and stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) And (3) placing the above dry solid (shown in figure 2) subjected to suction filtration into a 200ml ball milling tank, adding 2g of medium-temperature asphalt, ball milling for 30min, placing the obtained solid into a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30min in a nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon anode material S-1. The composition of the silicon carbon negative electrode material S-1 is shown in Table 1.
Fig. 1 is an SEM photograph of the crystalline flake graphite, and fig. 2 is an SEM photograph of carbon silicon particles coated with a silicon-containing material layer. As can be seen from comparing fig. 1 and fig. 2, the surface of the carbonaceous material has uniformly coated the silicon nanoparticles through the step (2). Fig. 3 is an SEM photograph of the obtained silicon carbon negative electrode material, and comparing fig. 2, it can be seen that the surface of the particles coated with the silicon-containing material layer has been uniformly coated with pitch pyrolytic carbon, and the sphericity of the coated material is better, and the median particle diameter is about 22 μm.
The silicon carbon negative electrode material S-1 and the metal lithium sheet obtained in example 1 were used as a positive electrode and a negative electrode, respectively, and 1mol/L LiPF was used 6 The solution (ethylene carbonate and diethyl carbonate are mixed in a volume ratio of 3:7 to be used as a solvent) is used as an electrolyte, a polypropylene microporous membrane is used as a diaphragm, and the electrolyte is assembled into a CR2016 button cell, and the lithium-containing silicon-carbon anode material S-1 is characterized in the embodimentIs a cyclic stability property of (c).
Fig. 4 is a cycle stability test curve (discharge current of 0.5C) of a coin cell based on the lithium-containing silicon-carbon negative electrode material S-1 described in example 1. As can be seen from fig. 4, the capacity retention rate of the silicon-carbon negative electrode material S-1 described in example 1 is greater than 80% after 550 cycles at a constant current discharge rate of 0.5C.
Comparative example 1
(1) Slowly adding 1g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon powder, stirring for 4h and vacuum filtering.
(2) Placing the above dry solid in a 200ml ball milling tank, adding 2g of medium temperature asphalt, ball milling for 30min, placing the obtained solid in a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30min in nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon negative electrode material D-1.
Batteries were assembled and tested for electrical properties according to the method of example 1, except that S-1 was replaced with the material D-1 prepared in comparative example 1. Fig. 5 is a cycle stability test curve of a coin cell based on the material described in comparative example 1. As shown, the material of comparative example 1 had a capacity retention of only 60% after 100 cycles at a constant current discharge rate of 0.5C.
Comparative example 2
(1) Slowly adding 1g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon powder, and stirring for 4h.
(2) 50g (weight fraction 4 wt%) of ethanol solution of polyacrylic acid with weight average molecular weight of 240000 is taken, 10g of flake graphite is added, and stirred at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, and stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) And (3) placing the suction filtration drying solid into a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30 minutes in a nitrogen atmosphere, and naturally cooling to room temperature after the completion of the heat preservation, thus obtaining the silicon-carbon negative electrode material D-2.
Batteries were assembled and tested for electrical properties according to the method of example 1, except that the silicon carbon negative electrode material S-1 was replaced with the material prepared in comparative example 2. Fig. 7 is a cycle stability test curve of a coin cell based on the material described in comparative example 2. The results show that the material of comparative example 2 has a capacity retention of about 40% after 100 cycles at a constant current discharge rate of 0.5C.
Example 2
(1) Slowly adding 0.5g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon powder, and stirring for 4h.
(2) 50g (weight fraction 4 wt%) of ethanol solution of polyacrylic acid with weight average molecular weight of 240000 is taken, 10g of needle coke is added, and stirred at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, and stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) Placing the above dry solid obtained by suction filtration into a 200ml ball milling tank, adding 4g of medium-temperature asphalt, ball milling for 30min, placing the obtained solid into a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30min in a nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon anode material S-2. The composition of the silicon carbon negative electrode material S-2 is shown in Table 1.
A battery was assembled and tested for electrical properties according to the method of example 1, except that the silicon carbon negative electrode material S-1 was replaced with the material prepared in example 2. The test results showed that the material of example 2 had a capacity retention of about 85% after 500 cycles at a constant current discharge rate of 0.5C.
Example 3
(1) Slowly adding 0.08g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon powder, and stirring for 4h.
(2) 50g (mass fraction 4 wt%) of ethanol solution of polyacrylic acid with weight average molecular weight of 240000 is taken, 10g (trade mark S-216) of artificial graphite is added, and stirred at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, and stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) Placing the above dry solid obtained by suction filtration into a 200ml ball milling tank, adding 1.6g of medium-temperature asphalt, ball milling for 30min, placing the obtained solid into a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30min in a nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon anode material S-3. The composition of the silicon carbon negative electrode material S-3 is shown in Table 1.
A battery was assembled and tested for electrical properties according to the method of example 1, except that the silicon carbon negative electrode material S-1 was replaced with the material prepared in example 3. The test results show that the material of example 3 has a capacity retention of about 82% after 600 cycles at a constant current discharge rate of 0.5C.
Example 4
(1) Slowly adding 2g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon powder, and stirring for 4h.
(2) 50g (weight fraction 4 wt%) of aqueous solution of sodium alginate with weight average molecular weight of 130000 is taken, 10g of crystalline flake graphite is added, and stirred at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, and stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) Placing the above-mentioned suction-filtered dry solid into a 200ml stirring tank, adding 2.6g of medium-temperature asphalt, stirring for 5min at 2000r/min, placing the obtained solid into a tube furnace, heating to 850 deg.C at 5 deg.C/min, heat-insulating for 30 min under nitrogen atmosphere, and naturally cooling to room temperature after finishing so as to obtain the invented silicon-carbon negative electrode material S-4. The composition of the silicon carbon negative electrode material S-4 is shown in Table 1.
A battery was assembled and tested for electrical properties according to the method of example 1, except that the silicon carbon negative electrode material S-1 was replaced with the material prepared in example 4. The test results showed that the material of example 4 had a capacity retention of about 85% after 400 cycles at a constant current discharge rate of 0.5C.
Example 5
(1) Slowly adding 0.8g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon powder, and stirring for 4h.
(2) 50g (mass fraction 4 wt%) of sodium carboxymethylcellulose aqueous solution with a weight-average molecular weight of 850000 are taken, 10g of flake graphite is added, stirred at room temperature until the solid is uniformly dispersed, then the solution obtained in the step (1) is added, stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) Placing the above dry solid obtained by suction filtration into a 200ml ball milling tank, adding 3g of medium-temperature asphalt, ball milling for 30min, placing the obtained solid into a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30min in a nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon anode material S-5. The composition of the silicon carbon negative electrode material S-5 is shown in Table 1.
Batteries were assembled and tested for electrical properties according to the method of example 1, except that the lithium-containing silicon-carbon negative electrode material S-1 was replaced with the material prepared in example 5. The test results show that the material of example 5 has a capacity retention of about 80% after 500 cycles at a constant current discharge rate of 0.5C.
Example 6
(1) Slowly adding 1g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon powder, and stirring for 4h.
(2) 50g (mass fraction 7 wt%) of polyacrylic acid ethanol solution with weight average molecular weight of 240000 is taken, 20g of flake graphite is added, stirring is carried out at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) Placing the above dry solid obtained by suction filtration into a 200ml ball milling tank, adding 5g of low-temperature asphalt, ball milling for 100min, placing the obtained solid into a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30min in a nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon anode material S-6. The composition of the silicon carbon negative electrode material S-6 is shown in Table 1.
A battery was assembled and tested for electrical properties according to the method of example 1, except that the silicon carbon negative electrode material S-1 was replaced with the material prepared in example 6. The test results showed that the material of example 6 had a capacity retention of about 83% after 600 cycles at a constant current discharge rate of 0.5C.
Example 7
(1) Slowly adding 2.5g of 20 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon powder, and stirring for 4h.
(2) 50g (15 weight percent) of polyacrylic acid ethanol solution with the weight average molecular weight of 240000 is taken, 15g of flake graphite is added, the mixture is stirred at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) Placing the above dry solid obtained by suction filtration into a 200ml ball milling tank, adding 5g of low-temperature asphalt, ball milling for 100min, placing the obtained solid into a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30 min in a nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon anode material S-7. The composition of the silicon carbon negative electrode material S-7 is shown in Table 1.
A battery was assembled and tested for electrical properties according to the method of example 1, except that the silicon carbon negative electrode material S-1 was replaced with the material prepared in example 7. The test results show that the material of example 7 has a capacity retention of about 80% after 300 cycles at a constant current discharge rate of 0.5C.
Example 8
(1) Slowly adding 1g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon powder, and stirring for 4h.
(2) 50g (mass fraction 6 wt%) of aqueous solution of sodium alginate with weight average molecular weight of 130000 is taken, 15g of crystalline flake graphite is added, and stirred at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, and stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) Placing the above dry solid obtained by suction filtration into a 200ml ball milling tank, adding 3g of low-temperature asphalt, ball milling for 100min, placing the obtained solid into a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30 min in a nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon anode material S-8. The composition of the silicon carbon negative electrode material S-8 is shown in Table 1.
A battery was assembled and tested for electrical properties according to the method of example 1, except that the silicon carbon negative electrode material S-1 was replaced with the material prepared in example 8. The test results show that the material of example 8 has a capacity retention of about 80% after 500 cycles at a constant current discharge rate of 0.5C.
Example 9
(1) Slowly adding 1g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of 150nm silicon oxide (SiOx, x=1.2) was stirred for 4h.
(2) 50g (mass fraction 4 wt%) of polyacrylic acid ethanol solution with weight average molecular weight of 240000 is taken, 10g (trade mark S-216) of artificial graphite is added, stirred at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) Placing the above dry solid in a 200ml ball milling tank, adding 2g of medium temperature asphalt, ball milling for 30min, placing the obtained solid in a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30min in nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon negative electrode material S-9. The composition of the silicon carbon negative electrode material S-9 is shown in Table 1.
A battery was assembled and tested for electrical properties according to the method of example 1, except that the silicon carbon negative electrode material S-1 was replaced with the material prepared in example 9. The test results showed that the material of example 9 had a capacity retention of about 85% after 600 cycles at a constant current discharge rate of 0.5C.
Example 10
(1) Slowly adding 1g of 50 wt% phytic acid water solution into 20ml of ethanol, stirring, and adding D 50 1g of a 200nm silicon-aluminum alloy (silicon content: about 20% by weight) was stirred for 4 hours.
(2) 50g (mass fraction 4 wt%) of polyacrylic acid ethanol solution with weight average molecular weight of 240000 is taken, 10g (trade mark S-216) of artificial graphite is added, stirred at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) Placing the above dry solid in a 200ml ball milling tank, adding 2g of medium temperature asphalt, ball milling for 30min, placing the obtained solid in a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30min in nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon negative electrode material S-10. The composition of the silicon carbon negative electrode material S-10 is shown in Table 1.
A battery was assembled and tested for electrical properties according to the method of example 1, except that the silicon carbon negative electrode material S-1 was replaced with the material prepared in example 10. The test results showed that the material of example 10 had a capacity retention of about 85% after 500 cycles at a constant current discharge rate of 0.5C.
Example 11
(1) D is taken out 50 1g of 150nm silicon powder is slowly added into 20ml of ethanol and stirred for 4h.
(2) 50g (weight fraction 4 wt%) of polyacrylic acid ethanol solution with weight average molecular weight of 240000 is taken, 10g of flake graphite is added, stirring is carried out at room temperature until the solid is uniformly dispersed, then the solution in the step (1) is added, stirring is continued for 1h after the addition is finished, and vacuum filtration is carried out.
(3) Placing the above dry solid obtained by suction filtration into a 200ml ball milling tank, adding 2g of medium-temperature asphalt, ball milling for 30min, placing the obtained solid into a tube furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 30min in a nitrogen atmosphere, and naturally cooling to room temperature after finishing to obtain the silicon-carbon anode material S-11.
A battery was assembled and tested for electrical properties according to the method of example 1, except that the silicon carbon negative electrode material S-1 was replaced with the material prepared in example 11. Fig. 6 is a cycle stability test curve for coin cells based on the material described in example 11. The results show that the material of example 11 has a capacity retention of about 70% after 100 cycles at a constant current discharge rate of 0.5C.
TABLE 1
Note that: the median particle diameter is the median particle diameter of the silicon-carbon anode material.
According to the embodiment and the results, the silicon-carbon negative electrode material provided by the invention can obviously improve the cycle stability of the silicon-carbon negative electrode material, and can be applied to a lithium ion battery to improve the energy density of the lithium battery.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims (33)

1. The silicon-carbon negative electrode material is characterized by comprising a carbon-containing substance, and a silicon-containing material layer and an amorphous carbon layer which are sequentially coated on the outer surface of the carbon-containing substance;
the mass ratio of the carbonaceous substance, the amorphous carbon layer and the silicon-containing material is 1-20:0.8-2:1, a step of; the silicon-containing material layer also contains phosphorus element; in the silicon-carbon anode material, the mass ratio of phosphorus element to silicon-containing material is 0.01-0.28:1, a step of;
the silicon-carbon anode material is prepared by the following preparation method:
the step (1) comprises:
(1-1) mixing a silicon source and a phosphorus source in the presence of a solvent to obtain a solution A; the mass ratio of the phosphorus source to the silicon source calculated by phosphorus element is 0.01-0.28:1, a step of;
(1-2) mixing a carbonaceous material with a chain polymer solution, then adding the solution a thereto, and separating the resulting mixture to obtain a solid material; the chain polymer is used in an amount of 0.1 to 1 part by weight relative to 1 part by weight of the carbonaceous material;
the step (2) comprises: blending the solid substance with a carbon source precursor, and then roasting;
the mass ratio of the carbon-containing substance, the carbon source precursor calculated by carbon element and the silicon source is 1-20:0.8-2:1, a step of;
Wherein the carbonaceous material is selected from at least one of natural graphite, artificial graphite and needle coke;
the carbon source precursor is at least one selected from asphalt, polyacrylonitrile, phenolic resin, epoxy resin, polyfurfuryl alcohol, glucose and cellulose; the chain polymer contains at least one of carboxyl, hydroxyl, ester and amide; the silicon source is selected from at least one of elemental silicon, siOx and silicon-containing alloys, wherein 0.6< x <1.5; the phosphorus source is polyphosphoric acid.
2. The silicon-carbon negative electrode material of claim 1, wherein the silicon-containing material is selected from at least one of elemental silicon, siOx, and a silicon-containing alloy, wherein 0.6< x <1.5.
3. The silicon-carbon negative electrode material according to claim 1 or 2, wherein the silicon-containing alloy is selected from at least one of a silicon-aluminum alloy, a silicon-magnesium alloy, a silicon-zirconium alloy, and a silicon-boron alloy;
the silicon-containing material is elemental silicon and/or a silicon-aluminum alloy.
4. The silicon-carbon negative electrode material of claim 1, wherein the silicon-containing material has a median particle diameter of 0.1-5 μιη.
5. The silicon-carbon negative electrode material according to claim 1, wherein the mass ratio of phosphorus element to silicon-containing material in the silicon-carbon negative electrode material is 0.07-0.15:1.
6. The silicon-carbon negative electrode material of claim 1, wherein the mass ratio of the carbonaceous matter, the amorphous carbon layer, and the silicon-containing material is 10-15:1-1.3:1.
7. the silicon-carbon negative electrode material as claimed in claim 1, wherein the silicon-carbon negative electrode material has a median particle diameter of 1-50 μm.
8. The silicon-carbon negative electrode material of claim 7, wherein the silicon-carbon negative electrode material has a median particle diameter of 5-25 μιη.
9. The silicon-carbon negative electrode material of claim 1, wherein the natural graphite is crystalline flake graphite.
10. The silicon-carbon negative electrode material of claim 1, wherein the carbonaceous matter is crystalline flake graphite and/or needle coke.
11. The silicon-carbon negative electrode material of claim 1, wherein the amorphous carbon layer is obtained by firing a carbon source precursor.
12. A preparation method of a silicon-carbon anode material, which comprises the following steps:
the step (1) comprises:
(1-1) mixing a silicon source and a phosphorus source in the presence of a solvent to obtain a solution A; the mass ratio of the phosphorus source to the silicon source calculated by phosphorus element is 0.01-0.28:1, a step of;
(1-2) mixing a carbonaceous material with a chain polymer solution, then adding the solution a thereto, and separating the resulting mixture to obtain a solid material; the chain polymer is used in an amount of 0.1 to 1 part by weight relative to 1 part by weight of the carbonaceous material;
The step (2) comprises: blending the solid substance with a carbon source precursor, and then roasting;
the mass ratio of the carbon-containing substance, the carbon source precursor calculated by carbon element and the silicon source is 1-20:0.8-2:1, a step of;
wherein the carbonaceous material is selected from at least one of natural graphite, artificial graphite and needle coke;
the carbon source precursor is at least one selected from asphalt, polyacrylonitrile, phenolic resin, epoxy resin, polyfurfuryl alcohol, glucose and cellulose; the chain polymer contains at least one of carboxyl, hydroxyl, ester and amide; the silicon source is selected from at least one of elemental silicon, siOx and silicon-containing alloys, wherein 0.6< x <1.5; the phosphorus source is polyphosphoric acid.
13. The method of claim 12, wherein the natural graphite is flake graphite.
14. The method of claim 13, wherein the carbonaceous material is crystalline flake graphite and/or needle coke.
15. The preparation method of claim 12, wherein the chain polymer is at least one selected from polyacrylic acid, polyacrylate, sodium alginate, polyurethane and sodium carboxymethyl cellulose.
16. The method of claim 15, wherein the chain polymer is polyacrylic acid.
17. The production method according to any one of claims 12 to 16, wherein the chain polymer has a weight average molecular weight of 2000 to 5000000.
18. The production method according to claim 17, wherein the chain polymer has a weight average molecular weight of 80000 to 300000.
19. The production method according to claim 12, wherein the chain polymer is used in an amount of 0.1 to 0.5 parts by weight relative to 1 part by weight of the carbonaceous matter.
20. The production method according to claim 12, wherein the concentration of the chain-like polymer solution is 3 to 20% by weight.
21. The production method according to claim 12, wherein the silicon-containing alloy is at least one selected from a silicon-aluminum alloy, a silicon-magnesium alloy, a silicon-zirconium alloy, and a silicon-boron alloy.
22. The method of claim 21, wherein the silicon source is elemental silicon and/or a silicon-aluminum alloy.
23. The method of claim 12, wherein the silicon source has a median particle size of 0.1-5 μm.
24. The method of claim 12, wherein the phosphorus source is phytic acid.
25. The production method according to claim 12, wherein a mass ratio of the phosphorus source to the silicon source in terms of phosphorus element is 0.07 to 0.15:1.
26. The production method according to claim 12, wherein the carbon source precursor is at least one of pitch, polyacrylonitrile, and phenol resin.
27. The production method according to claim 12, wherein a mass ratio of the carbonaceous matter, the carbon source precursor in terms of carbon element, and the silicon source is 10 to 15:1-1.3:1.
28. the method of claim 12, wherein the blending of step (2) comprises at least one of solid ball milling, spray drying, and shear dispersing.
29. The method of claim 12, wherein the firing conditions of step (2) include: under inert atmosphere, the temperature is 600-1000 ℃ and the time is 10-240min.
30. The method of claim 29, wherein the firing conditions of step (2) comprise: under inert atmosphere, the temperature is 700-900 ℃; the time is 20-60min.
31. Use of the silicon-carbon negative electrode material as claimed in any one of claims 1 to 11 in a lithium ion battery.
32. A lithium ion battery comprising the silicon-carbon negative electrode material of any one of claims 1 to 11, a positive electrode material containing a lithium element, a separator, and an electrolyte.
33. The lithium ion battery of claim 32, wherein the lithium ion battery is a liquid lithium ion battery, a semi-solid lithium ion battery, or an all-solid lithium ion battery.
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