CN117638049A - Negative electrode active material for battery, preparation method of negative electrode active material, electrode and battery - Google Patents
Negative electrode active material for battery, preparation method of negative electrode active material, electrode and battery Download PDFInfo
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- CN117638049A CN117638049A CN202311838509.9A CN202311838509A CN117638049A CN 117638049 A CN117638049 A CN 117638049A CN 202311838509 A CN202311838509 A CN 202311838509A CN 117638049 A CN117638049 A CN 117638049A
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- Prior art keywords
- active material
- particles
- anode active
- silica compound
- porous silica
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- 239000007773 negative electrode material Substances 0.000 title claims abstract description 56
- 238000002360 preparation method Methods 0.000 title abstract description 6
- 239000002245 particle Substances 0.000 claims abstract description 168
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- 239000000377 silicon dioxide Substances 0.000 claims abstract description 94
- -1 silica compound Chemical class 0.000 claims abstract description 88
- 239000006183 anode active material Substances 0.000 claims abstract description 76
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 63
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- 238000000034 method Methods 0.000 claims description 58
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- 229910052744 lithium Inorganic materials 0.000 claims description 39
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- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
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- 229910052759 nickel Inorganic materials 0.000 description 1
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- 239000011301 petroleum pitch Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
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- 239000004584 polyacrylic acid Substances 0.000 description 1
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- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
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- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 235000011181 potassium carbonates Nutrition 0.000 description 1
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 1
- 229910052939 potassium sulfate Inorganic materials 0.000 description 1
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- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
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- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- 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
Landscapes
- Battery Electrode And Active Subsutance (AREA)
Abstract
The application provides a negative electrode active material for a battery, a preparation method of the negative electrode active material, an electrode and the battery. The anode active material includes anode active material particles; the anode active material particles comprise porous silica compound particles and a carbon film layer, the porous silica compound particles comprise micropores, the pore diameter of the micropores is less than 2nm, and Kong Rong 0.25.25 cm of the porous silica compound particles 3 And/g, the surface of the porous silica compound particles is partially or completely covered by a carbon film layer. The cathode active material for the battery provided by the invention has the electrochemical characteristics of high compacted density, small expansion and high energy density when in use. The battery prepared by the negative electrode active material has the advantages of low expansion, high energy density, excellent cycle performance and the like.
Description
Technical Field
The application relates to the field of batteries, in particular to a negative electrode active material for a battery, a preparation method of the negative electrode active material, an electrode and the battery.
Background
In recent years, with the development of various portable electronic devices and electric vehicles, there is an increasing demand for batteries having high energy density and long cycle life. The current commercial lithium ion battery cathode active material is mainly graphite, but the theoretical capacity is low (372 mAh/g), so that the further improvement of the battery energy density is limited. The simple substance silicon anode active material has high capacity advantage (lithium is intercalated into Li at room temperature) 15 Si 4 The theoretical lithium storage capacity is about 3600 mAh/g), is about 10 times of the theoretical capacity of the current commercial graphite anode active material, has the advantage of high capacity which cannot be compared with other anode active materials, becomes a research and development hot spot in academia and industry for many years, and gradually goes from laboratory research and development to commercial application.
Currently, three main types of silicon negative electrode active materials are developed, namely, single-substance silicon (comprising nano silicon, porous silicon, amorphous silicon and the like) and composite materials of the single-substance silicon and the same carbon material; secondly, alloy materials formed by combining silicon with other metal (such as iron, manganese, nickel, chromium, cadmium, tin, copper and the like) and nonmetal (such as carbon, nitrogen, phosphorus, boron and the like) components; and thirdly, a silicon oxygen compound and a composite material of the silicon oxygen compound and the carbon material. Of the three structures, the theoretical capacity of the elemental silicon material is highest, and therefore the theoretical energy density is also highest. However, the elemental silicon anode active material has a serious volume effect in the lithium intercalation and deintercalation process, and the volume change rate is about 300%, so that the electrode material is pulverized and separated from the current collector. In addition, as the silicon anode active material continuously expands and contracts to continuously break in the charge and discharge process of the battery, a new SEI film can be formed when the generated fresh interface is exposed to the electrolyte, so that the electrolyte is continuously consumed, and the cycle performance of the electrode material is reduced. The above drawbacks severely limit the commercial application of elemental silicon cathodes.
The capacity of the silicon oxide is lower than that of the simple substance silicon anode active material due to more inactive substances; at the same time, however, the expansion of the silicon during circulation is effectively inhibited by the inactive phase due to the presence of these inactive components, so that its circulation stability is of significant advantage.
Silicone compounds also present particular problems. When the material is used for inserting lithium for the first time, the surface of the particles often generates thicker SEI film due to more side reactions with electrolyte; meanwhile, substances such as lithium silicate, lithium oxide and the like which cannot reversibly remove lithium are generated in the particles, so that irreversible loss of lithium ions in the battery is caused. The above two types of irreversible reactions result in a lithium ion battery with a negative electrode containing a silicon oxide having low initial coulombic efficiency, thereby limiting the improvement of the energy density of the whole battery. In addition, the silicon oxide has the problems of low ionic and electronic conductivity, low coulombic efficiency in the battery cycle process and the like.
On the other hand, although the volume change rate of the silicon-oxygen compound in the lithium intercalation and deintercalation process is obviously reduced compared with that of the simple substance silicon anode, the volume expansion rate of the silicon-oxygen compound under full lithium intercalation still reaches 170-200%, the improvement of the energy density of a full battery using the anode is greatly restricted, and meanwhile, the cycle stability is greatly influenced, so that the silicon-oxygen compound is one of the key problems to be solved in the industry.
The content of the background section is only what the applicant knows and is not representative of prior art in the field.
Disclosure of Invention
A first object of the present application is to provide a negative electrode active material for a battery, characterized by comprising negative electrode active material particles; the anode active material particles comprise porous silica compound particles and a carbon film layer, the porous silica compound particles comprise micropores, the pore diameter of the micropores is less than 2nm, and Kong Rong 0.25.25 cm of the porous silica compound particles 3 Preferably less than or equal to 0.2cm 3 And/g, the surface of the porous silica compound particles is partially or completely covered by the carbon film layer.
In some embodiments of the invention, the porous silica compound particles further comprise mesopores having a pore diameter of 2 to 50nm, preferably 2 to 30nm, more preferably 2 to 20nm.
In some embodiments of the present invention, the anode active material particles satisfy: d is not less than 0.75, preferably not less than 0.8; wherein d=d1/D2, D is the relative tap density of the anode active material particles, D1 is the tap density of the anode active material particles, and D2 is the tap density when the anode active material particles do not have pores.
In some embodiments of the present invention, the specific surface area of the anode active material is 0.1 to 15m 2 Preferably 0.3 to 10m 2 Preferably 0.3 to 6m 2 /g。
In some embodiments of the present invention, the anode active material particles further contain a lithium element in an amount of 0.1 to 20wt%, preferably 2 to 18wt%, more preferably 4 to 15wt%.
In some embodiments of the present invention, the porous silica compound particles have a silicon element content of 30 to 80wt%, preferably 35 to 65wt%, more preferably 40 to 65wt%.
In some embodiments of the invention, the porous silica compound particles have a median particle diameter of 0.2 to 20 μm, preferably 1 to 15 μm, more preferably 3 to 13 μm.
In some embodiments of the present invention, the anode active material particles further include elemental silicon nanoparticles dispersed within the anode active material particles, the elemental silicon nanoparticles having a median particle diameter of between 0.1 and 35nm, preferably between 0.5 and 20nm, more preferably between 1 and 15nm.
In some embodiments of the invention, the carbon film layer has a thickness of 0.001 to 5 μm, preferably 0.005 to 2 μm, more preferably 0.01 to 1 μm.
In some embodiments of the present invention, the carbon film layer accounts for 0.01 to 20wt%, preferably 0.1 to 15wt%, more preferably 1 to 12wt% of the anode active material particles.
In some embodiments of the invention, the coverage of the carbon film layer on the surface of the porous silica compound particles is equal to or greater than 90%, preferably equal to or greater than 95%.
A second object of the present invention is to provide an electrode comprising any of the above-described anode active materials.
A third object of the present invention is to provide a battery comprising the above electrode.
A fourth object of the present invention is to provide a method for preparing the anode active material of any one of the above, comprising the steps of:
directly depositing to obtain the porous silica compound particles; or co-depositing a silica compound and a pore-forming precursor, and then removing the pore-forming precursor to obtain the porous silica compound particles; and
the porous silica compound particles are carbon coated.
In some embodiments of the invention, the method further comprises:
and carrying out lithium doping on the porous silica compound particles coated with the carbon film layer.
The cathode active material for the battery provided by the invention has the electrochemical characteristics of high compacted density, small expansion and high energy density when in use. The battery prepared by the negative electrode active material has the advantages of low expansion, high energy density, excellent cycle performance and the like.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application, illustrate and explain the application and are not to be construed as limiting the application. In the drawings:
fig. 1 is a process flow diagram for preparing a negative active material according to an exemplary embodiment of the present application.
Fig. 2 is a process flow diagram for preparing a negative active material according to another exemplary embodiment of the present application.
Fig. 3 is an SEM image of porous silica particles made in accordance with an exemplary embodiment of the present application.
Fig. 4 is a pore size distribution diagram of a negative electrode active material prepared according to another exemplary embodiment of the present application.
Detailed Description
Hereinafter, only certain exemplary embodiments are briefly described. As will be recognized by those of skill in the pertinent art, the described embodiments may be modified in various different ways without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.
The following disclosure provides many different embodiments, or examples, for implementing the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.
Furthermore, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present invention and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In view of the measurements in question and the errors associated with the particular amounts of the measurements (i.e., limitations of the measurement system), as used herein "about" or "approximately" includes the stated values and is intended to be within the acceptable range of deviation from the particular values as determined by one of ordinary skill in the art. For example, "about" may mean within one or more standard deviations, or within ±30%, ±20%, ±10% or ±5% of the stated value.
The following detailed description of specific embodiments of the invention is provided in connection with the accompanying drawings and examples in order to provide a better understanding of the aspects of the invention and advantages thereof. However, the following description of specific embodiments and examples is for illustrative purposes only and is not intended to be limiting of the invention.
[ negative electrode active material ]
The present invention proposes a negative electrode active material for a battery, which has negative electrode active material particles. Wherein the anode active material particles include porous silica compound particles and a carbon film layer, and the surfaces of the porous silica compound particles are partially or completely covered with the carbon film layer. The porous silica compound particles comprise micropores, and the pore diameter of the micropores is less than 2nm. Optionally, the porous silica compound particles may further comprise mesopores, which may have a pore diameter of 2 to 50nm, preferably 2 to 30nm, more preferably 2 to 20nm. That is, the porous silica compound particles of the present invention have a pore diameter of 50nm or less, preferably 30nm or less, more preferably 20nm or less.
According to the invention, the pores in the porous silica compound particles can effectively accommodate partial volume expansion of silicon in the lithium intercalation process, so that the volume change rate of the particles in the lithium intercalation and deintercalation process is reduced, and the damage degree of the particles in the repeated expansion and contraction process is reduced. Meanwhile, in the circulation process, repeated damage and rapid thickening of the SEI film can be effectively inhibited, the consumption, the cyclic expansion and the internal resistance increase amplitude of active lithium ions after the battery is charged and discharged for many times are reduced, and the service life and the stability of the battery are improved.
In the invention, the pore diameter of the porous silica compound particles is less than or equal to 50nm, preferably less than or equal to 30nm, more preferably less than or equal to 20nm, so that the structural uniformity of the inside of the anode active material particles can be improved, on one hand, the mechanical strength of the anode active material particles is improved, the breakage of the anode active material particles in the rolling process of the electrode plates is avoided, the bearable compaction density of the electrode plates is improved, on the other hand, the effective utilization rate of pores in the particles is also improved, the volume expansion of the particles in the lithium intercalation process is effectively absorbed, the internal stress of the particles is effectively released, and the volume change rate and the damage degree of the particles in the charge-discharge process are reduced. Therefore, the energy density and the cycle stability of the material are effectively improved. When the particles contain micropores, the uniformity of pore distribution in the particles is further improved, and the effective utilization rate of the pores is also further improved, so that the above excellent effects can be better amplified.
In the present invention, kong Rong 0.25.25 cm of porous silica compound particles 3 Preferably less than or equal to 0.2cm 3 And/g. In the pore volume range, the pore volume ratio of the porous silica compound is relatively balanced, so that the functions of accommodating the volume expansion of the silicon negative electrode and reducing SEI damage can be realized, and the reduction of the mechanical strength of particles and the loss of the volumetric specific energy can be avoided. The mechanical strength of the porous silica compound particles greatly affects the compaction density of the negative electrode plate using the negative electrode active material, and the negative electrode plate needs to avoid the situation that the negative electrode active particles are crushed and broken or damaged in the rolling process, otherwise, obvious electrical failure and continuous side reaction can occur in the battery, and the circulation stability is affected. Therefore, the porous silica compound particles need to ensure sufficient mechanical strength to ensure that the negative electrode sheet using the negative electrode active material can withstand a larger compacted density and ensure an improvement in energy density thereof.
In the present invention, the anode active material particles satisfy: d is not less than 0.75, preferably not less than 0.8. Where d=d1/D2, D is the relative tap density of the anode active material particles, D1 is the tap density of the anode active material particles, and D2 is the tap density of the silicon-containing material whose core is void-free and whose other structure is consistent with the anode active material particles (i.e., the tap density when the anode active material particles of the present invention are void-free). In the range of the relative tap density, the pore volume of the porous silica compound is relatively balanced, so that the functions of accommodating the volume expansion of the silicon negative electrode and reducing SEI damage can be realized, and the reduction of the mechanical strength of particles and the loss of the volumetric specific energy can be avoided.
In the present invention, the specific surface area of the anode active material particles may be 0.1 to 15m 2 Preferably 0.3 to 10m 2 Preferably 0.3 to 6m 2 And/g. Within the above specific surface area range, less side reactions occur on the surface of the anode active material particles, and the stability is high.
In the present invention, the anode active material particles further contain lithium element, and the content of the lithium element may be 0.1 to 20wt%, preferably 2 to 18wt%, more preferably 4 to 15wt%.
In the present invention, the silicon element content of the silicon oxide particles may be 30 to 80wt%, preferably 35 to 65wt%, more preferably 40 to 65wt%, and thus the negative electrode active material of the present invention has a high reversible capacity.
In the present invention, the silicone compound particles may have a median particle diameter of 0.2 to 20. Mu.m, preferably 1 to 15. Mu.m, more preferably 3 to 13. Mu.m.
The anode active material particles of the present invention may further contain elemental silicon nanoparticles, which may be uniformly dispersed in the anode active material particles. Wherein, the median particle diameter of the simple substance silicon nano particles can be between 0.1 and 35nm, preferably between 0.5 and 20nm, and more preferably between 1 and 15nm. The particles undergo little expansion and are not easy to break when undergoing the cycle of lithium ion intercalation and deintercalation, so that the lithium ion secondary battery using the material has little cyclic expansion and stable cycle.
In the present invention, the thickness of the carbon film layer may be 0.001 to 5. Mu.m, preferably 0.005 to 2. Mu.m, more preferably 0.01 to 1. Mu.m. The existence of the carbon film layer can effectively improve the conductivity of particles, reduce the contact resistance among particles in the negative electrode plate and between the negative electrode plate and the current collector, thereby improving the lithium removal efficiency of the material, reducing the polarization of the lithium ion battery and promoting the cycling stability of the lithium ion battery.
Further, the carbon film layer may be present in the anode active material particles in an amount of 0.01 to 20wt%, preferably 0.1 to 15wt%, more preferably 1 to 12wt%.
Further, the coverage of the carbon film layer on the surface of the porous silica compound particles is more than 90%, preferably more than 95%. The higher the coverage rate of the carbon film layer on the surface of the porous silica compound particles is, the more direct contact between the porous particles and the electrolyte can be effectively isolated, and the adverse effect caused by the larger specific surface area of the porous particles is greatly reduced. The coverage rate of the carbon film layer is high, the specific surface area of the anode active material particles containing porous particles can be reduced, the side reaction of materials and electrolyte is reduced, and the stability of the anode active material particles in a battery is improved.
The negative electrode active material for the battery has the electrochemical characteristics of high compacted density, high energy density and small expansion when being used. The battery prepared by the negative electrode active material has the advantages of low expansion, high energy density, excellent cycle performance and the like.
[ method for producing negative electrode active material ]
Fig. 1 is a view showing a method for preparing a negative active material according to an exemplary embodiment of the present invention.
S101: porous silica compound particles were prepared.
In this step, the porous silica compound particles can be produced by: 1) Directly depositing to obtain porous silica compound particles; or 2) co-depositing the silica compound and the pore-forming precursor, and then removing the pore-forming precursor to obtain porous silica compound particles.
The specific process of the first preparation mode can be carried out by the following steps:
first, a mixture of metal silicon powder and silica powder is heated at a temperature ranging from 900 ℃ to 1600 ℃ under an inert gas atmosphere or a reduced pressure, thereby generating a silica gas, and the molar ratio of the metal silicon powder to the silica powder is set to be in the range of 0.5 to 1.5. The gas generated by the heating reaction of the raw materials is deposited on the adsorption plate at a specific temperature (i.e., deposition temperature). Taking out the sediment when the temperature in the reaction furnace is reduced to below 100 ℃, and crushing and powdering the sediment by using a ball mill, a jet mill and other equipment to obtain silicon oxide particles.
The inventors have found that silicon oxide particles having different specific surface areas can be obtained by adjusting the degree of vacuum, the molar ratio of the metal silicon powder to the silicon dioxide powder, and the temperature of the adsorption plate in the above reaction process. The silica compound particles with significantly larger specific surface area are porous structures and contain micropores, and the porous silica compound particles can be obtained by using corresponding reaction parameters. In the reaction process, normal pressure reaction conditions or vacuum decompression reaction conditions can be selected, wherein the vacuum degree is more than or equal to 1Pa. By adjusting the ratio of the metal silicon powder to the silicon dioxide powder, the reaction process speed is influenced, so that SiOx (x=0.5-1.5) with different silicon oxygen stoichiometry and micro-defect structures is obtained. In addition, the deposition temperature can be selected from room temperature to 1000 ℃, the deposition speeds at different deposition temperatures are different, and the crystal structure and the micro-defect structure of the silicon oxide obtained by deposition are also obviously different.
The specific process of the second preparation mode can be carried out by the following steps:
firstly, under the inert gas atmosphere or the reduced pressure condition, heating the mixture of metal silicon powder, silicon dioxide powder and pore-forming precursor in the temperature range of 900-1600 ℃, or mixing and heating the metal silicon powder and the silicon dioxide powder, and simultaneously heating the pore-forming precursor in another independent heating zone, wherein the heating temperature of the pore-forming precursor can be different from the heating temperature of the metal powder and the silicon dioxide powder. Thus, a mixture of silicon oxide and pore-forming precursor will be generated within the reaction chamber, which mixture will then be deposited on the adsorption plate at a specific temperature. Taking out the sediment when the temperature in the reaction furnace is reduced to below 100 ℃, and crushing and powdering the sediment by using a ball mill, a jet mill and other equipment to obtain silica compound particles containing a pore-forming precursor. And then cleaning the silica compound particles containing the pore-forming precursor by using water, ethanol, acid solution or alkali solution and the like, fully dissolving and washing the pore-forming precursor, and then drying to obtain the porous silica compound particles.
Alternatively, the pore-forming precursor is a soluble salt having a boiling point in the temperature range of 900 ℃ to 1600 ℃, such as sodium chloride, sodium carbonate, sodium sulfate, potassium chloride, potassium carbonate, potassium sulfate, lithium chloride, lithium carbonate, lithium sulfate, and the like.
Alternatively, the pore-forming precursor is a metal compound having a boiling point in the temperature range of 900 ℃ to 1600 ℃, and the metal compound is decomposed or reacted to generate gas in the silica compound particles, so that a porous structure is formed in the silica compound particles.
The porous silica compound particles comprise a silica (silicon monoxide and/or silicon dioxide) material. In an exemplary embodiment of the present invention, the silica stoichiometry in the porous silica compound particles may be 1:0.4 to 1:2, alternatively 1:0.6 to 1:1.5, and more alternatively 1:0.8 to 1:1.2. Of course, other trace amounts of impurity elements may be present in addition to silicon oxide.
S102: the porous silica compound particles are carbon coated.
According to an exemplary embodiment, the silica compound in the porous silica compound particles may be a silica compound that has not been disproportionated, or may be a silica compound that has been heat-treated by disproportionation. Wherein the disproportionation heat treatment temperature may be 600 to 1100 ℃, alternatively 700 to 1000 ℃, more preferably 800 to 1000 ℃.
In the present invention, the carbon film layer can be directly obtained by Chemical Vapor Deposition (CVD). The carbon source used for CVD is a hydrocarbon gas, and the decomposition temperature of the hydrocarbon gas may be 600 to 1100 ℃, preferably 700 to 1000 ℃, and more preferably 800 to 1000 ℃.
The carbon film layer may be obtained by coating carbon by a reaction and then carbonizing the carbon film layer by a heat treatment in a non-oxidizing atmosphere. The carbon reaction coating method can adopt any one of a mechanical fusion machine, a VC mixer, a coating kettle, spray drying, a sand mill or a high-speed dispersing machine, and the solvent selected during coating is one or a combination of more of water, methanol, ethanol, isopropanol, N-butanol, ethylene glycol, diethyl ether, acetone, N-methylpyrrolidone, methyl butanone, tetrahydrofuran, benzene, toluene, xylene, N-dimethylformamide, N-dimethylacetamide and chloroform. The carbon reaction source can be one or more of coal tar pitch, petroleum pitch, polyvinyl alcohol, epoxy resin, polyacrylonitrile, polymethyl methacrylate, glucose, sucrose, polyacrylic acid and polyvinylpyrrolidone. The equipment used for the heat treatment carbonization can be any one of a rotary furnace, a ladle furnace, a roller kiln, a pusher kiln, an atmosphere box furnace or a tube furnace. The carbonization temperature of the heat treatment may be 600 to 1100 ℃, preferably 700 to 1000 ℃, more preferably 800 to 1000 ℃, and the heat preservation time is 0.5 to 24 hours. The non-oxidizing atmosphere may be provided by at least one of the following gases: nitrogen, argon, hydrogen or helium.
The coating ratio of the carbon film layer on the surface of the porous silica particles is preferably 90% or more, more preferably 95% or more. Thus, a relatively complete and continuous carbon film coating layer can be formed on the surface of the porous particles, and the porous silica particles are well isolated and protected.
Fig. 2 illustrates a method of preparing a negative active material according to another exemplary embodiment of the present invention, including the steps of:
s201: porous silica compound particles were prepared.
S202: the porous silica compound particles are carbon coated.
S203: and carrying out lithium doping on the porous silica compound particles coated with the carbon film layer.
The steps S201 and S202 are similar to the steps S101 and S102, and will not be described again.
In step S203, the porous silica compound particles may be doped (intercalating lithium element) by electrochemical doping, liquid phase doping, thermal doping, or the like. The doping atmosphere of the lithium element is a non-oxidizing atmosphere composed of at least one of nitrogen, argon, hydrogen, or helium.
The method of inserting lithium element (lithium doping modification method) may be:
1) Electrochemical process
An electrochemical cell is provided comprising four components including a bath, an anode electrode, a cathode electrode, and a power source, wherein the anode electrode and the cathode electrode are respectively connected to two ends of the power source. At the same time, the anode electrode is connected to a lithium source, while the cathode electrode is connected to a container containing particles of a silicon oxygen compound. The bath is filled with an organic solvent, and a lithium source (anode electrode) and a container (cathode electrode) containing silicon oxide particles are immersed in the organic solvent. After the power is turned on, lithium ions are intercalated into the structure of the silicon oxide compound due to the occurrence of electrochemical reaction, and lithium doped modified silicon oxide compound particles are obtained. The organic solvent may be selected from ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, dimethyl carbonate, methylethyl carbonate, diethyl carbonate, ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, dimethyl sulfoxide, etc. In addition, the organic solvent also contains electrolyte lithium salt, lithium hexafluorophosphate (LiPF) 6 ) Lithium tetrafluoroborate (LiBF) 4 ) Lithium perchlorate (LiClO) 4 ) Etc. The above lithium source (anode electrode) may be a lithium foil, or a lithium compound such as lithium carbonate, lithium oxide, lithium hydroxide, lithium cobaltate, lithium iron phosphate, lithium manganate, lithium vanadium phosphate, lithium nickelate, or the like.
2) Liquid phase doping method
Adding metal lithium, electron transfer catalyst and silicon oxide particles into ether-based solvent, continuously stirring and heating in non-oxidizing atmosphere to keep constant temperature reaction until the metal lithium in the solution completely disappears. Under the action of an electron transfer catalyst, metallic lithium can be dissolved in an ether solvent to form a coordination compound of lithium ions, and the coordination compound has lower reduction potential, so that the coordination compound can react with a silicon oxide compound, and the lithium ions enter the structure of the silicon oxide compound. The electron transfer catalyst includes biphenyl, naphthalene, and the like. The ether-based solvent comprises methyl butyl ether, ethylene glycol butyl ether, tetrahydrofuran, ethylene glycol dimethyl ether and the like. The constant temperature reaction temperature is 25-200 ℃. The non-oxidizing atmosphere is provided by at least one of the following gases: nitrogen, argon, hydrogen or helium.
3) Thermal doping method
The silicon oxide particles are uniformly mixed with the lithium-containing compound and then heat-treated in a non-oxidizing atmosphere. The lithium-containing compound includes lithium hydroxide, lithium carbonate, lithium oxide, lithium peroxide, lithium hydride, lithium nitrate, lithium acetate, lithium oxalate, and the like. The mixing method adopts any one of a high-speed dispersing machine, a high-speed stirring mill, a ball mill, a conical mixer, a spiral mixer, a stirring mixer or a VC mixer. The equipment used for the heat treatment is any one of a rotary furnace, a ladle furnace, an inner container furnace, a roller kiln, a pusher kiln, an atmosphere box furnace or a tubular furnace. The temperature of the heat treatment is 400-850 ℃, preferably 550-800 ℃; the heat preservation time is 1-12 hours; the temperature rise rate is greater than 0.1 ℃ per minute and less than 10 ℃ per minute. The non-oxidizing atmosphere is provided by at least one of the following gases: nitrogen, argon, hydrogen or helium.
The step of embedding lithium element is performed after the carbon film coating, so that the growth of silicon grains in the silicon oxide can be inhibited in the heat treatment process. Therefore, the nano-level simple substance silicon particles are uniformly dispersed and fixed in the lithium silicate compound or silicon oxide matrix, so that the expansion of the silicon nano particles can be effectively inhibited, and the silicon particles are prevented from being gradually fused into particles with larger size in the charge and discharge process, so that the expansion deformation of a battery in the circulation process and the electrical failure of a silicon material are reduced, and the lithium ion secondary battery using the material has small and stable circulation expansion. In addition, the step of coating the carbon film layer is carried out before the lithium element is embedded, so that the carbon film layer with better quality and more complete coating is obtained.
[ method for characterizing negative electrode active material ]:
1. and (3) material detection: the negative electrode active materials prepared in each example and comparative example were characterized using the following equipment: the particle size distribution of the negative electrode active material was measured using a laser particle sizer of the BetterSize 2600 type, dendong, hundred. The surface morphology of the negative electrode active material was observed using a Hitachi SU8010 type Scanning Electron Microscope (SEM). The specific surface area and pore size distribution of the negative electrode active material were measured using a NOVA4200e type specific surface area tester of Quantachrome Instruments. Wherein the specific surface area is tested as follows: and weighing a sample by using a sample tube, testing a nitrogen adsorption and desorption curve by using nitrogen at a relative pressure=0.05-0.99, testing the specific surface area of the sample by a multipoint method, and obtaining the pore size distribution and pore volume by DFT fitting.
And testing the tap density of the obtained anode material by adopting a Dendrobaud BT-301 tap density tester. Wherein the tap density test requirements are as follows: preparing a 25ml measuring cylinder, fixing the measuring cylinder on a base of the equipment, aligning an origin on a sample table with the origin on the equipment, and screwing the base; then adding 10-20 g of sample powder, wherein the mass of the powder is recorded as m; the surface of the powder in the measuring cylinder is in a horizontal state as much as possible, and a rubber plug is plugged into the orifice of the measuring cylinder; then vibrating the sample 3000 times according to the vibration frequency of 200 Hz; after the test is finished, if the upper surface of the sample in the measuring cylinder is horizontal, directly reading V; if the surface of the sample in the measuring cylinder is not horizontal, reading the highest point V1 and the lowest point V2, and taking the average value V of the highest point V and the lowest point V; the tap density of the sample ρ=m/V is then obtained.
2. Homogenizing and preparing a pole piece: taking 10 parts of the negative electrode active material, 84 parts of artificial graphite, 2.5 parts of conductive additive and 3.5 parts of binder, carrying out homogenate coating under an aqueous system, and then drying and rolling to obtain the negative electrode plate containing the negative electrode active material. After rolling, observing the state of silicon-containing particles in the pole piece by a scanning electron microscope, and if the state that the particles are crushed and broken or broken appears, indicating that the compaction is too large, the compaction is not suitable for the silicon-containing particles, and the compaction density needs to be reduced. By testing, the maximum compacted density ρ of the anode active material suitable for the respective embodiments can be found m 。
3. Full cell evaluation: the negative electrode sheets of the negative electrode active materials prepared in each example and comparative example are cut, baked in vacuum, wound together with the paired ternary positive electrode sheet and diaphragm, and then put into an aluminum-plastic shell with corresponding size, a certain amount of electrolyte is injected, degassing and sealing are carried out, and a lithium ion full battery with about 3.2Ah is obtained after formation. Test the efficiency, capacity and energy of the full cell at 0.2C with a cell tester from Shenzhen New wile electronics IncAnd cycling stability at 1C. Meanwhile, full charge disassembly is performed under the condition that the full battery is fully charged for the first time, the thickness d of the negative electrode plate under full lithium intercalation is measured after disassembly, the original thickness of the negative electrode plate is d0, and therefore the full charge expansion rate of the corresponding negative electrode plate is defined as S, S= (d-d 0)/d 0 is 100%. Wherein the full voltage of the negative electrode sheet under the condition of full intercalation of lithium is defined as ρ, ρ=ρ m ×d0/d。
The present application is further described below in connection with specific embodiments.
Example 1-1
Metal silicon powder and silicon dioxide powder are mixed according to a mole ratio of 1.08:1, simultaneously adding sodium chloride accounting for 40 percent of the total mass of the metal silicon powder and the silicon dioxide, heating the mixture to 1200 ℃ under the vacuum degree of 1kPa, so that the mixture generates mixed gas of silicon oxide and sodium chloride, and then depositing the mixed gas on a depositing cylinder at 500 ℃ to obtain the silicon oxide containing sodium chloride. The above-mentioned deposit is pulverized and powdered by using a ball mill, a jet mill or the like to obtain silica particles containing sodium chloride.
And then, through the technological processes of multiple times of water washing, drying and the like, sodium chloride in the particles is sufficiently washed and removed, and porous silica compound particles are obtained.
1000 g of the porous silica compound particles described above were weighed and placed in a CVD furnace. And taking acetylene as a carbon source, and carrying out coating reaction at 950 ℃ to obtain the anode active material. Wherein the coverage rate of the carbon film layer reaches 98 percent. The specific surface area and pore size distribution of the material were measured by a specific surface area tester, the material was measured to have a pore size of 50nm (as shown in FIG. 3) and to have both micropores and mesopores, and the pore volume was measured to be 0.15g/cm 3 。
Taking 10 parts of the negative electrode active material, 84 parts of artificial graphite, 3.5 parts of conductive additive and 2.5 parts of binder, carrying out homogenate coating under an aqueous system, and then drying and rolling to obtain the silicon-containing negative electrode plate. The maximum density (ρ) that the pole piece can withstand m ) Is 1.58g/cm 3 At this compacted density, the anode active material particles in this embodiment are not destroyed by the rolling process.
The negative plate is matched with a ternary positive electrode to form a full battery, full charge disassembly is carried out under the condition of first full charge, the full charge expansion rate (S) of the negative plate is measured to be 22.3%, and the corresponding full charge compaction (rho) is measured to be 1.29g/cm 3 . Meanwhile, the Volumetric Energy Density (VED) of the full cell at 0.2C was 639.8Wh/L. See in particular table 1.
Examples 1 to 2
Silicon oxide containing sodium chloride was deposited by a process similar to that of example 1-1, the added mass of sodium chloride was adjusted to 27% of the total mass of the metal silicon powder and silicon dioxide, the deposition temperature was adjusted to 600 c, and then porous silicon oxide particles were obtained by a water-washing and drying process as well. And then adopting the same carbon coating process to obtain the anode active material. The anode active material particles in this embodiment are not damaged by the rolling process. Specific performance data are shown in table 1.
Examples 1 to 3
The process similar to that of examples 1-2 was adopted, and the added mass of sodium chloride was adjusted to 54% of the total mass of the metal silicon powder and silica, and the remaining processes were identical, to obtain a negative electrode active material. The anode active material particles in this embodiment are not damaged by the rolling process. Specific performance data are shown in table 1.
Examples 1 to 4
The process similar to that of examples 1-2 was adopted, and the added mass of sodium chloride was adjusted to 67% of the total mass of the metal silicon powder and silica, and the remaining processes were identical, to obtain a negative electrode active material. The anode active material particles in this embodiment are not damaged by the rolling process. Specific performance data are shown in table 1.
Comparative examples 1 to 1
Silicon oxide containing sodium chloride was deposited by a process similar to that of example 1-1, the vacuum degree was changed to normal pressure and nitrogen atmosphere only, the reaction temperature was adjusted to 1400℃and then porous silica compound particles were obtained by a water-washing and drying process as well. And then adopting the same carbon coating process to obtain the anode active material. Specific performance data are shown in table 1.
Comparative examples 1 to 2
Metal silicon powder and silicon dioxide powder are mixed according to a mole ratio of 1.08:1, and then heating the mixture to 1400 ℃ under the normal pressure of nitrogen atmosphere, so that the mixture generates silicon oxide gas, and then depositing the silicon oxide gas on a deposition cylinder at 800 ℃ to obtain the silicon oxide. The above-mentioned deposit is pulverized and powderized by using a ball mill, a jet mill or the like to obtain silica particles. Then, a carbon-coated process similar to that of example 1-1 was employed to obtain a negative electrode active material. Specific performance data are shown in table 1.
Comparative examples 1 to 3
The process similar to that of examples 1-2 was adopted, and the added mass of sodium chloride was adjusted to be 81% of the total mass of the metal silicon powder and silica, and the remaining processes were identical, to obtain a negative electrode active material. Specific performance data are shown in table 1.
TABLE 1
As can be seen from the above results, when the porous silica compound particles have micropores, the pore volume is controlled to be 0.25cm or less 3 Per g, further less than or equal to 0.2cm 3 And when the negative electrode active material is used for preparing the negative electrode, the pore volume ratio of the negative electrode active material is relatively balanced, the functions of accommodating the volume expansion of a silicon negative electrode and reducing SEI damage can be realized, the reduction of the mechanical strength of particles and the loss of the volumetric specific energy can be avoided, the negative electrode plate using the negative electrode active material can bear larger compaction density, and the improvement of the energy density of the negative electrode plate can be ensured.
Example 2-1
Similar to example 1-1, the addition amount of sodium chloride was adjusted to 19% of the total mass of the metal silicon powder and the silica, and the remaining processes were identical to obtain porous silica compound particles coated with a carbon film, which were then lithium-doped to obtain the product of this example.
Specifically, taking porous silica compound particles coated with a carbon film, mixing lithium-containing compounds (such as lithium oxide, lithium hydride, lithium hydroxide, lithium carbonate and the like), placing the mixed powder in an argon atmosphere for heat treatment, heating to 680 ℃ at a heating rate of 3 ℃ per minute for 3 hours, and naturally cooling to obtain the porous silica compound particles doped with the carbon film and the lithium. The coverage rate of the carbon film of the anode active material is 98 percent, the anode active material has the aperture of 50nm, and simultaneously has micropores and mesopores, and the pore volume is 0.07cm 3 And/g, the relative tap density (D) is 0.88.
Maximum sustainable compaction density (ρ) of negative electrode sheet containing the negative electrode active material m ) Is 1.6g/cm 3 The full electrical expansion (S) of the negative electrode sheet in the full cell was 22.7%, and the corresponding full electrical compaction (ρ) was 1.3g/cm 3 The Volumetric Energy Density (VED) at 0.2C of the full cell containing the negative electrode was 684.6Wh/L, and the retention rate of the full cell after 1000 cycles was 83.2%. See in particular table 2.
Example 2-2
Similarly to example 1-2, the addition amount of sodium chloride was adjusted to 19% of the total mass of the metal silicon powder and the silicon dioxide, and the remaining processes were identical, to obtain porous silicon oxide particles coated with a carbon film, which was lithium-doped in the same manner as in example 2-1 to obtain the anode active material of this example. Specific performance data are shown in table 2.
Examples 2 to 3
Example 2-3 the method similar to example 1-1 was used, but the amount of sodium chloride added was adjusted to 19% of the total mass of the metal silicon powder and silicon dioxide, the deposition temperature was adjusted to 650 c, and the vacuum degree was increased to 600Pa, and the porous silica compound particles coated with the carbon film were obtained after the same steps of crushing, washing with water, drying, and carbon coating.
Next, the above silicon oxide powder, metallic lithium tape and biphenyl were charged into a sealable glass vessel, and then methyl butyl ether was added and the reaction was stirred under an argon atmosphere. After the reaction is finished and the powder is dried, the obtained powder is placed in an argon atmosphere for heat treatment, the temperature is raised to 700 ℃ at a temperature raising speed of 5 ℃ per minute, the heat is preserved for 2 hours, and then the lithium-doped anode active material can be obtained after natural cooling. Specific performance data are shown in table 2.
Examples 2 to 4
Examples 2-4 were prepared by a method similar to examples 2-3, but replacing the pore-forming precursor with potassium chloride, and subjecting the same to crushing, washing and drying, carbon-coating, lithium doping, and the like to obtain a negative electrode active material. Specific performance data are shown in table 2.
Examples 2 to 5
Examples 2 to 5 were prepared by a method similar to that of examples 2 to 3, but replacing the pore-forming precursor with lithium chloride, and subjecting the same to the steps of crushing, washing with water, drying, carbon-coating, lithium doping, and the like to obtain a negative electrode active material. Specific performance data are shown in table 2.
Examples 2 to 6
Metal silicon powder and silicon dioxide powder are mixed according to a mole ratio of 1.15:1, and then heating the mixture to 1250 ℃ under a vacuum degree of 133Pa, so that the mixture generates a silicon oxide gas, and then depositing the silicon oxide gas on a deposition cylinder at normal temperature. The above-mentioned deposit is pulverized and powdered by using a ball mill, a jet mill or the like to obtain silicone compound particles. The silica compound has a significantly increased specific surface area, as characterized by a specific surface area tester, and contains micropores (as shown in fig. 4). The porous silica compound particles were subjected to the carbon-coated lithium-doped process steps similar to those of example 2-1, to obtain a negative electrode active material. Specific performance data are shown in table 2.
Comparative example 2-1
Comparative example 2-1 by using a process similar to that of example 2-1, only the process of depositing sodium chloride-containing silica was changed to normal pressure and nitrogen atmosphere, and then the negative electrode active material was obtained after the same process steps of crushing, washing with water, drying, carbon inclusion, lithium doping, and the like. Specific performance data are shown in table 2.
Comparative examples 2 to 2
Comparative example 2-2 the process similar to example 2-2 was used, and only the process of depositing sodium chloride-containing silica was changed to normal pressure and nitrogen atmosphere, followed by the same process steps of crushing, washing with water, drying, carbon inclusion, lithium doping, and the like, to obtain a negative electrode active material. Specific performance data are shown in table 2.
Comparative examples 2 to 3
Comparative example 2-3 the method similar to example 2-1 was used, but the pore-forming precursor was replaced with lithium carbonate, and the negative electrode active material was obtained after the same process steps of crushing, washing with water, drying, carbon-coating, lithium doping, and the like. Specific performance data are shown in table 2.
Comparative examples 2 to 4
Comparative examples 2-4 the method similar to example 2-1 was used, but the pore-forming precursor was replaced with sodium sulfate, and the negative electrode active material was obtained after the same procedures of crushing, washing with water, drying, carbon-coating, lithium doping, and the like. Specific performance data are shown in table 2.
Comparative examples 2 to 5
Comparative example 2-5 is similar to example 2-1, the only difference being the absence of carbon film. The performance data of the obtained anode active material are shown in table 2.
Comparative examples 2 to 6
Comparative examples 2-6 lithium doping was performed on the non-porous silicon oxide particles of the carbon film coated obtained in comparative examples 1-2 in the same manner as in example 2-1. The performance data of the obtained anode active material are shown in table 2.
TABLE 2
According to the results, when the pore diameter of the porous silica particles is less than or equal to 50nm and contains micropores, the structural uniformity of the inside of the particles of the anode active material can be improved, on one hand, the mechanical strength of the anode active material is improved, the bearable compaction density of the pole piece is improved, and on the other hand, the effective utilization rate of the pores in the particles is also improved. Therefore, the energy density and the cycle stability of the anode active material are effectively improved. The excellent effect can be better amplified when the pore diameter of the porous silica particles is further less than or equal to 30nm, even less than or equal to 20nm, and contains micropores. Meanwhile, the carbon film layer on the surface of the porous silica compound particles can effectively reduce side reactions of materials and electrolyte, and improve the stability of the porous silica compound particles in a battery.
Examples 3-1 to 3-6
Examples 3-1 to 3-6 are negative electrode active materials of different relative tap densities obtained by adjusting the addition ratio of the pore-forming precursor based on examples 2-2. Specific performance data are shown in table 3.
TABLE 3 Table 3
According to the results, when the relative tap density is controlled to be more than or equal to 0.75, especially more than or equal to 0.8, the pore volume ratio of the anode active material is relatively balanced, so that the functions of accommodating the volume expansion of the silicon anode and reducing SEI damage can be realized, and the reduction of the mechanical strength of particles and the loss of the volumetric specific energy can be avoided.
Examples 4-1 and 4-2
Examples 4-1 and 4-2 are negative electrode active materials of different carbon film coverage obtained by adjusting parameters of the carbon film coating process based on example 2-1. Specific performance data are shown in table 4.
TABLE 4 Table 4
According to the results, the higher the coverage rate of the carbon film layer on the surface of the porous silica compound particles is, the more direct contact between the porous particles and the electrolyte can be effectively isolated, the adverse effect caused by the larger specific surface area of the porous particles is greatly reduced, the side reaction of materials and the electrolyte is reduced, and the stability of the porous particles in a battery is improved.
It is apparent that the above examples are only examples for clearly illustrating the present application and are not limiting to the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are intended to be within the scope of the present application.
Claims (15)
1. A negative electrode active material for a battery, characterized by comprising negative electrode active material particles; the anode active material particles comprise porous silica compound particles and a carbon film layer, the porous silica compound particles comprise micropores, the pore diameter of the micropores is less than 2nm, and Kong Rong 0.25.25 cm of the porous silica compound particles 3 Preferably less than or equal to 0.2cm 3 And/g, the surface of the porous silica compound particles is partially or completely covered by the carbon film layer.
2. The anode active material according to claim 1, wherein the porous silica compound particles further comprise mesopores having a pore diameter of 2 to 50nm, preferably 2 to 30nm, more preferably 2 to 20nm.
3. The anode active material according to claim 1, wherein the anode active material particles satisfy: d is not less than 0.75, preferably not less than 0.8; wherein d=d1/D2, D is the relative tap density of the anode active material particles, D1 is the tap density of the anode active material particles, and D2 is the tap density when the anode active material particles do not have pores.
4. The anode active material according to claim 1, wherein the anode The specific surface area of the active material is 0.1-15 m 2 Preferably 0.3 to 10m 2 Preferably 0.3 to 6m 2 /g。
5. The anode active material according to claim 1, wherein the anode active material particles further contain a lithium element, and the content of the lithium element is 0.1 to 20wt%, preferably 2 to 18wt%, more preferably 4 to 15wt%.
6. The anode active material according to claim 1, wherein the silicon element content in the porous silicon oxide particles is 30 to 80wt%, preferably 35 to 65wt%, more preferably 40 to 65wt%.
7. The anode active material according to claim 1, wherein the porous silica compound particles have a median particle diameter of 0.2 to 20 μm, preferably 1 to 15 μm, more preferably 3 to 13 μm.
8. The anode active material according to claim 1, wherein the anode active material particles further comprise elemental silicon nanoparticles dispersed within the anode active material particles, the elemental silicon nanoparticles having a median particle diameter of between 0.1 and 35nm, preferably between 0.5 and 20nm, more preferably between 1 and 15nm.
9. The anode active material according to claim 1, wherein the thickness of the carbon film layer is 0.001 to 5 μm, preferably 0.005 to 2 μm, more preferably 0.01 to 1 μm.
10. The anode active material according to claim 1, wherein the carbon film layer accounts for 0.01 to 20wt%, preferably 0.1 to 15wt%, more preferably 1 to 12wt% of the anode active material particles.
11. The negative electrode active material according to claim 1, characterized in that the coverage of the carbon film layer on the surface of the porous silicon oxide particles is not less than 90%, preferably not less than 95%.
12. An electrode comprising the anode active material according to any one of claims 1 to 11.
13. A battery comprising the electrode of claim 12.
14. A method for producing the anode active material according to any one of claims 1 to 11, characterized by comprising the steps of:
directly depositing to obtain the porous silica compound particles; or co-depositing a silica compound and a pore-forming precursor, and then removing the pore-forming precursor to obtain the porous silica compound particles; and
the porous silica compound particles are carbon coated.
15. The method as recited in claim 14, further comprising:
and carrying out lithium doping on the porous silica compound particles coated with the carbon film layer.
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