CN111933919A - Nano silicon powder, silicon-based negative electrode, lithium ion battery containing silicon-based negative electrode and manufacturing method of lithium ion battery - Google Patents

Nano silicon powder, silicon-based negative electrode, lithium ion battery containing silicon-based negative electrode and manufacturing method of lithium ion battery Download PDF

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CN111933919A
CN111933919A CN202010743356.XA CN202010743356A CN111933919A CN 111933919 A CN111933919 A CN 111933919A CN 202010743356 A CN202010743356 A CN 202010743356A CN 111933919 A CN111933919 A CN 111933919A
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silicon
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silicon powder
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CN111933919B (en
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喻维杰
李福生
张锡强
赵常
代学志
詹勇军
杜玮
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Tuomi Chengdu Applied Technology Research Institute Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • H01M4/04—Processes of manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention relates to the technical field of batteries and provides nano silicon powder, a silicon-based negative electrode and a battery comprising the siliconA negative electrode-based lithium ion battery and a method of manufacturing the same. The cycle performance of the silicon-based negative electrode is equivalent to that of a graphite negative electrode, the first discharge efficiency is more than 89%, and the discharge capacity is equivalent to that of a graphite negative electrode>3000 mAh/g. The invention utilizes the in-situ reaction of nano metal oxide, nano silicon particles and a lithium source on the surfaces of the nano silicon particles at high temperature to generate the Li ion conductor2SiO3And a conductive nanometal. The low melting point tin also binds the nano-silicon particles. High-temperature cracking of organic titanium source and/or zirconium source to produce TiO2And/or ZrO2And side reactions between the nano-silicon and the electrolyte are reduced. Cracking an organic aluminum source, and reacting the organic aluminum source with a lithium source to generate a lithium ion conductor LiAlO2. The organic carbon source is cracked into conductive carbon. Such a composite layer system formed on the surface of the nano-silicon particles is essential for the realization of the present invention.

Description

Nano silicon powder, silicon-based negative electrode, lithium ion battery containing silicon-based negative electrode and manufacturing method of lithium ion battery
Technical Field
The invention relates to the technical field of batteries, in particular to nano silicon powder, a silicon-based negative electrode, a lithium ion battery containing the silicon-based negative electrode and a manufacturing method thereof.
Background
The development of human society is severely restricted by the excessive consumption of fossil fuels and the consequent environmental problems in the world today. The construction of a novel society with high efficiency, energy conservation, low carbon and environmental protection becomes the target of the global efforts of all countries. Mankind has formally stepped into the era of electric vehicles in the 21 st century. To improve the endurance mileage of the electric vehicle on the premise of ensuring safety, the energy density of the battery needs to be improved. In 2020, the energy density of the battery cell of the power lithium ion battery for the vehicle reaches 300 Wh/kg. The positive electrode and the negative electrode with high gram capacity are key factors for improving the energy density of the lithium ion battery.
The graphite cathode applied in the traditional commercialization has the advantages of long cycle life, low cost, rich resources and the like, but the theoretical gram capacity of the graphite cathode is only 372mAh/g, and the high energy density requirement of the lithium ion battery cannot be realized. In addition, the lithium intercalation potential of the graphite negative electrode is very close to the deposition potential of metallic lithium, and when the battery is overcharged, lithium dendrite is easily generated on the surface of the electrode, so that the battery is ignited and even explodes, and huge potential safety hazards exist.
Compared with graphite-based negative electrodes, the theoretical gram capacity of the silicon-based negative electrode is the highest among negative electrode materials researched at present, and can reach 4200mAh/g when lithium is completely embedded. In addition, the silicon-based negative electrode has an intercalation/deintercalation lithium potential (0.4V vs. Li/Li)+) Lithium dendrite is difficult to form on the surface of the electrode, the safety performance is good, and the silicon content in the earth crust is high, so that the silicon-based negative electrode can possibly replace a graphite negative electrode to become a new-generation lithium ion battery negative electrode material.
However, silicon-based anodes also suffer from significant drawbacks: during the lithium insertion process, the silicon particles expand by up to 300% in volume, and there is a large volume contraction during the lithium removal. The maximum elastic deformation of the commonly used binder polyvinylidene fluoride (PVDF) is only 9.3%, which is not sufficient to withstand a volume expansion of 300% of the silicon particles. Under the condition, great stress is generated inside the electrode, so that the pole piece is seriously cracked, the active silicon particles are pulverized, and the pulverized silicon particles lose the electric contact with the copper foil of the current collector, thereby causing the severe attenuation of the capacity. Cracking of the silicon particles, an increase in the contact surface with the electrolyte, leads to: 1) a new SEI film is formed, consuming more lithium; 2) the side reactions are exacerbated. These factors result in poor cycling performance of the cell, which has a dramatic decline in cell discharge capacity of 20-50% after several cycles, and also has a low coulombic efficiency (often less than 80%). In addition, the electrical conductivity of silicon material is only 6.7 × 10-4S/cm, the conductivity is poor, which also severely affects the electrochemical performance of the cell. The practical application of the silicon-based negative electrode in the field of lithium ion batteries is greatly hindered by the defects.
At present, the SiO/C composite cathode is practically applied, silicon exists in the form of silicon monoxide, the capacity of SiO is about 1800mAh/g, the capacity of the SiO is reduced after the SiO is compounded with carbon, and the first coulombic efficiency of the SiO/C composite cathode is lower. Therefore, the development of the silicon-based negative electrode with higher capacity and better cycle performance has extremely important practical significance and market value.
The current silicon-based negative electrode is prepared by first nanocrystallizing silicon particles and then performing inorganic ceramic coating and carbon coating. When the grain diameter of the silicon particles is less than 150nm of the critical dimension, the complete spherical morphology can be still maintained after the volume expansion of the lithium intercalation, and the particles can not be crushed and pulverized. And coating the surface of the nano silicon particles with an inorganic layer and then coating a conductive carbon layer. Such inorganic coatings and carbon coatings generally require high temperature processing at temperatures above 750 ℃. The nano silicon particles are easy to grow and agglomerate when treated at high temperature. For example, SiC is coated on the surface of the nano silicon particles in situ, and the heat treatment temperature is 1300 ℃. At such high temperatures, the nano-silicon particles already begin to grow and agglomerate seriously in the industrial production. The capacity of the silicon-based negative electrode prepared by the prior art is still severely attenuated 10 times before circulation, and the cycle performance of the silicon-based negative electrode cannot be compared with that of a graphite negative electrode. Therefore, the severe capacity attenuation of the silicon-based negative electrode is a difficult problem to be solved urgently.
Disclosure of Invention
Technical problem
The invention aims to solve the technical problem of how to improve the first discharge efficiency and the discharge capacity of a silicon-based negative electrode for a lithium ion battery.
A further technical problem to be solved by the present invention is how to make a silicon-based negative electrode for a lithium ion battery exhibit excellent cycle performance while having high first-time discharge efficiency and discharge capacity.
Technical scheme
The technical problem to be solved by the present invention as described above is solved by providing the following three aspects of technical solutions.
In a first aspect: nano silicon powder and its preparing process
A nano silicon powder is in a multilayer structure form of nano silicon core particles/layer A/layer B/layer C, wherein:
the layer A contains Li, at least one of Cu and Ag2SiO3And Sn, the Sn and at least one of Cu and Ag being dispersed at a surface of the silicon nano-core particle, and the Li2SiO3Coating at least part of the surface of the nano silicon core particles;
layer B comprises TiO2And ZrO2And LiAlO and at least one of2And is coated directly and/or indirectly on the surface of the nano-silicon core particles;
layer C comprises carbon and is coated directly and/or indirectly on the surface of the nano-silicon core particle.
The following are used as alternative technical solutions:
a nano silicon powder is in a multilayer structure form of nano silicon core particles/layers A/layers D, wherein:
the layer A contains Li, at least one of Cu and Ag2SiO3And Sn, the Sn and at least one of Cu and Ag being dispersed at a surface of the silicon nano-core particle, and the Li2SiO3Coating at least part of the surface of the nano silicon core particles;
layer D comprises TiO2And ZrO2At least one of, LiAlO2And carbon and coated directly and/or indirectly on the surface of the nano-silicon core particle.
In an exemplary embodiment, the Li is present in the form of nano-silicon core particles2SiO3The weight percentage of (B) is 0.5-4 wt%.
In an exemplary embodiment, the weight percentage of Cu, when present, is 0.2 to 2 wt% based on the weight of the nano-silicon core particles.
In an exemplary embodiment, the weight percentage of Ag, when present, is 0.2-2 wt% based on the weight of the nano-silicon core particles.
In an exemplary embodiment, the weight percentage of Sn is 0.47 to 3 wt% based on the weight of the nano-silicon core particles.
In an exemplary embodiment, the TiO, when present, is based on the weight of the nano-silicon core particle2The weight percentage of (B) is 0.5-8 wt%.
In an exemplary embodiment, the weight of the nano-silicon core particles is measured asWhen present, the ZrO2The weight percentage of (B) is 0.2-5 wt%.
In an exemplary embodiment, the LiAlO is present in the form of a solid, or a mixture thereof2The weight percentage of (B) is 0.5-5 wt%.
In an exemplary embodiment, the weight percentage of carbon is 3 to 15 wt% based on the weight of the nano-silicon core particles.
A method for manufacturing the nano silicon powder, which comprises the following steps:
1) the method comprises the steps of taking nano silicon powder with the particle size of 80-120nm as a raw material, adding nano metal oxide and a first lithium source, and carrying out wet grinding by taking an organic solvent as a dispersing agent, wherein the nano metal oxide is CuO and Ag2At least one of O and SnO2；
2) Vacuum drying the slurry obtained in the step 1), and then sintering the slurry for 2 to 8 hours at the temperature of 450-750 ℃ in the protective atmosphere of nitrogen or argon;
3) cooling in protective atmosphere, and then carrying out vibration dry ball milling;
4) dissolving at least one of an organic titanium source and an organic zirconium source, an organic aluminum source and a second lithium source in an organic solvent, adding the powder subjected to ball milling in the step 3), and stirring and grinding by a wet method;
5) vacuum drying the slurry obtained in the step 4), and then sintering the slurry for 2 to 8 hours at the temperature of 300-500 ℃ in the protective atmosphere of nitrogen or argon;
6) cooling in protective atmosphere, and then carrying out vibration dry ball milling;
7) dissolving an organic carbon source in an organic solvent, adding the powder subjected to ball milling in the step 6), and stirring and grinding by a wet method;
8) vacuum drying the slurry obtained in the step 7), and then sintering the slurry for 2 to 8 hours at the temperature of 500-700 ℃ in the protective atmosphere of nitrogen or argon; and
9) cooling in protective atmosphere, and performing vibration dry ball milling to obtain the nano silicon powder in the form of a multilayer structure of nano silicon core particles/layer A/layer B/layer C.
The following are used as alternative technical solutions:
a method for manufacturing the nano silicon powder, which comprises the following steps:
1) the method comprises the steps of taking nano silicon powder with the particle size of 80-120nm as a raw material, adding nano metal oxide and a first lithium source, and carrying out wet grinding by taking an organic solvent as a dispersing agent, wherein the nano metal oxide is CuO and Ag2At least one of O and SnO2；
2) Vacuum drying the slurry obtained in the step 1), and then sintering the slurry for 2 to 8 hours at the temperature of 450-750 ℃ in the protective atmosphere of nitrogen or argon;
3) cooling in protective atmosphere, and then carrying out vibration dry ball milling;
4) dissolving at least one of an organic titanium source and an organic zirconium source, an organic aluminum source, an organic carbon source and a second lithium source in an organic solvent, adding the powder subjected to ball milling in the step 3), and stirring and grinding by a wet method;
5) vacuum drying the slurry obtained in the step 4), and then sintering the slurry for 2 to 8 hours at the temperature of 500-700 ℃ in the protective atmosphere of nitrogen or argon; and
6) cooling in protective atmosphere, and performing vibration dry ball milling to obtain the nano silicon powder with the multilayer structure of nano silicon core particles/layer A/layer D.
In an exemplary embodiment, 0.25 to 2.5 parts by weight of nano CuO is added in step 1) when added, based on 100 parts by weight of the raw nano silicon powder.
In an exemplary embodiment, 0.2 to 2.1 parts by weight of nano Ag is added in step 1) when added, based on 100 parts by weight of the raw nano silicon powder2O。
In an exemplary embodiment, 0.6 to 3.8 parts by weight of nano SnO is added in step 1) when added, based on 100 parts by weight of raw nano silicon powder2。
In an exemplary embodiment, the first lithium source and the second lithium source are each independently selected from Li2CO3Or LiOH. H2O。
In one exampleIn an exemplary embodiment, 0.42 to 3.33 parts by weight of Li is added in step 1) based on 100 parts by weight of the raw material nano-silicon powder2CO3Or 0.75 to 6 parts by weight of LiOH H2O。
In an exemplary embodiment, the organic titanium source is tetra-n-butyl titanate, tetra-isobutyl titanate, tetra-n-propyl titanate, or di-isopropyl bis (acetylacetonate) titanate.
In an exemplary embodiment, 0.18 to 2.8 molar parts of the organic titanium source is added in step 4) when added, based on 100 molar parts of the raw nano-silicon powder.
In an exemplary embodiment, the organic zirconium source is tetra-n-butyl zirconate, tetra-isobutyl zirconate, or tetra-n-propyl zirconate.
In an exemplary embodiment, 0.045 to 0.57 molar parts of the organozirconium source is added in step 4) when added, based on 100 molar parts of the raw nano-silicon powder.
In an exemplary embodiment, the organic aluminum source is aluminum isopropoxide, aluminum triethoxide, aluminum sec-butoxide, or aluminum tert-butoxide.
In an exemplary embodiment, 0.21 to 2.1 molar parts of the organic aluminum source is added in step 4) based on 100 molar parts of the raw nano-silicon powder.
In an exemplary embodiment, 0.28 to 2.8 parts by weight of Li is added in step 4) based on 100 parts by weight of the raw nano-silicon powder2CO3Or 0.32 to 3.2 parts by weight of LiOH. H2O。
In an exemplary embodiment, the organic carbon source is one or more selected from the group consisting of citric acid, carboxymethyl cellulose, amylose, saccharides (e.g., glucose, sucrose and lactose), resins (e.g., phenol resin, polyacrylic resin, polyester resin, polyamide resin), gelatin, polyaniline, polypyridine, and pitch.
In an exemplary embodiment, 7.3 to 33.3 parts by weight of the organic carbon source is added in step 7) of the above technical scheme or step 4) of the alternative technical scheme based on 100 parts by weight of the raw material nano silicon powder.
In an exemplary embodiment, the organic solvent is absolute ethanol, isopropanol, acetone, N-dimethylacetamide, N-methylpyrrolidone, cyclohexane, chloroform, carbon tetrachloride or silicone oil.
In a second aspect: silicon-based negative electrode and manufacturing method thereof
A silicon-based negative electrode, which adopts the nano-silicon powder of the first aspect as a negative active material.
In an exemplary embodiment, the nano silicon powder is bonded to the negative electrode current collector through carboxyl group-containing polyimide or carboxyl group-containing polyamideimide as a binder.
A method of manufacturing a silicon-based anode as described above, comprising the steps of:
1) preparing anode slurry: adopting the nano silicon powder as a negative active material;
2) coating the negative electrode slurry obtained in the step 1) on a negative electrode current collector and drying.
In an exemplary embodiment, the nano silicon powder of the first aspect as a negative electrode active material, the graphene-carbon nanotube complex NMP slurry as a conductive agent, the solution of the carboxyl group-containing polyamic acid as a binder precursor, the coupling agent, the pore-forming agent, and optionally the electrolyte wetting agent are added to N-methylpyrrolidone or N, N-dimethylacetamide to form a negative electrode slurry in step 1), and the method further comprises a step of treating at a temperature of 280-.
In one exemplary embodiment, the anode active material: conductive agent converted to 100% solids: binder precursor converted to 100% solids 83-90: 1-5: 6-15.
In an exemplary embodiment, the pore-forming agent is added in an amount of 3 to 8 wt% of the anode active material.
In an exemplary embodiment, the coupling agent is added in an amount of 5 to 10 wt% of the binder precursor converted to 100% solids.
In an exemplary embodiment, the electrolyte wetting agent is added in an amount of 2 to 8 wt% of the negative active material.
In an exemplary embodiment, the pore former is naphthalene, Ethylene Carbonate (EC), or biphenyl.
In an exemplary embodiment, the coupling agent is a titanate, zirconate, or aluminate coupling agent.
In an exemplary embodiment, the electrolyte wetting agent is ethylene carbonate EC.
In an exemplary embodiment, the negative current collector is a copper foil or mesh.
In a third aspect: lithium ion battery and method for manufacturing same
A lithium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode is the silicon-based negative electrode of the second aspect.
In an exemplary embodiment, the positive electrode employs high nickel ternary NCM811 or nickel cobalt aluminum NCA as the positive electrode active material.
In one exemplary embodiment, wherein the positive electrode active material is bonded to the positive electrode current collector through carboxyl group-containing polyimides or carboxyl group-containing polyamideimides as a binder.
A method of manufacturing a lithium ion battery as described above, comprising the steps of:
1) preparing a positive electrode; and
2) and assembling the positive electrode, the silicon-based negative electrode of the second aspect, the diaphragm and the electrolyte into the lithium ion battery.
In an exemplary embodiment, the preparing of the positive electrode of step 1) includes:
1-1) preparing positive electrode slurry: adopting high-nickel ternary NCM811 or nickel-cobalt-aluminum NCA as a positive active material;
1-2) coating the positive electrode slurry obtained in the step 1-1) on a positive electrode current collector and drying.
In an exemplary embodiment, the high nickel ternary NCM811 or nickel cobalt aluminum NCA as a positive electrode active material, the graphene-carbon nanotube complex NMP slurry as a conductive agent, the solution of the carboxyl group-containing polyamic acid as a binder precursor, the coupling agent, and optionally the electrolyte wetting agent are added to N-methylpyrrolidone or N, N-dimethylacetamide to form a positive electrode slurry in step 1-1), and the preparation of the positive electrode in step 1) further includes a step of treating in air at a temperature of 280-.
In an exemplary embodiment, the positive electrode active material: conductive agent converted to 100% solids: binder precursor converted to 100% solids 92-95: 3-6: 4-6.
In an exemplary embodiment, the coupling agent is added in an amount of 5 to 10 wt% of the binder precursor converted to 100% solids.
In an exemplary embodiment, the electrolyte wetting agent is added in an amount of 2 to 8 wt% of the positive electrode active material.
In an exemplary embodiment, the coupling agent is a titanate, zirconate, or aluminate coupling agent.
In an exemplary embodiment, the electrolyte wetting agent is ethylene carbonate.
In an exemplary embodiment, the positive electrode current collector is an aluminum foil.
Principle of the invention
The nano silicon has strong reducibility at high temperature, and thermodynamic calculation shows that the nano silicon can easily reduce nano copper oxide, tin oxide, silver oxide and the like at the temperature of 450-750 ℃. The invention utilizes nano metal oxide (copper oxide, silver oxide and stannic oxide) and nano silicon particles to carry out silicothermic reduction reaction at high temperature, firstly, SiO is generated in situ on the surface of the nano silicon core particles2Thin layer and nano metal, SiO generated on the surface of nano silicon core particle2Reaction of the thin layer with an additive lithium source generates Li in situ2SiO3. Since the mobility of lithium ions at high temperatures is much higher than that of Si atoms, Li is generated2SiO3Is located on SiO2Location of thin layers, i.e. in situ generated Li2SiO3Tightly coated on the surface of the nano silicon core particles. The reactions involved are as follows:
Figure RE-GDA0002677021090000091
nano-SnO2+Si＝＝＝＝＝Sn(l)+SiO2Δ G ═ 352.567KJ at 600 ℃
nano-2Ag2O+Si＝＝＝＝＝nano-4Ag+SiO2Δ G ═ 802.245KJ at 600 ℃
SiO2+2LiOH·H2O＝＝＝＝＝Li2SiO3+3H2O
Li2SiO3Is a lithium ion conductor, the generated nano metal (copper or silver) plays a good role in electric conduction, and the metal tin with low melting point plays a role in electric conduction and bonding nano silicon particles.
Then adding organic titanium source and/or organic zirconium source, high-temp. cracking to obtain TiO2And/or ZrO2They are very stable in the electrolyte, and they are directly and/or indirectly coated on the surface of the nano silicon core particles, so that the direct contact between the nano silicon particles and the electrolyte is reduced, and the chance of side reaction between the nano silicon and the electrolyte is reduced. LiAlO generated by cracking the added organic aluminum source and reacting with the lithium source2Is a good lithium ion conductor.
The added organic carbon source is cracked into conductive carbon which is directly and/or indirectly coated on the surface of the nano silicon core particles with high coverage rate. Such a composite layer system formed on the surface of the nano-silicon core particles, both of titanium and/or zirconium oxides resistant to the attack of the electrolyte, and of lithium ion conductors and electron conductors, is crucial for solving the technical problems to be solved by the present invention as described above.
Advantageous effects
The first discharge efficiency of the silicon-based negative electrode for the lithium ion battery is more than 89%, the gram discharge capacity is more than 3000mAh/g, and meanwhile, the cycle performance of the silicon-based negative electrode is equivalent to that of a graphite negative electrode.
Drawings
Fig. 1 shows an SEM photograph of the multi-coated nano-silicon powder of example 1.
Fig. 2 shows an XRD pattern of the multi-coated nano-silicon powder of example 1.
Fig. 3 is a first discharge and charge curve for a silicon vs lithium metal button cell using a silicon-based negative electrode prepared from the multiply-coated nano-silicon powder of example 1.
Fig. 4 is a cycling curve for a silicon vs lithium metal button cell using a silicon-based negative electrode prepared from the multiple coated nano-silicon powder of example 1.
Fig. 5 is the first discharge and charge curves for a silicon vs lithium metal button cell using a silicon-based negative electrode prepared from the multiply-coated nano-silicon powder of example 2.
Fig. 6 is a cycling curve for a silicon vs lithium metal button cell using a silicon-based negative electrode prepared from the multiple coated nano-silicon powder of example 2.
Fig. 7 is a cycle curve for a silicon-based negative electrode vs high-nickel ternary NCM811 positive soft-packed full cell using silicon-based negative electrode vs high-nickel ternary NCM811 prepared from the multiply-coated nano-silicon powder of example 3.
Fig. 8 is a cycle curve for a flexible-packaged full-cell silicon-based negative electrode vs ni — co-al NCA positive electrode prepared from the multiply-coated nano-silicon powder of example 4.
Fig. 9 is an XRD pattern of the nano silicon powder of verification experiment 1.
Fig. 10 is an XRD pattern of the nano silicon powder of verification experiment 2.
Detailed Description
Some specific embodiments of the nano-silicon powder, the silicon-based negative electrode, the lithium ion battery including the silicon-based negative electrode, and the method of manufacturing the same according to the present invention are described in detail below in order to more fully illustrate some and other features and advantages of the present invention. It should be understood that these embodiments are merely illustrative, and the scope of the present invention is not limited thereto.
Examples 1 to 21: nano silicon powder and its preparationManufacturing method
Example 1:
this example prepares a nano-silicon powder, which is in the form of a multi-layer structure of nano-silicon core particles/layer a/layer D, wherein:
layer A contains Cu and Li2SiO3And Sn, wherein the Cu, Li are based on the weight of the nano-silicon core particles2SiO3And Sn in a weight percentage of 1%, 1.5% and 1%, respectively, the Cu and the Sn being dispersed at the surface of the silicon nano-core particle, and the Li2SiO3Coating on at least part of the surface of the nano silicon core particles;
layer D comprises TiO2、ZrO2、LiAlO2And carbon and coated directly and/or indirectly on the surface of the nano-silicon core particle, wherein the TiO is based on the weight of the nano-silicon core particle2、ZrO2、 LiAlO2And 3.1%, 2.1%, 2.2%, 10.5% by weight of carbon, respectively.
In the embodiment, nano silicon powder prepared by silane gas phase cracking is used as a raw material, and the particle size of primary particles of the silicon powder is 80-120nm through the observation of a scanning electron microscope. The laser particle size analyzer test D10 ═ 0.11 μm, D50 ═ 0.32 μm, and D90 ═ 0.52 μm.
The preparation method of the nano silicon powder comprises the following steps:
1) 6kg of nano silicon powder raw material, 80g of nano copper oxide, 76g of nano tin dioxide and 85g of LiOH.H2O is added into 5kg of cyclohexane, and wet grinding is carried out for 30 minutes by using a phi 3 zirconia grinding ball;
2) drying the slurry obtained in the step 1) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 650 ℃ for 8 hours;
3) cooling in protective atmosphere, and then carrying out vibration dry ball milling for 1 hour;
4) in 5kg of cyclohexane were dissolved 0.8kg of tetra-n-butyl titanate, 0.4kg of tetra-n-butyl zirconate, 0.4kg of aluminum isopropoxide, 0.6kg of asphalt block, 0.8kg of carboxymethyl cellulose CMC and 83g of LiOH. H2O, addition ofWet grinding all the powder subjected to ball milling in the step 3) for 30 minutes by using phi 3 zirconia grinding balls;
5) drying the slurry obtained in the step 4) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 650 ℃ for 8 hours; and
6) cooling the sintered product obtained in the step 5) in a protective atmosphere, and then carrying out vibration dry ball milling for 1 hour.
The scanning electron micrograph of the obtained nano-silicon powder is shown in FIG. 1. The primary particle size of the obtained nano silicon powder is maintained below 120nm, and the nano silicon powder is agglomerated into micron-sized particles, wherein D10 is 0.55 mu m, D50 is 2.5 mu m, and D90 is 6.2 mu m.
Fig. 2 shows an XRD pattern of the nano silicon powder prepared in example 1.
Due to the limitation of sensitivity of XRD test, the trace amount of Li in the nano-silicon powder prepared in example 12SiO3、LiAlO2、TiO2、ZrO2And are difficult to detect. For this purpose, the following validation experiments were added.
Verification experiment 1
1) 30g of nano silicon powder raw material, 10g of nano copper oxide, 15g of nano tin dioxide and 13.8g of LiOH. H2O is added into 85g N-methyl pyrrolidone, and wet grinding is carried out for 30 minutes by using phi 3 zirconia grinding balls;
2) drying the slurry obtained in the step 1) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 680 ℃ for 2 hours;
3) cooling in protective atmosphere, and then carrying out vibration dry ball milling for 1 hour;
the XRD pattern as shown in fig. 9 shows that: the main phase is Si, and the secondary phase is Sn, Cu, Li2SiO3And Cu6Sn5. CuO and SnO2Is completely reduced. Due to CuO and SnO2Is added in a large amount, and besides Sn and Cu metals, a small amount of Cu is formed6Sn5An alloy phase. It is believed that the Cu and Sn particles formed are only near the contact, whenAn alloy phase can be formed at high temperature. Thus, in example 1, SnO2And CuO is added in a small amount, and a small amount of generated Cu and Sn particles are completely separated by nano-silicon particles, so that Cu may not be formed6Sn5An alloy phase.
Verification experiment 2
1) In 100g of cyclohexane and 100g N-methylpyrrolidone were dissolved 22.2g of tetra-n-butyl titanate, 11.8g of tetra-n-butyl zirconate, 28.5g of aluminum isopropoxide and 5.9g of LiOH. H2O, adding 50g of nano silicon powder raw material, and carrying out wet grinding for 30 minutes by using a phi 3 zirconia grinding ball;
2) drying the slurry obtained in the step 1) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 500 ℃ for 2 hours; and
3) cooling the sintered product obtained in the step 2) in a protective atmosphere, and then carrying out vibration dry ball milling for 1 hour.
The XRD pattern as shown in fig. 10 shows that: the main phase being Si and the secondary phase having LiAlO2、TiO2And ZrO2. This validation experiment demonstrates the formation of LiAlO from the titanium, zirconium, aluminum and lithium sources described in example 1 under the experimental conditions described above2、TiO2、ZrO2。
Example 2:
this example prepares a nano-silicon powder, which is in the form of a multi-layer structure of nano-silicon core particles/layer a/layer B/layer C, wherein:
layer A contains Cu and Li2SiO3And Sn, wherein the Cu, LiSiO are based on the weight of the nano silicon core particles3And Sn in a weight percentage of 1%, 1.5% and 1%, respectively, the Cu and the Sn being dispersed at the surface of the silicon nano-core particle, and the Li2SiO3Coating at least part of the surface of the nano silicon core particles;
layer B comprises TiO2、ZrO2And LiAlO2And is coated directly and/or indirectly on the surface of the nano-silicon core particle, wherein the TiO is based on the weight of the nano-silicon core particle2、ZrO2And LiAlO2The weight percentages of the components are respectively 2.9%, 2% and 2%;
layer C comprises carbon and is coated directly and/or indirectly on the surface of the nano-silicon core particle, wherein the weight percentage of carbon is 8.4% by weight of the nano-silicon core particle.
In this embodiment, nano-silicon powder prepared by gas-phase cracking of silane is used as a raw material, and the particle size of the primary particle of the silicon powder is about 120nm as observed by a scanning electron microscope. The laser particle size analyzer test D10 ═ 0.10 μm, D50 ═ 0.31 μm, and D90 ═ 0.54 μm.
The preparation method of the nano silicon powder comprises the following steps:
1) 8kg of nano silicon powder raw material, 107g of nano copper oxide, 102g of nano tin dioxide and 114g of LiOH. H2O is added into 10kg of N, N-dimethylacetamide, and wet grinding is carried out for 30 minutes by using phi 3 zirconia grinding balls;
2) drying the slurry obtained in the step 1) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 450 ℃ for 8 hours;
3) cooling in protective atmosphere, and then carrying out vibration dry ball milling for 1 hour;
4) in 15kg of cyclohexane were dissolved 1kg of tetra-n-butyl titanate, 0.5kg of tetra-n-butyl zirconate, 0.5kg of aluminum isopropoxide, and 104g of LiOH. H2O, adding all the powder subjected to ball milling in the step 3), and performing wet grinding for 30 minutes by using phi 3 zirconia grinding balls;
5) drying the slurry obtained in the step 4) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 300 ℃ for 2 hours; and
6) cooling the sintered product obtained in the step 5) in a protective atmosphere, and then carrying out vibration dry ball milling for 1 hour.
7) Dissolving 0.8kg of asphalt blocks and 0.5kg of carboxymethyl cellulose CMC in 6kg of cyclohexane, adding all the powder subjected to ball milling in the step 6), and performing wet grinding for 30 minutes by using phi 3 zirconia grinding balls;
8) drying the slurry obtained in the step 7) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 750 ℃ for 2 hours; and
9) cooling the sintered product obtained in the step 8) in a protective atmosphere, and then carrying out vibration dry ball milling for 1 hour.
The primary particle size of the obtained nano silicon powder is maintained at about 120nm, and the nano silicon powder is agglomerated into micron-sized particles, wherein D10 is 0.6 mu m, D50 is 2.5 mu m, and D90 is 6.5 mu m.
Example 3:
this example prepares a nano-silicon powder, which is in the form of a multi-layer structure of nano-silicon core particles/layer a/layer D, wherein:
layer A contains Cu, Ag, Li2SiO3And Sn, wherein the Cu, Ag, Li are based on the weight of the nano-silicon core particles2SiO3And Sn in a weight percentage of 1%, 0.78%, 1.7% and 1%, respectively, the Cu and Ag and the Sn being dispersed at the surface of the silicon nano-core particle, and the Li2SiO3Coating at least part of the surface of the nano silicon core particles;
layer D comprises TiO2、ZrO2、LiAlO2And carbon and coated directly and/or indirectly on the surface of the nano-silicon core particle, wherein the TiO is based on the weight of the nano-silicon core particle2、 ZrO2、LiAlO2And 3.1%, 2.1%, 2.2%, 10.5% by weight of carbon, respectively.
In the embodiment, nano silicon powder prepared by silane gas phase cracking is used as a raw material, and the particle size of primary particles of the silicon powder is 80-120nm through the observation of a scanning electron microscope. The laser particle size analyzer test D10 ═ 0.10 μm, D50 ═ 0.32 μm, and D90 ═ 0.51 μm.
The preparation method of the nano silicon powder comprises the following steps:
1) 6kg of nano silicon powder raw material, 80g of nano copper oxide, 50g of nano silver oxide, 76g of nano tin dioxide and 95g of LiOH.H2O is added into 10kg of cyclohexane, and wet grinding is carried out for 30 minutes by using a phi 3 zirconia grinding ball;
2) drying the slurry obtained in the step 1) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 600 ℃ for 8 hours;
3) cooling in protective atmosphere, and then carrying out vibration dry ball milling for 1 hour;
4) in 5kg of cyclohexane and 10kg of N, N-dimethylacetamide were dissolved 0.8kg of tetra-N-butyl titanate, 0.4kg of tetra-N-butyl zirconate, 0.4kg of aluminum isopropoxide, 0.6kg of asphalt block, 0.8kg of carboxymethyl cellulose CMC and 83g of LiOH H2O, adding all the powder subjected to ball milling in the step 3), and performing wet grinding for 30 minutes by using phi 3 zirconia grinding balls;
5) drying the slurry obtained in the step 4) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 700 ℃ for 2 hours; and
6) cooling the sintered product obtained in the step 5) in a protective atmosphere, and then carrying out vibration dry ball milling for 1 hour.
The primary particle size of the obtained nano silicon powder is maintained below 120nm, and the nano silicon powder is agglomerated into micron-sized particles, wherein D10 is 0.7 mu m, D50 is 2.6 mu m, and D90 is 6.8 mu m.
Example 4:
this example prepares a nano-silicon powder, which is in the form of a multi-layer structure of nano-silicon core particles/layer a/layer D, wherein:
layer A contains Cu, Ag, Li2SiO3And Sn, wherein the Cu, Ag, Li are based on the weight of the nano-silicon core particles2SiO3And Sn in a weight percentage of 1%, 0.77%, 1.7% and 1%, respectively, the Cu and Ag and the Sn being dispersed at the surface of the silicon nano-core particle, and the Li2SiO3Coating at least part of the surface of the nano silicon core particles;
layer D comprises TiO2、ZrO2、LiAlO2And carbon and coated directly and/or indirectly on the surface of the nano-silicon core particle, wherein the TiO is based on the weight of the nano-silicon core particle2、ZrO2、LiAlO2And 2.3%, 1.6% and 8.4% by weight of carbon, respectively.
In the embodiment, the nano silicon powder obtained by grinding polycrystalline silicon powder by a nano sand mill is used as a raw material, and the particle size of primary particles of the silicon powder is about 120nm through the observation of a scanning electron microscope. Laser granulometer test D10 ═ 0.11 μm, D50 ═ 0.38 μm, and D90 ═ 0.75 μm.
The preparation method of the nano silicon powder comprises the following steps:
1) 8kg of nano silicon powder raw material, 107g of nano copper oxide, 66g of nano silver oxide, 102g of nano tin dioxide and 130g of LiOH. H2O is added into 10kg of N, N-dimethylacetamide, and wet grinding is carried out for 30 minutes by using phi 3 zirconia grinding balls;
2) drying the slurry obtained in the step 1) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 750 ℃ for 2 hours;
3) cooling in protective atmosphere, and then carrying out vibration dry ball milling for 1 hour;
4) in 5kg of cyclohexane and 10kg of N, N-dimethylacetamide were dissolved 0.8kg of tetra-N-butyl titanate, 0.4kg of tetra-N-butyl zirconate, 0.4kg of aluminum isopropoxide, 0.8kg of asphalt block, 0.5kg of carboxymethyl cellulose CMC and 83g of LiOH H2O, adding all the powder subjected to ball milling in the step 3), and performing wet grinding for 30 minutes by using phi 3 zirconia grinding balls;
5) drying the slurry obtained in the step 4) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 700 ℃ for 2 hours; and
6) cooling the sintered product obtained in the step 5) in a protective atmosphere, and then carrying out vibration dry ball milling for 1 hour.
The primary particle size of the obtained nano silicon powder is maintained at about 120nm, and the nano silicon powder is agglomerated into micron-sized particles, wherein D10 is 0.9 mu m, D50 is 2.5 mu m, and D90 is 6.8 mu m.
Example 5:
this example prepares a nano-silicon powder, which is in the form of a multi-layer structure of nano-silicon core particles/layer a/layer B/layer C, wherein:
layer A contains Cu, Ag, Li2SiO3And Sn, wherein the Cu, Ag, Li are based on the weight of the nano-silicon core particles2SiO3And Sn in an amount of 0.5%, 0.4%, 0.8% and 0.5% by weight, respectively, the Cu and Ag and the Sn being dispersed at the surface of the nano-silicon core particle, and the Li2SiO3Coating at least part of the surface of the nano silicon core particles;
layer B comprises TiO2And LiAlO2And is coated directly and/or indirectly on the surface of the nano-silicon core particle, wherein the TiO is based on the weight of the nano-silicon core particle2And LiAlO2The weight percentages of the components are respectively 1.5 percent and 1 percent;
layer C comprises carbon and is coated directly and/or indirectly on the surface of the nano-silicon core particle, wherein the weight percentage of carbon is 5.7% by weight of the nano-silicon core particle.
In the embodiment, nano silicon powder prepared by silane gas phase cracking is used as a raw material, and the particle size of primary particles of the silicon powder is 80-120nm through the observation of a scanning electron microscope. The laser particle size analyzer test was 0.12 μm for D10, 0.35 μm for D50, and 0.55 μm for D90.
The preparation method of the nano silicon powder comprises the following steps:
1) 6kg of nano silicon powder raw material, 40g of nano copper oxide, 25g of nano silver oxide, 38g of nano tin dioxide and 46g of LiOH. H2O is added into 10kg of cyclohexane, and wet grinding is carried out for 30 minutes by using a phi 3 zirconia grinding ball;
2) drying the slurry obtained in the step 1) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 450 ℃ for 8 hours;
3) cooling in protective atmosphere, and then carrying out vibration dry ball milling for 1 hour;
4) in 5kg of cyclohexane and 2kg of N, N-dimethylacetamide were dissolved 0.4kg of tetra-N-butyl titanate, 0.2kg of aluminum isopropoxide, and 42g of LiOH. H2O, adding all the ball-milled materials obtained in the step 3)Wet grinding the powder for 30 minutes by using a phi 3 zirconia grinding ball;
5) drying the slurry obtained in the step 4) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 300 ℃ for 8 hours; and
6) cooling the sintered product obtained in the step 5) in a protective atmosphere, and then carrying out vibration dry ball milling for 1 hour.
7) Dissolving 0.3kg of asphalt and 0.5kg of carboxymethyl cellulose CMC in 5kg of cyclohexane, adding all the powder subjected to ball milling in the step 6), and performing wet grinding for 30 minutes by using a phi 3 zirconia grinding ball;
8) drying the slurry obtained in the step 7) in a vacuum rotary dryer at 80 ℃ in vacuum, and then sintering the slurry in a pushed slab kiln in a high-purity nitrogen (99.999%) protective atmosphere at 750 ℃ for 2 hours; and
9) cooling the sintered product obtained in the step 8) in a protective atmosphere, and then carrying out vibration dry ball milling for 1 hour.
The primary particle size of the obtained nano silicon powder is maintained below 120nm, and the nano silicon powder is agglomerated into micron-sized particles, wherein D10 is 0.8 mu m, D50 is 2.6 mu m, and D90 is 6.5 mu m.
Examples 6 to 21:
examples 6-21 are similar to examples 1-5, except for the weight percentages of the components in the nano-sized silicon powder and the associated process parameters in the manufacturing process. For convenience, the text description of examples 6 to 21 will not be repeated. Tables 1-2 and 3-4 respectively list the compositions of the nano-silicon powders and the process parameters in the preparation methods of examples 6-21.
Table 1: weight percent composition of the silicon nanopowders of examples 6-13 (silicon nanopowder/layer A/layer B/layer C, based on 100 parts by weight of silicon nanopowder)
Figure RE-GDA0002677021090000181
Table 2: weight percent composition of the silicon nanopowders of examples 14-21 (silicon nanopowder/layer A/layer D, based on 100 parts by weight of silicon nanopowder)
Figure RE-GDA0002677021090000182
Figure RE-GDA0002677021090000191
TABLE 3 Process parameters of the preparation methods of nano-silicon powders of examples 6 to 13 (note: the portions not mentioned are similar to examples 1 to 5)
Figure RE-GDA0002677021090000192
Figure RE-GDA0002677021090000201
TABLE 4 Process parameters of the preparation methods of nano-silicon powders of examples 14 to 21 (the parts not mentioned are similar to those of examples 1 to 5)
Figure RE-GDA0002677021090000202
Figure RE-GDA0002677021090000211
Figure RE-GDA0002677021090000221
The primary particle size of the nano-silicon powder prepared in examples 6 to 21 was maintained at 80 to 120nm, and the nano-silicon powder was agglomerated into micron-sized particles, D10 ═ 0.5 to 1.1 μm, D50 ═ 2.5 to 3.5 μm, and D90 ═ 6.0 to 12 μm.
Examples 22 to 42: silicon-based negative electrode and manufacturing method thereof
Example 22:
this example prepared a silicon-based negative electrode using the nano-silicon powder of example 1 as a negative electrode active material, the nano-silicon powder being bonded to a negative electrode current collector through carboxyl group-containing polyimides as a binder.
The preparation method of the silicon-based anode of the embodiment comprises the following steps:
1) 15g of the nano silicon-based powder obtained from example 1, 28g of graphene-carbon nanotube complex NMP slurry (solid content 5.6 wt%), 13g of a solution of a carboxyl group-containing polyamic acid binder precursor (solid content 15 wt%), 0.1g of tetra-n-butyl zirconate, 20g of a 5 wt% naphthalene/NMP solution, and 1g of an electrolyte wetting agent, ethylene carbonate EC, were dispersed in 40g N-methylpyrrolidone and stirred to form a slurry, wherein the carboxyl group-containing polyamic acid binder precursor has the following structural formula:
Figure RE-GDA0002677021090000222
2) coating the slurry obtained in step 1) on a copper foil to form a coating layer with a thickness of 200 μm and drying at 80 ℃ for 12 hours in a vacuum oven; and
3) imidizing at 300 ℃ for 30 minutes in high-purity nitrogen gas to obtain the silicon-based negative electrode.
The pole piece of the silicon-based negative electrode is well bonded, and no cracking phenomenon exists after drying. And (5) accurately weighing the pole piece after cooling. In a glove box protected by high-purity argon, metal lithium is used as a counter electrode, a diaphragm is Celgard2400, and electrolyte is 1M LiPF6/EC + DEC, assembling CR2032 button half cells.
The voltage range of the button type half cell test is 0.02-1.5V. Referring to FIGS. 3 and 4, the first coulombic efficiency was 89.28% and the first discharge gram capacity was 3228 mAh/g. The charging capacity did not decay any more for the first 15 cycles at 0.1C.
Example 23:
this example prepares a silicon-based negative electrode using the nano-silicon powder of example 2 as a negative active material. The nano silicon powder is bonded with a negative current collector through carboxyl-containing polyamide imide serving as a bonding agent.
The preparation method of the silicon-based anode of the embodiment comprises the following steps:
1) 15g of the nano silicon-based powder obtained in example 2, 25g of graphene-carbon nanotube complex NMP slurry (solid content 6 wt%), 13g of a solution of a carboxyl-containing polyamic acid binder precursor (solid content 15 wt%), 0.1g of tetra-n-butyl titanate, 20g of a 5 wt% biphenyl/NMP solution, and 1g of ethylene carbonate EC were dispersed in 40g N-methylpyrrolidone and stirred to form a slurry, wherein the carboxyl-containing polyamic acid binder precursor has the following structural formula:
Figure RE-GDA0002677021090000231
2) coating the slurry obtained in step 1) on a copper foil to form a coating layer with a thickness of 200 μm and drying at 80 ℃ for 12 hours in a vacuum oven; and
3) imidizing at 320 ℃ for 20 minutes in high-purity nitrogen gas to obtain the silicon-based negative electrode.
The pole piece of the silicon-based negative electrode is well bonded, and no cracking phenomenon exists after drying. And (5) accurately weighing the pole piece after cooling. Then in a glove box protected by high-purity argon, metal lithium is taken as a counter electrode, a diaphragm is Celgard2400, and electrolyte is 1M LiPF6/EC + DEC, assembling CR2032 button half cells.
The voltage range of the button cell test is 0.02-1.5V. Referring to FIGS. 5 and 6, the first coulombic efficiency was 89.93%, and the first discharge gram capacity was 3238 mAh/g. The charging capacity did not decay any more for the first 15 cycles at 0.1C.
Example 24:
this example prepares a silicon-based negative electrode using the nano-silicon powder of example 3 as a negative active material. The nano silicon powder is bonded with a negative current collector through carboxyl-containing polyimide serving as a bonding agent.
The preparation method of the silicon-based anode of the embodiment comprises the following steps:
1) 3kg of the nano silicon-based powder obtained from example 3, 5.6kg of graphene-carbon nanotube complex NMP slurry (solid content 5.6 wt%), 2.6kg of a solution of a carboxyl group-containing polyamic acid binder precursor (solid content 15 wt%), 30g of tetra-N-butyl titanate, 2kg of a 5 wt% naphthalene/NMP solution, and 60g of Ethylene Carbonate (EC) were dispersed in 5kg of N-methylpyrrolidone to form a slurry, wherein the carboxyl group-containing polyamic acid binder precursor has the following structural formula:
Figure RE-GDA0002677021090000241
2) coating the slurry obtained in the step 1) on a copper foil to form a coating with the thickness of 50 microns, and drying the coating in a vacuum oven at 80 ℃ for 12 hours, wherein the thickness of the coating on one side of the dried silicon-based negative pole piece is about 20 microns due to low solid content of the slurry; and
3) imidizing for 180 minutes at the temperature of 280 ℃ in high-purity nitrogen gas to obtain the silicon-based negative electrode.
The pole piece of the silicon-based negative electrode is well bonded, and no cracking phenomenon exists after drying. And (5) accurately weighing the cooled pole piece. Then in a glove box protected by high-purity argon, metal lithium is taken as a counter electrode, a diaphragm is Celgard2400, and electrolyte is 1M LiPF6/EC + DEC, assembling CR2032 button half cells.
The voltage range of the button cell test is 0.02-1.5V, the first coulombic efficiency is 89.5%, and the first discharge gram capacity is 3130 mAh/g. The charging capacity did not decay any more for the first 15 cycles at 0.1C.
Example 25:
this example prepares a silicon-based negative electrode using the nano-silicon powder of example 4 as a negative active material. The nano silicon powder is bonded with a negative current collector through carboxyl-containing polyamide imide serving as a bonding agent.
The preparation method of the silicon-based anode of the embodiment comprises the following steps:
1) 3kg of the nano silicon-based powder obtained in example 4, 5.6kg of graphene-carbon nanotube composite NMP slurry (solid content 5.6 wt%), 2.6kg of a solution of a carboxyl-containing polyamic acid binder precursor (solid content 15 wt%), 30g of an aluminate coupling agent (distearoyl oxy isopropoxy aluminate), 2kg of a 5 wt% naphthalene/NMP solution, and 60g of Ethylene Carbonate (EC) were dispersed in 6kg of N, N-dimethylacetamide to form a slurry, wherein the carboxyl-containing polyamic acid binder precursor has the following structural formula:
Figure RE-GDA0002677021090000251
2) coating the slurry obtained in the step 1) on a copper foil to form a coating with the thickness of 80 microns, and drying the coating in a vacuum oven at 80 ℃ for 12 hours, wherein the thickness of the coating on one side of the dried silicon-based negative pole piece is about 38 microns due to low solid content of the slurry; and
3) imidizing at 320 ℃ for 20 minutes in high-purity nitrogen gas to obtain the silicon-based negative electrode.
The pole piece of the silicon-based negative electrode is well bonded, and no cracking phenomenon exists after drying. And (5) accurately weighing the pole piece after cooling. Then in a glove box protected by high-purity argon, metal lithium is taken as a counter electrode, a diaphragm is Celgard2400, and electrolyte is 1M LiPF6/EC + DEC, assembling CR2032 button half cells.
The voltage range of the button cell test is 0.02-1.5V, the first coulombic efficiency is 90.2%, and the first discharge gram capacity is 3180 mAh/g. The charging capacity did not decay any more for the first 15 cycles at 0.1C.
Examples 26 to 42:
examples 26-42 are similar to examples 22-25 except for the individual starting materials in the silicon-based anode and their weights and associated process parameters in the preparation process. For convenience, the text description of examples 26 to 42 will not be repeated. Tables 5 and 6 set forth the respective raw materials and their weights and process parameters in the preparation methods for the silicon-based anodes of examples 26-42, respectively.
Table 5: raw materials for silicon-based negative electrodes of examples 26 to 42 and weights thereof (portions not mentioned are similar to examples 22 to 25)
Figure RE-GDA0002677021090000261
Figure RE-GDA0002677021090000271
Table 6 process parameters of the preparation method of silicon-based negative electrodes of examples 26 to 42 (parts not mentioned are similar to examples 22 to 25)
Figure RE-GDA0002677021090000272
Figure RE-GDA0002677021090000281
The pole pieces of the silicon-based negative electrodes of examples 26 to 42 were very well bonded and did not crack after drying. And (5) accurately weighing the pole piece after cooling. Then in a glove box protected by high-purity argon, metal lithium is taken as a counter electrode, a diaphragm is Celgard2400, and electrolyte is 1M LiPF6/EC + DEC, assembling CR2032 button half cells.
The voltage range of the button cell test is 0.02-1.5V, the first coulombic efficiency is 88.2-90.5%, and the first discharge gram capacity is 3020-3290 mAh/g. The charging capacity did not decay any more for the first 15 cycles at 0.1C.
Examples 43 to 61 lithium ion batteries and methods for producing the same
Example 43:
this example prepared a lithium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode was the silicon-based negative electrode from example 24.
The preparation method of the lithium ion battery of the embodiment comprises the following steps:
1) 3kg of high-nickel ternary NCM811 cathode active material powder, 2kg of graphene-carbon nanotube compound NMP slurry (solid content 5.6 wt%), 1kg of solution of carboxyl-containing polyamide acid binder precursor (solid content 15 wt%), 10g of tetra-N-butyl titanate and 90 g of Ethylene Carbonate (EC) are dispersed in 4kg of N-methyl pyrrolidone to form slurry with the viscosity of about 9000cP, wherein the structural formula of the carboxyl-containing polyamide acid binder precursor is as follows:
Figure RE-GDA0002677021090000291
2) coating the slurry obtained in the step 1) on an aluminum foil and drying in vacuum, wherein the thickness of the coating is 400 microns, and the thickness of the single-side coating after drying is about 280 microns;
3) imidizing for half an hour at 290 ℃ in the air to obtain a positive plate; and
4) the positive plate, the silicon-based negative plate of example 24 and a separator Celgard2400 were laminated with a negative/positive capacity ratio N/P of about 1.1, and then the positive and negative tabs were welded, an aluminum plastic bag was placed, sealed, and an electrolyte (1M LiPF) was injected6/EC + DEC), sealing, laying aside, pre-charging to 3.2V, and sealing.
And charging the lithium ion battery to 4.2V, and grading the capacity. The cycling performance of the cells was tested at a voltage range of 2.75-4.2V.
The result shows that the soft package lithium ion battery has the performance completely similar to that of a graphite cathode: the first coulombic efficiency was 89.2%, 0.5C charge-discharge cycle, and the capacity remained 95.66% for the first 200 cycles (see fig. 7).
Example 44:
this example prepared a lithium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode was the silicon-based negative electrode from example 25.
The preparation method of the lithium ion battery of the embodiment comprises the following steps:
1) 3kg of nickel-cobalt-aluminum (nickel-cobalt-aluminum) NCA positive electrode active material powder, 2kg of graphene-carbon nanotube compound NMP slurry (solid content 5.6 wt%), 1kg of a solution of a carboxyl-containing polyamic acid binder precursor (solid content 15 wt%), 7.5g of tetra-N-butyl zirconate and 60g of Ethylene Carbonate (EC) were dispersed in 4kg of N-methylpyrrolidone to form a slurry having a viscosity of about 9000cP, wherein the structural formula of the carboxyl-containing polyamic acid binder precursor was as follows:
Figure RE-GDA0002677021090000301
2) coating the slurry obtained in the step 1) on an aluminum foil and drying in vacuum, wherein the thickness of the coating is 400 mu m. The thickness of the single-sided coating after drying is about 280 mu m;
3) imidizing for half an hour at the temperature of 280 ℃ in the air to obtain a positive plate; and
4) the positive plate, the silicon-based negative plate of example 25 and the separator Celgard2400 were laminated with a negative/positive capacity ratio N/P of about 1.1, and then the positive and negative tabs were welded, an aluminum plastic bag was placed, sealed, and an electrolyte (1M LiPF) was injected6/EC + DEC), sealing, laying aside, pre-charging to 3.2V, and sealing.
And charging the lithium ion battery to 4.2V, and grading the capacity. The cycling performance of the cells was tested at a voltage range of 2.75-4.2V.
The result shows that the soft package lithium ion battery has the performance completely similar to that of a graphite cathode: the first coulombic efficiency was 89.1%, the charge-discharge cycle at 0.5C, and the capacity remained 94.77% for the first 160 cycles (see fig. 8).
Examples 45 to 61:
examples 45-61 are similar to examples 43-44 except that the lithium ion battery was prepared with the respective starting materials and their weights and associated process parameters. For convenience, the text description of examples 45 to 61 will not be repeated. Tables 7 and 8 set forth the respective starting materials and their weights and process parameters in the preparation methods for the lithium ion batteries of examples 45-61, respectively.
Table 7: starting materials for lithium ion batteries of examples 45 to 61 and weights thereof (portions not mentioned are similar to examples 43 to 44)
Figure RE-GDA0002677021090000302
Figure RE-GDA0002677021090000311
Figure RE-GDA0002677021090000321
TABLE 8 Process parameters for the preparation of the lithium-ion batteries of examples 45 to 61 (the parts not mentioned are similar to examples 43 to 44)
Figure RE-GDA0002677021090000322
And charging the lithium ion battery to 4.2V, and grading the capacity. The cycling performance of the cells was tested at a voltage range of 2.75-4.2V.
The results show that the soft-packed lithium ion batteries of examples 45-61 exhibit properties completely similar to graphite-based anodes: the first coulombic efficiency is 87.5-89.5%, the charge-discharge circulation is 0.5C, and the capacity of the previous 160 circulation is kept 88.5-96.0%.
Comparative examples 1 to 3:
comparative example 1:
this comparative example prepared a nano-silicon powder similar to that of example 1 except that layer D did not contain LiAlO2。
The preparation method of the nano silicon powder of this comparative example is similar to that of example 1 except that aluminum isopropoxide and LiOH. H are not added in step 4)2O。
The primary particle size of the obtained nano silicon powder is maintained at 120nm, and the nano silicon powder is agglomerated into micron-sized particles, wherein D10 is 0.55 mu m, D50 is 2.45 mu m, and D90 is 6.24 mu m.
Comparative example 2:
this comparative example prepared a silicon-based anode, which was similar to example 22 except that the nano-silicon powder of comparative example 1 was used as an anode active material.
The silicon-based anode of this comparative example was prepared substantially in the same manner as in example 22.
The pole piece of the silicon-based negative electrode is well bonded, and no cracking phenomenon exists after drying. And (5) accurately weighing the pole piece after cooling. In a glove box protected by high-purity argon, metal lithium is used as a counter electrode, a diaphragm is Celgard2400, and electrolyte is 1M LiPF6/EC + DEC, assembling CR2032 button half cells.
The voltage range of the button type half cell test is 0.02-1.5V. The first coulombic efficiency was 86.5%, and the first discharge gram capacity was 2980 mAh/g. The charging capacity of the first 15 cycles of 0.1C has 210mAh/g of decay.
Comparative example 3:
this comparative example prepared a lithium ion battery similar to example 43 except that the negative electrode was a silicon-based negative electrode from comparative example 2.
The lithium ion battery of this comparative example was prepared in substantially the same manner as in example 43.
And charging the lithium ion battery to 4.2V, and grading the capacity. The cycling performance of the cells was tested at a voltage range of 2.75-4.2V.
The result shows that the first coulombic efficiency of the flexible package lithium ion battery is 87.5 percent, the charge-discharge cycle is 0.5C, and the previous cycle capacity of 160 times is kept 81.1 percent.
It should be noted that although one of the carboxyl group-containing polyamide-based binder precursors having a specific structural formula is used in the above examples, it should be understood that any suitable other binder precursor or binder known to those skilled in the art may be used.
All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.
Any feature disclosed in this specification may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. Unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which these exemplary embodiments belong. The terminology used in the description herein is for the purpose of describing exemplary embodiments only and is not intended to be limiting of exemplary embodiments. Accordingly, the overall inventive concept is not intended to be limited to the specific embodiments described herein. Although preferred methods and materials are described herein, other methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention.
Unless otherwise indicated, all numbers expressing quantities of ingredients, chemical and molecular properties, reaction conditions, and so forth, used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the exemplary embodiments herein. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the number of equivalents, each numerical parameter should at least be construed in light of the number of reported significant digits and ordinary rounding approaches.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the exemplary embodiments are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Every numerical range given throughout this specification and claims will include every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein. Further, any numerical values reported in the examples can be used to define the upper or lower endpoints of the broader compositional ranges disclosed herein.

Claims (16)

1. A nano silicon powder is in a multilayer structure form of nano silicon core particles/layer A/layer B/layer C or in a multilayer structure form of nano silicon core particles/layer A/layer D, wherein:
the layer A contains Li, at least one of Cu and Ag2SiO3And Sn, the Sn and at least one of Cu and Ag being dispersed at a surface of the silicon nano-core particle, and the Li2SiO3Is coated on the placeAt least a portion of the surface of the nano-silicon core particles;
layer B comprises TiO2And ZrO2And LiAlO and at least one of2And is coated directly and/or indirectly on the surface of the nano-silicon core particles;
layer C comprises carbon and is coated directly and/or indirectly on the surface of the nano-silicon core particle; and
layer D comprises TiO2And ZrO2At least one of, LiAlO2And carbon and coated directly and/or indirectly on the surface of the nano-silicon core particle.
2. The nano-silicon powder of claim 1, wherein one or more of the following are satisfied:
1) the Li is based on the weight of the nano silicon core particles2SiO3The weight percentage of (B) is 0.5-4 wt%;
2) when present, the weight percent of Cu is 0.2-3 wt% based on the weight of the nano-silicon core particles;
3) when present, the weight percent of Ag is 0.2-2 wt% based on the weight of the nano-silicon core particles;
4) the weight percentage of Sn is 0.47-3 wt% based on the weight of the nano silicon core particles;
5) when present, the TiO, based on the weight of the nano-silicon core particle2The weight percentage of the component (A) is 0.5-8 wt%;
6) when present, the ZrO based on the weight of the nano silicon core particles2The weight percentage of the component (A) is 0.2-5 wt%;
7) the LiAlO is based on the weight of the nano silicon core particles2The weight percentage of the component (A) is 0.5-5 wt%; and
8) the weight percentage of the carbon is 3-15 wt% based on the weight of the nano silicon core particles.
3. A method for manufacturing nano silicon powder comprises the following steps:
1) nanometer silicon powder with the grain diameter of 80-120nm is taken as a raw material, nanometer metal oxide and a first lithium source are added,wet grinding with organic solvent as dispersant, wherein the nano metal oxide is CuO and Ag2At least one of O and SnO2；
2) Vacuum drying the slurry obtained in the step 1), and then sintering the slurry for 2 to 8 hours at the temperature of 450-750 ℃ in the protective atmosphere of nitrogen or argon;
3) cooling in protective atmosphere, and then carrying out vibration dry ball milling;
4) dissolving at least one of an organic titanium source and an organic zirconium source, an organic aluminum source and a second lithium source in an organic solvent, adding the powder subjected to ball milling in the step 3), and stirring and grinding by a wet method;
5) vacuum drying the slurry obtained in the step 4), and then sintering the slurry for 2 to 8 hours at the temperature of 300-500 ℃ in the protective atmosphere of nitrogen or argon;
6) cooling in protective atmosphere, and then carrying out vibration dry ball milling;
7) dissolving an organic carbon source in an organic solvent, adding the powder subjected to ball milling in the step 6), and stirring and grinding by a wet method;
8) vacuum drying the slurry obtained in the step 7), and then sintering the slurry for 2 to 8 hours at the temperature of 500-700 ℃ in the protective atmosphere of nitrogen or argon; and
9) cooling in protective atmosphere, and performing vibration dry ball milling to obtain the nano silicon powder in the form of multilayer structure.
4. A method for manufacturing nano silicon powder comprises the following steps:
1) the method comprises the steps of taking nano silicon powder with the particle size of 80-120nm as a raw material, adding nano metal oxide and a first lithium source, and carrying out wet grinding by taking an organic solvent as a dispersing agent, wherein the nano metal oxide is CuO and Ag2At least one of O and SnO2；
2) Vacuum drying the slurry obtained in the step 1), and then sintering the slurry for 2 to 8 hours at the temperature of 450-750 ℃ in the protective atmosphere of nitrogen or argon;
3) cooling in protective atmosphere, and then carrying out vibration dry ball milling;
4) dissolving at least one of an organic titanium source and an organic zirconium source, an organic aluminum source, an organic carbon source and a second lithium source in an organic solvent, adding the powder subjected to ball milling in the step 3), and stirring and grinding by a wet method;
5) vacuum drying the slurry obtained in the step 4), and then sintering the slurry for 2 to 8 hours at the temperature of 500-700 ℃ in the protective atmosphere of nitrogen or argon; and
6) cooling in protective atmosphere, and performing vibration dry ball milling to obtain the nano silicon powder in the form of multilayer structure.
5. The method of claim 3 or 4, wherein one or more of the following is satisfied: A) when adding, 0.25-3.7 weight parts of nano CuO is added in the step 1) based on 100 weight parts of raw material nano silicon powder;
B) when added, 0.2 to 2.1 weight parts of nano Ag is added in the step 1) based on 100 weight parts of raw material nano silicon powder2O；
C) When adding, 0.6 to 3.8 weight parts of nano SnO is added in the step 1) based on 100 weight parts of raw material nano silicon powder2；
D) The first lithium source and the second lithium source are each independently selected from Li2CO3Or LiOH. H2O；
E) Based on 100 weight parts of raw material nano silicon powder, 0.42 to 3.33 weight parts of Li is added in the step 1)2CO3Or 0.75 to 6 parts by weight of LiOH H2O；
F) The organic titanium source is tetra-n-butyl titanate, tetra-isobutyl titanate, tetra-n-propyl titanate or diisopropyl di (acetylacetone) titanate;
G) when adding, based on 100 molar parts of the raw material nano silicon powder, 0.18 to 2.8 molar parts of organic titanium source is added in the step 4);
H) the organic zirconium source is tetra-n-butyl zirconate, tetra-isobutyl zirconate or tetra-n-propyl zirconate;
I) adding 0.045-0.57 molar parts of organic zirconium source in the step 4) when adding based on 100 molar parts of the raw material nano silicon powder;
J) the organic aluminum source is aluminum isopropoxide, aluminum triethoxide, aluminum sec-butoxide or aluminum tert-butoxide;
K) adding 0.21-2.1 molar parts of organic aluminum source in the step 4) based on 100 molar parts of the raw material nano silicon powder;
l) adding 0.28 to 2.8 weight parts of Li based on 100 weight parts of raw material nano silicon powder in the step 4)2CO3Or 0.32 to 3.2 parts by weight of LiOH. H2O；
M) the organic carbon source is one or more selected from citric acid, carboxymethyl cellulose, amylose, saccharides, resins, gelatin, polyaniline, polypyridine and pitch;
n) adding 5 to 25 parts by weight of an organic carbon source to the raw material nano silicon powder in step 7) of claim 3 or step 4) of claim 4 based on 100 parts by mole of the raw material nano silicon powder; and
o) the organic solvent is absolute ethyl alcohol, isopropanol, acetone, N-dimethylacetamide, N-methylpyrrolidone, cyclohexane, chloroform, carbon tetrachloride or silicone oil.
6. A silicon-based negative electrode, which adopts the nano silicon powder as defined in any one of claims 1 to 2 as a negative electrode active material.
7. A method of manufacturing a silicon-based anode, comprising the steps of:
1) preparing anode slurry: adopting the nano silicon powder as defined in any one of claims 1-2 as a negative active material;
2) coating the negative electrode slurry obtained in the step 1) on a negative electrode current collector and drying.
8. The method for manufacturing a silicon-based anode according to claim 7, wherein the nano silicon powder according to any one of claims 1 to 2 as an anode active material, the graphene-carbon nanotube complex NMP slurry as a conductive agent, the solution of carboxyl group-containing polyamic acid as a binder precursor, the coupling agent, the pore-forming agent, and the optional electrolyte wetting agent are added to N-methylpyrrolidone or N, N-dimethylacetamide to form an anode slurry in step 1), and the method further comprises a step of treating in nitrogen or argon at a temperature of 280-.
9. The method of claim 8, wherein the negative active material: conductive agent converted to 100% solids: binder precursor converted to 100% solids 83-90: 1-5: 6-15.
10. The method of claim 8, wherein one or more of the following is satisfied:
1) the addition amount of the pore-forming agent is 5-8 wt% of the negative active material;
2) the addition amount of the coupling agent is 5-10 wt% of the binder precursor converted into 100% of solid;
3) the addition amount of the electrolyte wetting agent is 1-3 wt% of the negative active material;
4) the pore-forming agent is naphthalene, ethylene carbonate EC or biphenyl;
5) the coupling agent is titanate, zirconate or aluminate coupling agent;
6) the electrolyte wetting agent is ethylene carbonate EC; and
7) the negative current collector is copper foil or copper mesh.
11. A lithium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode is the silicon-based negative electrode of claim 6.
12. The lithium ion battery of claim 11, wherein the positive electrode employs high nickel ternary NCM811 or nickel cobalt aluminum NCA as a positive electrode active material.
13. A method of manufacturing a lithium ion battery comprising the steps of:
1) preparing a positive electrode; and
2) assembling the positive electrode, the silicon-based negative electrode of claim 6, a separator, and an electrolyte into a lithium ion battery.
14. The method of claim 13, wherein the preparing of step 1) the positive electrode comprises:
1-1) preparing positive electrode slurry: adopting high-nickel ternary NCM811 or nickel-cobalt-aluminum NCA as a positive active material;
1-2) coating the positive electrode slurry obtained in the step 1-1) on a positive electrode current collector and drying.
15. The method as claimed in claim 14, wherein the high nickel ternary NCM811 or nickel cobalt aluminum NCA as the positive electrode active material, the graphene-carbon nanotube complex NMP slurry as the conductive agent, the solution of the carboxyl group-containing polyamic acid as the binder precursor, the coupling agent, and optionally the electrolyte wetting agent are added to N-methylpyrrolidone or N, N-dimethylacetamide to form the positive electrode slurry in step 1-1), and the preparation of the positive electrode in step 1) further comprises a step of treating in air at a temperature of 280-.
16. The method of claim 15, wherein one or more of the following is satisfied:
1) positive electrode active material by weight: conductive agent converted to 100% solids: binder precursor converted to 100% solids 92-95: 3-6: 4-6;
2) the addition amount of the coupling agent is 5-10 wt% of the binder precursor converted into 100% of solid;
3) the addition amount of the electrolyte wetting agent is 2-8 wt% of the positive electrode active material;
4) the coupling agent is titanate, zirconate or aluminate coupling agent;
5) the electrolyte wetting agent is ethylene carbonate; and
6) the positive current collector is aluminum foil.
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