CN111564633A - Positive electrode active material, negative electrode active material, and preparation methods and applications thereof - Google Patents

Positive electrode active material, negative electrode active material, and preparation methods and applications thereof Download PDF

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Publication number
CN111564633A
CN111564633A CN202010456763.2A CN202010456763A CN111564633A CN 111564633 A CN111564633 A CN 111564633A CN 202010456763 A CN202010456763 A CN 202010456763A CN 111564633 A CN111564633 A CN 111564633A
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active material
silicon
lithium
negative electrode
electrode active
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王元杰
薄晋科
宫颂
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Dalian Zhongbi Energy Technology Co ltd
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Dalian Zhongbi Energy Technology 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/116—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention relates to an electrode material, in particular to a positive electrode active material, a negative electrode active material, a preparation method and an application thereof. The positive electrode active material includes: a ternary material; a nanoparticle carbon conductive chain connected to the surface of the ternary material; wherein the diameter of the nano granular carbon is 1-30 nm; when the positive pole piece is prepared by using the positive active material, no additional conductive agent (especially carbon tube conductive agent) is needed to be added, so that the proportion of the ternary material in the positive pole piece is increased, and the energy density is also increased. The negative active material includes: silicon or silicon monoxide; a nanoparticle carbon conductive chain attached to the surface of the silicon or silica; wherein the diameter of the nano granular carbon is 3-50 nm; when the negative electrode active material is used for preparing a negative electrode plate, a conductive agent (especially a single-walled carbon tube) does not need to be additionally added, the problem of conductive chain fracture caused by volume expansion and contraction of silicon or silicon monoxide in the charging and discharging process can be solved, and the raw material cost is reduced.

Description

Positive electrode active material, negative electrode active material, and preparation methods and applications thereof
Technical Field
The invention relates to an electrode material, in particular to a positive electrode active material, a negative electrode active material, a preparation method and an application thereof.
Background
Electric vehicles have been a trend to replace fuel vehicles, and lithium ion secondary batteries are important components of electric vehicles. Electric vehicles can be classified into pure electric vehicles, plug-in hybrid electric vehicles, 48V micro hybrid electric vehicles, and the like. With the fact that the pure electric vehicle occupies a higher and higher proportion in the electric vehicle, consumers have higher and higher requirements on the endurance mileage.
The negative electrode of the lithium ion secondary battery uses a large amount of graphite materials, the theoretical capacity of the negative electrode is only 372mAh/g, the corresponding battery limit energy density is 200-220 Wh/kg, the requirement that the specific energy of a lithium ion power battery monomer exceeds 260-300 Wh/kg in the prior art cannot be met, and the requirement that a consumer puts forward a long endurance mileage cannot be met.
For this reason, the skilled person proposes to use silicon or silica with higher energy density instead of graphite, the theoretical gram capacity of silicon being 4200mAh/g and the gram capacity of silica being between 1700-2200mAh/g, but the above materials have the following problems in practical use:
compared with graphite, a large number of Solid Electrolyte Interface (SEI) films are formed on the surface of silicon or a silicon oxide material in the first charge-discharge process, so that a part of lithium ions from a positive electrode material and an electrolyte are consumed, irreversible capacity is formed, and finally the first coulombic efficiency of a battery cell is low; in the charging and discharging process, the silicon or the silicon monoxide material is usually accompanied with huge volume expansion, so that the active substance is separated from the conductive agent and the binding agent, and the energy density of the battery is reduced and the cycle life of the battery is shortened; the charge and discharge expansion of silicon or silicon monoxide is too large, and the aluminum shell battery or the soft package battery corresponding to the aluminum shell and the aluminum plastic film is packaged, so that the deformation is too large in the use process, the two batteries are easy to bulge and leak liquid, and the wire harness is extruded to cause the leakage of the wire harness, and safety accidents such as ignition and explosion are easily caused; and fourthly, in order to solve the problem of breakage of a conductive chain of a conductive agent in the negative pole piece caused by overlarge expansion, a person in the field uses a single-walled carbon tube in the negative pole, and a certain amount of metal impurities are introduced in the manufacturing process of the single-walled carbon tube, so that the self-discharge of the single battery is large and the matching rate is low.
In addition, when a high-energy-density battery is prepared, the high-energy-density ternary high-nickel cathode material, such as NCA, NCM and the like, is used by the personnel in the field, and due to the high nickel content of the material, the performance of the battery is deteriorated and the service life is short due to the reaction between the surface of the cathode and an electrolyte in the using process; meanwhile, in order to improve the energy density, a person in the art uses a carbon tube conductive agent in the positive electrode, and compared with the traditional conductive agent, the amount of the carbon tube conductive agent can be reduced, and the amount of the positive electrode can be provided.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a positive active material, a negative active material, a preparation method and application thereof.
As a first object of the present invention, there is provided a positive electrode active material; the surface of the positive active material is provided with a nanoparticle carbon conductive chain structure, when the positive active material is prepared into a positive pole piece, a conductive agent is not required to be added, and the positive pole piece can have good conductive performance, so that safety accidents caused by the conductive agent (especially a carbon tube conductive agent) are effectively solved.
Specifically, the positive electrode active material includes:
1) a ternary material;
2) a nanoparticle carbon conductive chain connected to the surface of the ternary material;
wherein the diameter of the nano granular carbon is 1-30 nm.
As a second object of the present invention, there is provided a method for preparing the above positive electrode active material, comprising:
dispersing the ternary material in a solvent to form slurry; carbonizing the slurry under the action of acetylene;
wherein the carbonization temperature is 1000-2000 ℃.
The invention unexpectedly discovers that the ternary material with a large number of nucleation points on the surface is carbonized at high temperature in acetylene, the nucleation points on the surface of the carbonized ternary material are carbonized and nucleated to form a nanoparticle carbon conductive chain, and the diameter of the nanoparticle carbon is 1-30 nm.
Preferably, in the above technical solution, the mass ratio of the ternary material to the solvent is 1: 0.2 to 5; when the ternary material and the solvent are in the range, the ternary material can be better and uniformly dispersed in the solvent, and the subsequent carbonization into a uniform nano-particle carbon conductive chain is facilitated.
Further, the ternary material is selected from NCA and NxCyMzOne or more of the above; wherein x is more than or equal to 0.8, y is more than 0 and less than or equal to 0.1, and z is more than 0 and less than or equal to 0.1; the invention discovers that the anode active material obtained by selecting one or more ternary materials is better.
Still further, the solvent is N-methylpyrrolidone (NMP); NMP is more favorable for the dispersion of specific ternary materials, and uniform slurry is obtained.
Preferably, the invention finds that the carbonization effect is better when the solid content of the slurry is 16.7-83.3%.
Preferably, the invention finds that when the slurry is dispersed in acetylene in a centrifugal dispersion mode, the acetylene can be uniformly and fully contacted with the slurry, and a product with better effect is obtained.
As a preferred option of the above technical solution, the present invention finds that the carbonization time also has unpredictable influence on the carbonization effect; particularly, when the carbonization time is 5-10 s, the carbonization effect is best; the carbonization time is too long, the structure of the nanoparticle carbon conductive chain is incomplete, the carbonization time is too short, the structure of the nanoparticle carbon conductive chain is complex, and the diameter of the nanoparticle carbon is not uniform.
As a preferred technical scheme of the invention, the carbonization process is carried out in an acetylene gas carbonization furnace, the acetylene gas carbonization furnace is of an upper-layer and lower-layer structure, the upper layer is carbonized at high temperature, and the lower layer is cooled.
As a third object of the present invention, there is provided a positive electrode sheet; the positive pole piece comprises the positive active material.
Preferably, the positive electrode plate further comprises a lithium supplement additive; the lithium supplement additive is selected from one or more of lithium phosphate, lithium pyrophosphate and lithium metaphosphate; the lithium supplement additive accounts for 0.5-2% of the total mass of the positive pole piece.
The invention further discovers that the lithium supplement additive with specific content is mixed into the positive pole piece, so that the first charging efficiency of the battery can be effectively improved, and the capacity of the battery is improved, namely the energy density of the battery is improved.
Preferably, the density of the positive active material in the positive pole piece is 200-500 mg/10cm2。
As the preferred technical scheme of the invention, the positive pole piece also comprises an adhesive and a current collector; the binder is selected from one or more of polyvinylidene fluoride (PVDF), styrene butadiene rubber latex and poly (acrylonitrile); the current collector is an aluminum foil or a carbon-coated aluminum foil.
As a fourth object of the present invention, there is provided an anode active material; the surface of the negative active material is provided with a nanoparticle carbon conductive chain structure, and when the negative active material is prepared into a negative pole piece, a conductive agent is not required to be added, so that the problem of conductive chain fracture of the conductive agent caused by over-expansion in the charge and discharge processes of silicon or silicon monoxide is effectively solved.
Specifically, the anode active material includes:
1) silicon or silicon monoxide;
2) a nanoparticle carbon conductive chain attached to the surface of the silicon or silica;
wherein the diameter of the nano granular carbon is 3-50 nm.
As a fifth object of the present invention, there is provided a method for preparing the anode active material described above, comprising:
dispersing the silicon or the silicon monoxide subjected to acid washing in water to form slurry; carbonizing the slurry under the action of acetylene;
wherein the carbonization temperature is 1000-2000 ℃.
The invention unexpectedly discovers that a large number of nucleation points are formed on the surface of silicon or silicon monoxide after acid washing, the silicon or silicon monoxide with a large number of nucleation points on the surface is carbonized at high temperature in acetylene, the nucleation points on the surface of the silicon or silicon monoxide after carbonization are carbonized and nucleated to form a nano-particle carbon conductive chain, and the diameter of the nano-particle carbon is between 3 and 50 nm.
Preferably, in the above aspect, the mass ratio of the silicon or the silicon monoxide to the acid is 1: 1.5-2.5; preferably, the acid is 1-20% hydrofluoric acid;
the invention discovers that nucleation points on the surface of silicon or silicon oxide can be uniformly exposed after the silicon or silicon oxide is subjected to acid washing by 1-20% hydrofluoric acid, and the subsequent carbonization of the silicon or silicon oxide into uniform nano-particle carbon conductive chains is facilitated.
Preferably, the acid-washed silicon or silica is washed with water and dried, and then dispersed in water to form a slurry; the mass ratio of the dried material to water is 1: 0.2 to 5.
Preferably, when the acid washing time is 1-2 hours, the nucleation points are exposed most uniformly, which is beneficial to the subsequent carbonization to form a nano-particle carbon conductive chain; the acid washing time is too long, the exposure of nucleation points is complex and uneven, and the subsequent carbonization is caused to form a nanoparticle carbon conductive chain with a complex structure; the acid washing time is too short, the exposure of nucleation points is less, and the subsequent carbonization is caused to form a nano particle carbon conductive chain with an incomplete structure.
Preferably, the solid content of the slurry is 16.7-83.3%; when the solid content of the slurry is 16.7-83.3%, the carbonization effect is better.
Preferably, the invention finds that when the slurry is dispersed in acetylene in a centrifugal dispersion mode, the acetylene can be uniformly and fully contacted with the slurry, and a product with better effect is obtained.
As a preferred option of the above technical solution, the present invention finds that the carbonization time also has unpredictable influence on the carbonization effect; particularly, when the carbonization time is 5-10 s, the carbonization effect is best; the carbonization time is too long, the structure of the nanoparticle carbon conductive chain is incomplete, the carbonization time is too short, the structure of the nanoparticle carbon conductive chain is complex, and the diameter of the nanoparticle carbon is not uniform.
As a preferred technical scheme of the invention, the carbonization process is carried out in an acetylene gas carbonization furnace, the acetylene gas carbonization furnace is of an upper-layer and lower-layer structure, the upper layer is carbonized at high temperature, and the lower layer is cooled.
As a sixth object of the present invention, there is provided a negative electrode tab; the negative electrode plate comprises the negative electrode active material.
Preferably, in the above technical solution, the negative electrode plate further includes graphite; the graphite is selected from one or more of artificial graphite, natural graphite and mesocarbon microbeads;
in a specific embodiment, the active material of the negative electrode tab consists of the negative electrode active material and graphite.
Preferably, in the technical scheme, the sum of the negative active material and the graphite has a capacity of 400-800 mAh/g in terms of the total capacity of the negative electrode sheet; wherein the mass ratio of the negative electrode active material to the graphite is 1: 0.004-2.
As a preferred technical scheme of the invention, the negative pole piece also comprises a binder and a current collector; the binder is selected from one or more of carboxymethyl cellulose (CMC), styrene butadiene rubber latex (SBR) and polyvinylidene fluoride polynitrile; the current collector is a copper foil.
In a preferred embodiment of the present invention, the density of the negative electrode active material in the negative electrode sheet is controlled to a B C/D, where a is a negative electrode excess coefficient, B is a positive electrode active material density, C is a positive electrode gram capacity, and D is a negative electrode active material gram capacity.
As a seventh object of the present invention, there is provided a lithium ion secondary battery; the lithium ion battery comprises the positive pole piece, the negative pole piece, a diaphragm and electrolyte.
Preferably, the diaphragm is selected from one or more of polypropylene, polyethylene, ceramic and polyvinylidene fluoride.
In specific embodiments, the separator may be a polypropylene single-layer film, a polyethylene single-layer film, or a polypropylene-polyethylene-polypropylene three-layer composite film; or a composite diaphragm composed of any diaphragm and ceramic, or a ceramic gluing diaphragm composed of any diaphragm and ceramic and polyvinylidene fluoride.
Preferably, the electrolyte comprises a solvent, a soluble lithium salt and an additive; the solvent is one or more selected from ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate and ethyl acetate; the soluble lithium salt is lithium hexafluorophosphate; the additive is selected from one or more of propane sultone, vinylene carbonate, lithium bis-fluorosulfonylimide, lithium difluoro-oxalato-borate, methylene methyl disulfonate, lithium difluoro-oxalato-phosphate and fluoro-carbonate.
As a preferable technical scheme of the invention, the steel shell is used as the sealing structure of the lithium ion secondary battery.
The invention has the beneficial effects that:
(1) forming a nano-particle carbon conductive chain network structure on the surface of the ternary material in high-temperature acetylene gas to obtain a positive active material; when the positive pole piece is prepared by using the positive active material, no additional conductive agent (especially carbon tube conductive agent) is needed to be added, so that the proportion of the ternary material in the positive pole piece is increased, and the energy density is also increased.
In addition, the positive pole piece does not adopt a conductive agent (particularly a carbon tube conductive agent containing metal impurities), so that the self-discharge of the battery and the micro short circuit in the use process are greatly reduced, and the safety of the battery is improved.
In addition, when the treated ternary material is used as slurry, the dosage of the NMP solvent is reduced by 20-35%, the dosage of the pole piece binder is reduced by 30-50%, and the manufacturing cost of the battery is reduced.
(2) Forming a nano-particle carbon conductive chain network structure on the surface of the silicon or the silicon monoxide subjected to acid washing in high-temperature acetylene gas to obtain a cathode active material; when the negative electrode active material is used for preparing a negative electrode plate, a conductive agent (especially a single-walled carbon tube) does not need to be additionally added, the problem of conductive chain fracture caused by volume expansion and contraction of silicon or silicon monoxide in the charging and discharging process can be solved, and the raw material cost is reduced.
Moreover, the surface nano-particle carbon conductive chain of silicon or silicon monoxide can effectively buffer the expansion of the pole piece; meanwhile, the self-discharge of the battery and the micro short circuit in the use process are reduced, and the safety of the battery is improved.
(3) The lithium supplement additive is added into the positive pole piece, and an SEI film can be effectively generated on the surface of silicon or silicon oxide in the first charging process of the battery consisting of the silicon or silicon oxide and graphite mixed electrode, so that the first efficiency of the battery is improved, the capacity of the battery is improved, and the energy density of the battery is improved.
(4) The lithium ion secondary battery adopts the steel shell as a sealing structure, and compared with a soft package battery and a square shell battery, the size of the battery is basically unchanged after long circulation.
Detailed Description
The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
Example 1
The present embodiment provides a positive electrode active material, and a method for preparing the positive electrode active material includes:
material N to be purchased0.8C0.1M0.1With NMP solvent according to 1: 1.5, preparing slurry with solid content of 40 percent; adding the slurry into an acetylene gas carbonization furnace in a centrifugal dispersion mode, wherein the carbonization furnace is of an upper-layer structure and a lower-layer structure, the upper layer is carbonized at high temperature, and the lower layer is cooled; the carbonization temperature of acetylene gas is 1500 ℃, the carbonization time is 6 seconds, and the natural cooling mode is adopted for cooling.
And forming a nano-particle carbon conductive chain on the surface of the obtained positive electrode active material, wherein the diameter of the nano-particle carbon is 1-15 nm.
Example 2
This example provides a positive electrode plate, which is prepared from the positive active material, the binder HSV900, and the lithium supplement additive LiPO of example 13And a current collector;
among them, the positive electrode active material of example 1 was mixed with the binder HSV900 and the lithium supplement additive LiPO3The mass ratio of (A) to (B) is 98: 1: 1; the current collector is an aluminum foil with the thickness of 12 mu m; the density of the positive active material in the positive pole piece is controlled to be 500mg/10cm2。
Example 3
The present embodiment provides an anode active material, and a preparation method of the anode active material includes:
silicon powder with the particle size distribution of 50-100 nm is firstly subjected to acid cleaning for 1.5h by using 15% HF solution, and then is washed and dried to form nucleation points; the dried material was mixed with water at a ratio of 1: 2, dispersing in proportion to prepare slurry with the solid content of 33.3%, adding the slurry into an acetylene gas carbonization furnace in a centrifugal dispersion mode, wherein the carbonization furnace is of an upper-layer structure and a lower-layer structure, the upper layer is carbonized at high temperature, and the lower layer is cooled; the carbonization temperature of acetylene gas is 1500 ℃, the carbonization time is 6 seconds, and the natural cooling mode is adopted for cooling.
And forming a nano-particle carbon conductive chain on the surface of the obtained cathode active material, wherein the diameter of the nano-particle carbon is 5-30 nm.
Example 4
The present embodiment provides a negative electrode tab, which is composed of the negative active material, natural graphite, binder CMC, binder SBR, and current collector in embodiment 3;
wherein, the mass ratio of the negative electrode active material, the natural graphite, the binder CMC and the binder SBR in the embodiment 3 is 97.1: 0.4: 1.5: 1.0; the density of the negative electrode active material in the negative electrode pole piece is controlled to be a B C/D, wherein a is a negative electrode excess coefficient, B is the density of the positive electrode active material, C is the gram capacity of the positive electrode, and D is the density of the negative electrode active material.
Through the calculation, the method has the advantages that,the density of the negative active material in the negative pole piece is 225mg/10cm2。
Example 5
This example provides a lithium ion secondary battery, the lithium ion is composed of the positive electrode sheet of example 2, the negative electrode sheet of example 4, a separator, and an electrolyte;
wherein the diaphragm is a polyethylene single-layer film, ceramic and a ceramic gluing diaphragm consisting of PVDF;
the solvent of the electrolyte is ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate, the soluble lithium salt is lithium hexafluorophosphate, and the additive is propane sultone, vinylene carbonate and lithium bis-fluorosulfonyl imide.
The lithium ion secondary battery is a 32140 steel shell lithium ion secondary battery, the outer diameter of the battery is 32mm, the height of the battery is 140mm, and the battery capacity is 25.5 Ah.
Comparative example 1
This comparative example provides a lithium ion secondary battery, differing from example 5 only in that:
1) the positive pole pieces are different: from N0.8C0.1M0.1The binding agent HSV900 and the carbon tube are mixed according to the ratio of 96.5: 2: 1.5;
2) the negative pole pieces are different: silicon powder distributed at 50-100 nm: single-walled carbon tubes: binder CMC: binder SBR according to 97.3: 0.2: 1.5: 1.0 in proportion.
Test example 1
This test example was conducted for testing the performance of the lithium ion secondary batteries of example 5 and comparative example 1; the test results are shown in table 1;
table 1 performance line test of lithium ion secondary batteries of example 5 and comparative example 1
Figure BDA0002509497440000101
Wherein the negative electrode expansion rate (negative electrode thickness under full charge-uncharged negative electrode thickness)/uncharged negative electrode thickness is 100%;
capacity retention rate (last cycle discharge capacity-first cycle discharge capacity)/first cycle discharge capacity 100%;
monthly self-discharge rate (discharge capacity after storage-discharge capacity before storage)/discharge capacity before storage/month 100%.
Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims (10)

1. A positive electrode active material, comprising:
1) a ternary material;
2) a nanoparticle carbon conductive chain connected to the surface of the ternary material;
wherein the diameter of the nano granular carbon is 1-30 nm.
2. A method for producing the positive electrode active material according to claim 1, comprising:
dispersing the ternary material in a solvent to form slurry; carbonizing the slurry under the action of acetylene;
wherein the carbonization temperature is 1000-2000 ℃.
3. The preparation method according to claim 2, wherein the mass ratio of the ternary material to the solvent is 1: 0.2 to 5; preferably, the ternary material is selected from NCA, NxCyMzOne or more of the above; wherein x is more than or equal to 0.8, y is more than 0 and less than or equal to 0.1, and z is more than 0 and less than or equal to 0.1; more preferably, the solvent is N-methylpyrrolidone;
and/or the solid content of the slurry is 16.7-83.3%;
and/or, the slurry is dispersed into acetylene in a centrifugal dispersion manner;
and/or the carbonization time is 5-10 s.
4. A positive electrode sheet comprising the positive electrode active material according to claim 1;
preferably, the positive pole piece further comprises a lithium supplement additive; the lithium supplement additive is selected from one or more of lithium phosphate, lithium pyrophosphate and lithium metaphosphate; the lithium supplement additive accounts for 0.5-2% of the total mass of the positive pole piece;
more preferably, the density of the positive active material in the positive pole piece is 200-500 mg/10cm2。
5. An anode active material, comprising:
1) silicon or silicon monoxide;
2) a nanoparticle carbon conductive chain attached to the surface of the silicon or silica;
wherein the diameter of the nano granular carbon is 3-50 nm.
6. The method for preparing the negative active material of claim 5, comprising:
dispersing the silicon or the silicon monoxide subjected to acid washing in water to form slurry; carbonizing the slurry under the action of acetylene;
wherein the carbonization temperature is 1000-2000 ℃.
7. The production method according to claim 5, wherein the mass ratio of the silicon or the silicon monoxide to the acid is 1: 1.5-2.5; preferably, the acid is 1-20% hydrofluoric acid;
and/or, after washing and drying the silicon or the monox after acid washing, dispersing the silicon or the monox in water to form slurry; the mass ratio of the dried material to water is 1: 0.2 to 5;
and/or the pickling time is 1-2 h;
and/or the solid content of the slurry is 16.7-83.3%;
and/or, the slurry is dispersed into acetylene in a centrifugal dispersion manner;
and/or the carbonization time is 5-10 s.
8. A negative electrode sheet comprising the negative electrode active material according to claim 5;
preferably, the negative electrode plate further comprises graphite; the graphite is selected from one or more of artificial graphite, natural graphite and mesocarbon microbeads;
more preferably, the sum of the negative active material and the graphite has a capacity of 400-800 mAh/g in terms of the total capacity of the negative electrode sheet; wherein the mass ratio of the negative electrode active material to the graphite is 1: 0.004-2.
9. A lithium ion secondary battery comprising the positive electrode sheet according to claim 4, the negative electrode sheet according to claim 8, a separator and an electrolyte.
10. The lithium ion secondary battery according to claim 9, wherein the separator is selected from one or more of polypropylene, polyethylene, ceramic, polyvinylidene fluoride;
and/or the electrolyte comprises a solvent, a soluble lithium salt and an additive; the solvent is one or more selected from ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate and ethyl acetate; the soluble lithium salt is lithium hexafluorophosphate; the additive is selected from one or more of propane sultone, vinylene carbonate, lithium bis-fluorosulfonylimide, lithium difluoro-oxalato-borate, methylene methyl disulfonate, lithium difluoro-oxalato-phosphate and fluoro-carbonate.
CN202010456763.2A 2020-05-26 2020-05-26 Positive electrode active material, negative electrode active material, and preparation methods and applications thereof Pending CN111564633A (en)

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