CN116314587A - Sodium ion battery negative plate and sodium ion battery - Google Patents

Sodium ion battery negative plate and sodium ion battery Download PDF

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Publication number
CN116314587A
CN116314587A CN202310242904.4A CN202310242904A CN116314587A CN 116314587 A CN116314587 A CN 116314587A CN 202310242904 A CN202310242904 A CN 202310242904A CN 116314587 A CN116314587 A CN 116314587A
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negative electrode
sodium ion
ion battery
electrode sheet
carbon
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周勇
吴志荣
尚佩
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Shanghai Yangguang 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
    • H01M4/13—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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • 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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • 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
    • 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

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Abstract

The invention belongs to the technical field of sodium ion batteries, and particularly relates to a sodium ion battery negative plate and a sodium ion battery. The sodium ion battery negative electrode sheet includes: a negative electrode current collector; a negative electrode active material layer coated on at least one surface of the negative electrode current collector; the negative electrode active material layer comprises the following components in percentage by weight: 90-96% of hard carbon, 1-3% of conductive agent, 1-3% of thickening agent, 1-4% of binder and 0.1-0.8% of preservative; and the hard carbon particle diameter distribution D50 (μm), tap density A (g/cm) 3 ) And a specific surface area B (m 2 /g) satisfies the following relation: d50 is more than or equal to 3.0 and less than or equal to 9.0,0.1, A/B is more than or equal to 1. Compared with the prior art, the sodium ion battery negative plate provided by the invention has the advantages of flexibility and stripping forceAnd the liquid retention rate is obviously improved, and the problem that the safety performance of the pole piece is reduced due to the consumption of electrolyte is solved.

Description

Sodium ion battery negative plate and sodium ion battery
Technical Field
The invention belongs to the technical field of sodium ion batteries, and particularly relates to a sodium ion battery negative plate and a sodium ion battery.
Background
Along with the high-order vibration of lithium salt price, the heat of the sodium ion battery serving as an alternative scheme is continuously increased, and the sodium ion battery has wide application prospect in the energy storage field due to the advantages of abundant sodium resources, low cost, good safety performance and the like; for sodium ion batteries, the negative electrode material plays an important role in loading and releasing sodium ions, which directly affects the overall kinetic properties of the battery, such as rate capability, power density, and the like. The existing sodium ion battery negative plate has poor stripping force and flexibility, so that the qualification rate of the manufacturing process is low, the requirements of high-speed winding manufacture and mass production cannot be met, along with the increase of the circulation times, the electrolyte on the surface of the negative plate is continuously consumed and decomposed, the circulation performance is rapidly reduced, the self-discharge of the manufactured battery core is large, the discharge heating is serious, and even the safety problem can be possibly caused.
Currently, the negative electrode materials of sodium ion batteries are mainly divided into five types: carbon-based materials, titanium-based materials, alloy materials, organic compounds, other systems, etc., and carbon-based materials have more application foundation due to cost and performance comprehensive cost performance advantages. The carbon-based negative electrode can be divided into graphite materials, amorphous carbon materials and nano carbon materials according to the microstructure of carbon atoms, and the amorphous carbon materials have higher specific sodium storage capacity and low cost, and are the main choice of the current negative electrode materials.
Amorphous carbon is also classified into hard carbon, soft carbon, etc., and a larger amount of binder needs to be added in order to ensure the adhesion between the active material and the pole piece due to the larger specific surface area, so that the adding ratio of the active material is lower, resulting in problems of rising cost, lower energy density, etc. In addition, the electrolyte on the surface of the negative electrode sheet is gradually depleted along with the continuous increase of the cycle times, so that the cycle performance is rapidly deteriorated.
In view of the foregoing, it is necessary to provide a solution to the above-mentioned problems.
Disclosure of Invention
In view of the problems existing in the related art, the purpose of the application is to provide a sodium ion battery negative plate, which obviously improves the flexibility, stripping force and liquid retention rate of the plate, and solves the problem that the safety performance of the plate is reduced due to the consumption of electrolyte.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
according to an aspect of the present application, there is provided a sodium ion battery negative electrode sheet comprising:
a negative electrode current collector;
a negative electrode active material layer coated on at least one surface of the negative electrode current collector; the negative electrode active material layer comprises the following components in percentage by weight: 90-96% of hard carbon, 1-3% of conductive agent, 1-3% of thickening agent, 1-4% of binder and 0.1-0.8% of preservative;
and the hard carbon particle diameter distribution D50 (μm), tap density A (g/cm) 3 ) And a specific surface area B (m 2 /g) satisfies the following relation:
3.0≤D50≤9.0，0.1＜A/B＜1。
preferably, the hard carbon particle size distribution D50 is 5.0.ltoreq.D50.ltoreq.7.0 μm, and the tap density A is not less than 0.9g/cm 3 Specific surface area B > 2.5m 2 /g。
Preferably, the conductive agent includes at least one of carbon black, acetylene black, ketjen black, carbon nanotubes, carbon fibers, and graphene.
Preferably, the binder is at least one of aqueous polyacrylic acid derivative adhesive (PAAd), styrene-butadiene rubber emulsion and polytetrafluoroethylene emulsion.
Preferably, the thickener is sodium carboxymethyl cellulose (CMC).
Preferably, the preservative is a functional polymer SFC.
Preferably, the peel strength of the negative electrode sheet is D (N/m), wherein 15.0 < D < 22.5.
Preferably, the surface resistance of the negative plate is E (mΩ), wherein 0.90 < E < 1.50.
According to another aspect of the application, the application further provides a sodium ion battery, which comprises a positive plate, a negative plate, an isolating film and electrolyte, wherein the negative plate is the negative plate of the sodium ion battery.
Preferably, the wetting angle of the electrolyte is θ, wherein 41 ° < θ < 55 °.
Compared with the prior art, the technical scheme provided by the application at least can achieve the following beneficial effects:
the novel aqueous polyacrylic acid derivative adhesive (PAAd) is adopted as the negative electrode plate adhesive, the carboxyl content in the structure of the novel aqueous polyacrylic acid derivative adhesive is higher than CMC, the novel aqueous polyacrylic acid derivative adhesive can form stronger hydrogen bond action with active material materials with hydroxyl groups and other groups on the surface, the more uniform coating than CMC is promoted to be formed on the surface of an electrode, the adhesive force between the adhesive and hard carbon particles and between the hard carbon particles and a substrate can be improved, the flexibility and the peeling strength of a pole plate are improved, the hard carbon particles and the substrate also have stronger adhesive force, and a sodium storage space which is enough stable for removing sodium ions from a positive electrode can be provided; in addition, the functional polymer SFC is added in the pole piece formula, wherein the anionic macromolecules have an affinity effect with the electrolyte on the surface of the pole piece, and can effectively lock the electrolyte. The application solves the problem that the battery has low cycle performance and safety performance due to poor flexibility, stripping force and liquid retention.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a graph of peel strength test data for sodium ion battery negative plates of examples 1 to 4 of the present application.
Fig. 2 is a graph of the liquid absorption test data of the negative electrode sheet of the sodium ion battery in examples 1 to 4 of the present application.
Fig. 3 is a graph of negative sheet resistance test data for sodium ion batteries of examples 1-4 of the present application.
Fig. 4 is a graph of the cycle performance test data of the negative electrode sheets of the sodium ion batteries of examples 1 to 4 of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
According to an aspect of the present application, there is provided a sodium ion battery negative electrode sheet comprising:
a negative electrode current collector; the current collector is carbon-coated aluminum foil, and after carbon coating treatment is carried out on the surface of the aluminum foil, the carbon-coated layer can play a role of a bridge, the anode active material and the aluminum foil are tightly bonded, and particles are mutually embedded, so that the conductivity of the anode piece is improved, and finally the internal resistance of the battery is reduced. In addition, the carbon coating can lead the surface of the aluminum foil to be uneven, and increases the contact area between active substances in the electrolyte and the negative current collector, thereby transferring electrons faster and collecting current when high current is charged and discharged rapidly, and improving the rate performance and charge and discharge performance of the battery;
a negative electrode active material layer coated on at least one surface of the negative electrode current collector; the negative electrode active material layer comprises the following components in percentage by weight: 90-96% of hard carbon, 1-3% of conductive agent, 1-3% of thickening agent, 1-4% of binder and 0.1-0.8% of preservative;
wherein, the content of the components in the negative electrode active material layer can be regulated according to the performance requirement, for example, the hard carbon can be 90%, 91%, 92%, 93%, 94% and 96%; the conductive agent can be 1%, 1.5%, 2%, 2.5%, 3%; the thickener can be 1%, 1.5%, 2%, 2.5%, 3%; the binder may be 1%, 1.5%, 2%, 2.5%, 3%, 4%; the liquid retention agent can be 0.1%, 0.3%, 0.5%, 0.6%, 0.8%;
and the hard carbon particle diameter distribution D50 (μm), tap density A (g/cm) 3 ) And a specific surface area B (m 2 /g) satisfies the following relation:
the D50 is more than or equal to 3.0 and less than or equal to 9.0,0.1 and less than A/B is less than 1, and the sodium ion battery prepared from the hard carbon meeting the relation has higher cycle performance and rate capability.
In one embodiment according to the present application, the hard carbon particle size distribution D50 is 5.0 to 7.0 μm, tap density A. Gtoreq.0.9 g/cm 3 Specific surface area B > 2.5m 2 Preferably, the tap density is 0.9g/cm 3 ≤A≤2.5g/cm 3 Specific surface area of 2.5m 2 /g＜B＜9m 2 And/g. The hard carbon has small particle size, large specific surface area, large tap density and high conductivity, is favorable for rapidly removing and embedding sodium ions during discharging, and improves the rate capability of the sodium ion battery. Because the arrangement of crystals in the hard carbon structure is disordered and disordered, the pores are many, and sodium can be stored in the interlayer, closed micropores, the surface and defect sites of the graphite sheet, the graphite sheet has high isotropy, so that sodium ions can be embedded and migrated from various angles, and the rate performance and the cycle life are improved to a great extent.
In an embodiment according to the present application, the conductive agent includes at least one of carbon black, acetylene black, ketjen black, carbon nanotubes, carbon fibers and graphene, and a certain amount of conductive agent is added during the pole piece manufacturing process to increase the conductivity of electrons and sodium ions, and the electron transmission rate is accelerated by forming a conductive network on the surface of the active material, and at the same time, the electrolyte can be absorbed and maintained, so as to provide more electrolyte interfaces for sodium ions, thereby improving the battery charging efficiency and cycle life.
In an embodiment according to the present application, the binder is at least one of an aqueous polyacrylic acid derivative binder (PAAd) manufactured by fujian blue sea black stone new material science and technology limited, styrene-butadiene rubber emulsion, polytetrafluoroethylene emulsion, which has the following advantages: 1) Hardly swells in electrolyte, and the electrode plate has stable structure in the charge and discharge process; 2) The carboxyl content in the structure is higher than CMC, so that the structure can form stronger hydrogen bond action with active material materials with hydroxyl groups and other groups on the surface, and the electrode surface is promoted to form more uniform coating than CMC; 3) A denser film can be formed in the electrode sheet, and the electric contact between the active substance and the current collector is increased; 4) The adhesive force between the adhesive and the hard carbon particles and between the hard carbon particles and the base material can be improved, and the flexibility of the pole piece is improved, so that the manufacturing and processing capacity of the pole piece is improved.
In an embodiment according to the present application, the thickener is sodium carboxymethyl cellulose (CMC).
In an embodiment according to the present application, the liquid retention agent is a functional polymer SFC, which is produced by Shanghai's win industry limited company, and is an anionic polymer emulsion with a large particle size, and is mainly significant in improving the liquid retention performance, the pole piece wettability, the high-temperature storage, the high-temperature circulation, the internal resistance of the battery, and the like of the battery.
In an embodiment according to the present application, the peel strength of the negative electrode sheet is D (N/m), wherein 15.0 < D < 22.5, for example D may be 15.0N/m, 17.0N/m, 19.0N/m, 21.0N/m, 22.5N/m.
In an embodiment according to the present application, the surface resistance of the negative electrode sheet is E (mΩ), where 0.90 < E < 1.50, e.g. E may be 0.90mΩ, 0.96mΩ, 1.10mΩ, 1.30mΩ, 1.50mΩ.
According to another aspect of the application, the invention further provides a sodium ion battery, which comprises a positive plate, a negative plate, an isolating film and electrolyte, wherein the negative plate is the negative plate of the sodium ion battery.
The positive plate adopts N-methyl pyrrolidone (NMP) as a solvent to prepare active material slurry, conductive adhesive is added into the active material slurry to stir the active material slurry to prepare the positive plate, and then the positive plate is prepared into the pole plate through the procedures of coating, drying and the like.
The isolating film is at least one of polypropylene film, polyethylene film, polyester substrate and polyacrylonitrile.
The electrolyte comprises sodium salt, carbonate solvent and additive. Wherein the carbonate solvent comprises a cyclic carbonate solvent and a chain carbonate solvent; sodium salt is NaPF 6 、NaClO 4 、NaBF 4 、NaFSI、NaTFSI、NaSO 3 CF 3 And Na (CH) 3 )C 6 H 4 SO 3 At least one of (a) and (b); the additive comprises a first additive and a second additive, wherein the first additive is fluoroethylene carbonate or bifluoroethylene carbonate, and the second additive is fluorocyclotriphosphazene,At least one of hexafluoro-cyclotriphosphazene, pentafluoroethoxy-cyclotriphosphazene and pentafluorophenoxy-cyclotriphosphazene.
In an embodiment according to the present application, the wetting angle of the electrolyte is θ, wherein 41 ° < θ < 55 °; for example, θ may be 41 °, 43 °, 45 °, 48 °, 50 °, 52 °, 55 °.
The technical scheme and beneficial effects of the present application will be described in detail below with reference to specific examples and comparative examples.
Example 1
The negative plate of the sodium ion battery provided in this embodiment includes:
carbon-coated aluminum foil for negative current collector;
a negative electrode active material layer coated on at least one surface of the negative electrode current collector carbon-coated aluminum foil; the negative electrode active material layer comprises the following components in percentage by weight: 94.3% of hard carbon, 1.5% of conductive agent, 1.4% of thickening agent, 2.5% of binder and 0.3% of preservative;
and hard carbon particle size distribution D50 (. Mu.m), tap density A (g/cm) 3 ) And a specific surface area B (m 2 /g) is required to satisfy the following relation: d50 is more than or equal to 3.0 and less than or equal to 9.0,0.1, A/B is more than or equal to 1; preferably, the hard carbon particle size distribution D50 is 5.0.ltoreq.D50.ltoreq.7.0 μm, and the tap density A is not less than 0.9g/cm 3 Specific surface area B > 2.5m 2 /g。
The preparation method of the sodium ion battery negative plate comprises the following steps:
the preparation method comprises the steps of mixing hard carbon serving as a negative electrode active substance, carbon black serving as a conductive agent, CMC serving as a thickener, PAAd serving as a binder and SFC serving as a liquid retention agent according to the mass ratio of 94.3%,1.5%, 1.4%, 2.5% and 0.3% with N-methylpyrrolidone serving as a solvent and pure water to form negative electrode slurry, coating the negative electrode slurry on the surface of carbon-coated aluminum foil of a current collector, and finally forming a negative electrode plate through rolling, slitting and tabletting.
The negative electrode plate, the positive electrode plate, the diaphragm and the electrolyte are matched to prepare the sodium ion battery according to the conventional process.
Example 2
The preparation of the negative electrode sheet was different from example 1.
The preparation method comprises the steps of mixing the anode active substance hard carbon, the conductive agent acetylene black, the thickener CMC, the binder styrene-butadiene rubber emulsion SBR and the liquid retention agent SFC according to the mass ratio of 93.3%,1.7%, 1.4%, 2.4% and 0.4% with the solvent N-methylpyrrolidone and pure water to form anode slurry, coating the anode slurry on the surface of the carbon-coated aluminum foil of the current collector, and finally forming the anode plate through rolling, slitting and tabletting.
The remainder is the same as embodiment 1 and will not be described in detail here.
Example 3
The preparation of the negative electrode sheet was different from example 1.
The preparation method comprises the steps of mixing the anode active substance hard carbon, a conductive agent carbon nano tube, a thickening agent CMC, a binder polytetrafluoroethylene emulsion (PTFE) and a preservative SFC according to the mass ratio of 94.6%,1.4%, 1.3%, 2.5% and 0.3%, a solvent N-methylpyrrolidone and pure water to form anode slurry, coating the anode slurry on the surface of a carbon-coated aluminum foil of a current collector, and finally forming an anode plate through rolling, slitting and tabletting.
The remainder is the same as embodiment 1 and will not be described in detail here.
Example 4
The preparation of the negative electrode sheet was different from example 1.
And mixing the anode active material hard carbon, the conductive agent graphene, the thickener CMC, the binder PAAd and the liquid retention agent SFC according to the mass ratio of 94.3%,1.5%, 1.4%, 2.5% and 0.3% with the solvent N-methylpyrrolidone and pure water to obtain anode slurry, coating the anode slurry on the surface of the carbon-coated aluminum foil of the current collector, and finally forming the anode plate through rolling, slitting and tabletting.
The remainder is the same as embodiment 1 and will not be described in detail here.
Example 5
The preparation of the negative electrode sheet was different from example 1.
The preparation method comprises the steps of mixing hard carbon serving as a negative electrode active substance, acetylene black serving as a conductive agent, CMC serving as a thickening agent, SBR serving as a binder and SFC serving as a liquid retention agent according to the mass ratio of 90.5%,1.8%, 2.0%, 1.9% and 0.5% with N-methylpyrrolidone serving as a solvent and pure water to form negative electrode slurry, coating the negative electrode slurry on the surface of carbon-coated aluminum foil of a current collector, and finally forming a negative electrode plate through rolling, slitting and tabletting.
The remainder is the same as embodiment 1 and will not be described in detail here.
Example 6
The preparation of the negative electrode sheet was different from example 1.
The preparation method comprises the steps of mixing the anode active substance hard carbon, conductive agent carbon black, thickener CMC, binder styrene butadiene rubber emulsion SBR and liquid retention agent SFC with solvent N-methyl pyrrolidone and pure water according to the mass ratio of 93.5%,1.6%, 1.8%, 2.8% and 0.3% respectively to obtain anode slurry, coating the anode slurry on the surface of a carbon-coated aluminum foil of a current collector, and finally forming an anode plate through rolling, slitting and tabletting.
The remainder is the same as embodiment 1 and will not be described in detail here.
Example 7
The preparation of the negative electrode sheet was different from example 1.
The preparation method comprises the steps of mixing the anode active substance hard carbon, conductive agent carbon fiber, thickener CMC, binder PAAd and liquid retention agent SFC according to the mass ratio of 92.1%,1.2%, 1.6%, 3.0% and 0.5% with solvent N-methylpyrrolidone and pure water to obtain anode slurry, coating the anode slurry on the surface of carbon-coated aluminum foil of a current collector, and finally forming an anode plate through rolling, slitting and tabletting.
The remainder is the same as embodiment 1 and will not be described in detail here.
Example 8
The preparation of the negative electrode sheet was different from example 1.
The preparation method comprises the steps of mixing the anode active substance hard carbon, a conductive agent carbon nano tube, a thickening agent CMC, a binder styrene-butadiene rubber emulsion SBR and a liquid retention agent SFC according to the mass ratio of 94.6%,1.8%, 2.3%, 3.2% and 0.4% with solvent N-methylpyrrolidone and pure water to form anode slurry, coating the anode slurry on the surface of a carbon-coated aluminum foil of a current collector, and finally forming an anode plate through rolling, slitting and tabletting processes.
The remainder is the same as embodiment 1 and will not be described in detail here.
Example 9
The preparation of the negative electrode sheet was different from example 1.
And mixing the anode active material hard carbon, the conductive agent graphene, the thickener CMC, the binder PAAd and the liquid retention agent SFC according to the mass ratio of 94.3%,1.6%, 1.9%, 2.3% and 0.5% with the solvent N-methylpyrrolidone and pure water to obtain anode slurry, coating the anode slurry on the surface of the carbon-coated aluminum foil of the current collector, and finally forming the anode plate through rolling, slitting and tabletting.
The remainder is the same as embodiment 1 and will not be described in detail here.
Example 10
The preparation of the negative electrode sheet was different from example 1.
The preparation method comprises the steps of mixing the anode active substance hard carbon, the conductive agent acetylene black, the thickener CMC, the binder styrene-butadiene rubber emulsion SBR and the liquid retention agent SFC according to the mass ratio of 91.5%,1.3%, 1.7%, 3.1% and 0.3% with the solvent N-methylpyrrolidone and pure water to form anode slurry, coating the anode slurry on the surface of the carbon-coated aluminum foil of the current collector, and finally forming the anode plate through rolling, slitting and tabletting.
The remainder is the same as embodiment 1 and will not be described in detail here.
Example 11
The preparation of the negative electrode sheet was different from example 1.
The preparation method comprises the steps of mixing the anode active substance hard carbon, conductive agent carbon fiber, thickener CMC, binder styrene butadiene rubber emulsion SBR and liquid retention agent SFC with solvent N-methyl pyrrolidone and pure water according to the mass ratio of 96.0%,2.2%, 1.6%, 1.5% and 0.2% respectively to form anode slurry, coating the anode slurry on the surface of a carbon-coated aluminum foil of a current collector, and finally forming an anode plate through rolling, slitting and tabletting processes.
The remainder is the same as embodiment 1 and will not be described in detail here.
Example 12
The preparation of the negative electrode sheet was different from example 1.
And mixing the hard carbon of the anode active material, the carbon black of the conductive agent, the CMC of the thickener, the PAAd of the binder and the SFC of the liquid retention agent according to the mass ratio of 95.2%,2.2%, 1.8%, 1.5% and 0.5% with N-methylpyrrolidone serving as a solvent and pure water to form anode slurry, coating the anode slurry on the surface of a carbon-coated aluminum foil of a current collector, and finally forming the anode plate through rolling, slitting and tabletting processes.
The remainder is the same as embodiment 1 and will not be described in detail here.
The sodium ion batteries obtained in examples 1 to 4 were subjected to electrochemical performance tests, and the experimental results are shown in fig. 1 to 4.
As can be seen from fig. 1, compared with other examples, the peel strength of the negative electrode sheet of the first example was 22.3N/m, and the negative electrode sheet binder of the first example was a novel aqueous polyacrylic acid derivative binder (PAAd), which had a higher carboxyl group content than CMC, and which was capable of forming a stronger hydrogen bond with an active material having a hydroxyl group or other group on the surface, thereby promoting more uniform coating than CMC on the electrode surface. The adhesive force between the adhesive and the hard carbon particles and between the hard carbon particles and the base material can be improved, and the flexibility and the peeling strength of the pole piece are improved.
As can be seen from fig. 2, the negative electrode sheet and other embodiments of the present invention have the minimum wetting angle in the first embodiment, in which the wetting angle θ of the same electrolyte is respectively 42.1 °, 43.8 °, 45.4 ° and 53.7 °, and the smaller the wetting angle, the better the imbibition effect of the electrode sheet is, and the more beneficial the cycle life of the battery cell is. The pole piece formula is mainly beneficial to the fact that the functional polymer SFC is added in the pole piece formula, wherein the anionic macromolecules have an affinity effect with electrolyte on the surface of the pole piece, and can effectively lock the electrolyte.
As can be seen from FIG. 3, the sheet resistances of the negative electrode and other examples of the present invention are 0.96mΩ, 1.17mΩ, 1.23mΩ, and 0.98mΩ, respectively. The resistance of the pole piece surface is influenced by factors such as active materials, conductive agents, adhesives, foil materials, compaction and the like, and the smaller the resistance value is, the smaller the blocking effect on current in the charge and discharge process is. The negative electrode sheet is different from other embodiments except the binder, all other conditions are consistent, and the resistance value of the novel aqueous polyacrylic acid derivative binder (PAAd) used as the binder sheet is obviously smaller than that of other binder sheets, so that the novel aqueous polyacrylic acid derivative binder mainly benefits from the higher modulus of the acrylic acid copolymer and higher interaction force with hard carbon particles, and can effectively connect the hard carbon with the foil, and effectively reduce the sheet surface resistance.
As can be seen from FIG. 4, the capacity retention rates of the electrode sheets of the present invention for 1500 cycles of the battery are 93.40%, 90.29%, 86.66% and 83.87%, respectively. The cycle performance of the first embodiment is optimal mainly for the following two reasons: firstly, a novel aqueous polyacrylic acid derivative adhesive (PAAd) is adopted as a negative plate adhesive, so that even in the circulation process, the hard carbon particles and the base material have strong adhesive force, and a sodium storage space which is stable enough for removing sodium ions from the positive electrode can be provided; secondly, the formula of the negative electrode plate contains a functional polymer preservative SFC, and the polymer can effectively lock electrolyte on the surface of the electrode plate through intermolecular acting force so as to provide stable conditions for electronic conduction between the positive electrode and the negative electrode.
Variations and modifications of the above embodiments will occur to those skilled in the art to which the invention pertains from the foregoing disclosure and teachings. Therefore, the present invention is not limited to the above-described embodiments, but is intended to be capable of modification, substitution or variation in light thereof, which will be apparent to those skilled in the art in light of the present teachings. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present invention in any way.

Claims (10)

1. A sodium ion battery negative electrode sheet, comprising:
a negative electrode current collector;
a negative electrode active material layer coated on at least one surface of the negative electrode current collector; the negative electrode active material layer comprises the following components in percentage by weight: 90-96% of hard carbon, 1-3% of conductive agent, 1-3% of thickening agent, 1-4% of binder and 0.1-0.8% of preservative;
and the hard carbon particle diameter distribution D50 (μm), tap density A (g/cm) 3 ) And a specific surface area B (m 2 /g) satisfies the following relation:
3.0≤D50≤9.0，0.1＜A/B＜1。
2. the sodium ion battery negative electrode sheet of claim 1, wherein: the hard carbon particle size distribution D50 is more than or equal to 5.0 and less than or equal to 7.0 mu m, and the tap density A is more than or equal to 0.9g/cm 3 Specific surface area B > 2.5m 2 /g。
3. The sodium ion battery negative electrode sheet of claim 1, wherein: the conductive agent includes at least one of carbon black, acetylene black, ketjen black, carbon nanotubes, carbon fibers, and graphene.
4. The sodium ion battery negative electrode sheet of claim 1, wherein: the binder is at least one of aqueous polyacrylic acid derivative adhesive, styrene-butadiene rubber emulsion and polytetrafluoroethylene emulsion.
5. The sodium ion battery negative electrode sheet of claim 1, wherein: the thickener is sodium carboxymethyl cellulose.
6. The sodium ion battery negative electrode sheet of claim 1, wherein: the preservative is a functional polymer SFC.
7. The sodium ion battery negative electrode sheet of claim 1, wherein: the peel strength of the negative plate is D (N/m), wherein D is more than 15.0 and less than 22.5.
8. The sodium ion battery negative electrode sheet of claim 1, wherein: the surface resistance of the negative plate is E (mΩ), wherein E is more than 0.90 and less than 1.50.
9. A sodium ion battery comprising a positive plate, a negative plate, a separation membrane and electrolyte, wherein the negative plate is the sodium ion battery negative plate of any one of claims 1-7.
10. The sodium ion battery of claim 9 wherein: the wetting angle of the electrolyte is theta, wherein theta is 41 degrees less than 55 degrees.
CN202310242904.4A 2023-03-14 2023-03-14 Sodium ion battery negative plate and sodium ion battery Pending CN116314587A (en)

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Publication number Priority date Publication date Assignee Title
CN117477037A (en) * 2023-12-27 2024-01-30 溧阳中科海钠科技有限责任公司 Sodium ion battery and electric equipment
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CN113964309A (en) * 2021-11-09 2022-01-21 惠州锂威新能源科技有限公司 Negative electrode slurry and preparation method thereof, negative electrode plate and secondary battery
CN115148951A (en) * 2021-03-31 2022-10-04 宁德新能源科技有限公司 Electrochemical device and electronic device
CN115458798A (en) * 2022-09-30 2022-12-09 溧阳中科海钠科技有限责任公司 Sodium ion battery

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CN109888200A (en) * 2018-12-29 2019-06-14 深圳市卓能新能源股份有限公司 Battery cathode coating, battery cathode sheet and its manufacturing method, lithium ion battery
CN115148951A (en) * 2021-03-31 2022-10-04 宁德新能源科技有限公司 Electrochemical device and electronic device
CN113964309A (en) * 2021-11-09 2022-01-21 惠州锂威新能源科技有限公司 Negative electrode slurry and preparation method thereof, negative electrode plate and secondary battery
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CN117477037A (en) * 2023-12-27 2024-01-30 溧阳中科海钠科技有限责任公司 Sodium ion battery and electric equipment
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