CN111599984A - Positive plate, lithium ion battery comprising positive plate and preparation method of lithium ion battery - Google Patents

Positive plate, lithium ion battery comprising positive plate and preparation method of lithium ion battery Download PDF

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Publication number
CN111599984A
CN111599984A CN201910128582.4A CN201910128582A CN111599984A CN 111599984 A CN111599984 A CN 111599984A CN 201910128582 A CN201910128582 A CN 201910128582A CN 111599984 A CN111599984 A CN 111599984A
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positive
positive electrode
binder
coating
negative electrode
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李增鹏
刘成
任建国
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BTR New Material Group 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • 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
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • 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
    • 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

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  • Crystallography & Structural Chemistry (AREA)
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Abstract

The invention discloses a positive plate, a lithium ion battery comprising the positive plate and a preparation method of the lithium ion battery. The positive plate provided by the invention comprises a positive alkaline additive. The preparation method of the positive plate comprises the following steps: preparing anode slurry, wherein the anode slurry contains an anode alkaline additive, coating the anode slurry on an anode current collector, rolling, and die-cutting to obtain an anode sheet. The lithium ion battery provided by the invention comprises the positive plate. The preparation method of the lithium ion battery comprises the following steps: (1) preparing a negative plate; (2) laminating, welding, encasing and assembling the negative plate, the positive plate and the isolating membrane in the step (1) to obtain a battery cell; (3) and (3) injecting electrolyte into the battery core in the step (2), and then performing a post-treatment process to obtain the lithium ion battery. The battery provided by the invention has high energy density and good cycle performance.

Description

Positive plate, lithium ion battery comprising positive plate and preparation method of lithium ion battery
Technical Field
The invention belongs to the technical field of energy storage, relates to a pole piece, and particularly relates to a positive plate, a lithium ion battery comprising the positive plate and a preparation method of the lithium ion battery.
Background
Since the 21 st century, with the rapid development of global economy, the quality of life of people is continuously improved, and the problems of energy crisis and environmental pollution are accompanied. In such a severe situation, it has become a necessary trend to accelerate the development of new energy. With the continuous improvement and promotion of policies, the usage amount of new energy automobiles increases year by year, and as is well known, a power battery is the core of the new energy automobiles, and lithium iron phosphate power batteries are more and more favored due to better safety and long cycle life. The energy density of the existing lithium iron phosphate battery is low, and the endurance mileage of an electric automobile is seriously influenced; meanwhile, due to the reason of the lithium iron phosphate material, the conductivity of the lithium iron phosphate material is poor, the diffusion speed of lithium ions is low, the low-temperature performance is poor, and the popularization, the use and the operation of the electric automobile are seriously influenced under the condition of severe environment temperature. The commercial negative electrode material in the lithium iron phosphate lithium battery is mainly a carbon material, the theoretical specific capacity of the material is low and is about 372mAh/g, and the development of the lithium ion battery is greatly limited; the silicon-based negative electrode material has higher specific capacity, the theoretical capacity of the silicon-based material can reach more than 4200mAh/g, and the silicon-based negative electrode material has better lithium intercalation capability, and is more and more concerned by people due to the characteristic of high capacity of the material.
In order to increase the energy density of lithium iron phosphate lithium ion batteries, a great deal of research has been put into, and a corresponding effect has been achieved on the basis of, the research.
CN106450328A discloses a lithium iron phosphate battery, in which the positive electrode active material is lithium iron phosphate, the negative electrode active material is graphite, and the energy density of the battery is about 124 Wh/kg.
CN106374096A discloses a lithium iron phosphate battery, wherein the positive electrode adopts lithium iron phosphate active material, the negative electrode adopts mixture of natural graphite and mesocarbon microbeads, and the energy density of the obtained battery is about 159 Wh/kg.
CN106450436A discloses a low-temperature high-energy-density lithium iron phosphate battery, the mass percentage of each solid matter of the positive electrode is as follows: coated nanoscale lithium iron phosphate: 93.0% -95.5%; polyvinylidene fluoride: 3.5% -7.3%; oily carbon nanotubes: 1.0% -2.0%; the mass percentage of solid matters of the negative electrode is as follows: porous silicon carbon: 90.0% -93.5%; sodium carboxymethylcellulose: 1.5% -3.0%; adhesive: 3.0% -6.0%; SP type conductive carbon black: 0.5 to 1.2 percent; conductive carbon black of type C45: 0.5 to 1.5 percent; KS-6 type conductive graphite: 1.0 to 2.0 percent.
Although the above scheme can improve the cell energy density, some negative effects can be brought; under the condition of high energy density, the cycle life of the battery core can be influenced, and the electrolyte can generate chemical reaction inside the battery core to generate hydrofluoric acid, so that the effective Li can be reduced+The amount of the polymer is reduced, so that the capacity loss is caused, the stability of an SEI film is damaged, a certain attenuation or deterioration is generated on the battery cell, and the overall performance of the battery cell is influenced; therefore, the alkaline additive is added into the positive electrode to reduce the adverse effect of the positive electrode, and the battery cell environment is enabled to reach a stable system by neutralizing a certain acidic environment of the positive electrode.
In view of the above, it is desirable to provide a novel lithium ion battery to overcome the above drawbacks.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a positive plate, a lithium ion battery containing the positive plate and a preparation method of the lithium ion battery.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a positive electrode sheet including a positive electrode alkaline additive.
In the positive plate provided by the invention, the alkaline additive of the positive electrode can obviously contribute to improving the cycle performance of the battery.
The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.
According to a preferred technical scheme of the invention, the positive plate comprises a positive coating, and the positive coating comprises a positive active material and a positive alkaline additive.
Preferably, the positive electrode active material includes lithium iron phosphate.
The alkaline additive for the positive electrode comprises an inorganic additive and/or an organic additive, and is preferably a mixture of the inorganic additive and the organic additive. When the mixture of the inorganic additive and the organic additive is used, the cycle life of the battery cell can be better prolonged under the synergistic effect of the inorganic additive and the organic additive.
Preferably, the inorganic additive comprises Na2CO3、NaHCO3、K2CO3、KHCO3、Li2CO3Or LiHCO3Any one or a combination of at least two of them. Typical but non-limiting combinations are: na (Na)2CO3And NaHCO3A combination of (A), NaHCO3And K2CO3Combination of (1), K2CO3And KHCO3Combination of (1), Li2CO3And LiHCO3Combinations of (a), (b), and the like.
Preferably, the organic additive comprises any one of Hexamethyldisilazane (HMDS), heptamethyldisiminosilane (H7DMS), or lithium hexamethyldisilazide, or a combination of at least two, typically but not limited to the following combinations: a combination of hexamethyldisilazane and heptamethyldisiminoalkane, a combination of heptamethyldisiminoalkane and lithium hexamethyldisilazide, a combination of hexamethyldisilazane and lithium hexamethyldisilazide, and the like.
Preferably, the mixture of the inorganic additive and the organic additive is composed of Na2CO3And hexamethyldisilazane or a mixture ofNaHCO3And hexamethyldisilazane.
Preferably, the inorganic additive is added in an amount of 0.1 to 0.5%, for example, 0.1%, 0.2%, 0.3%, 0.4%, or 0.5% by mass of the total mass of the positive electrode active material, the conductive agent, and the binder, but the inorganic additive is not limited to the above-mentioned values, and other values not listed in the above-mentioned range are also applicable. In the invention, if the addition amount of the inorganic additive is too much, some side reactions of the electrolyte can be caused, and simultaneously, too much impurities in the additive can be introduced; if the amount of the inorganic additive added is too small, the effect of the additive is adversely affected. Within the preferable range of 0.1-0.5%, the inorganic additive can have the effects of small dosage and quick effect in the electrolyte.
Preferably, the organic additive is added in an amount of 0.1 to 0.5%, for example, 0.1%, 0.2%, 0.3%, 0.4%, or 0.5% by mass of the total mass of the positive electrode active material, the conductive agent, and the binder, but the organic additive is not limited to the above-mentioned values, and other values not listed in the above-mentioned range are also applicable. In the invention, if the addition amount of the organic additive is too much, some side reactions of the electrolyte can be caused, and simultaneously, too much impurities in the additive can be introduced; if the amount of the organic additive added is too small, the effect of the additive is adversely affected. Within the preferable range of 0.1-0.5%, the organic additive can have the effects of small dosage and quick effect in the electrolyte.
Preferably, the positive electrode active material is spherical lithium iron phosphate.
Preferably, the gram capacity of the positive electrode active material is 145 to 155mAh/g, for example, 145mAh/g, 147mAh/g, 149mAh/g, 151mAh/g, 153mAh/g, or 155mAh/g, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the particle size distribution D50 of the positive electrode active material is 0.6 to 1.6 μm, for example, D50 is 0.6 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.4 μm, or 1.6 μm, but is not limited to the values listed, and other values not listed in the numerical range are also applicable. In the invention, if the D50 of the positive active material is too large, the transmission of lithium ions can be influenced by the too large lithium iron phosphate material with smaller conductivity, and the compaction of a pole piece can be influenced by the too large lithium iron phosphate material; if the D50 of the positive electrode active material is too small, the specific surface area of the material is too large, partial agglomeration is likely to occur, and the electrical properties of the cell are affected.
Preferably, the specific surface area of the positive electrode active material is 11-15 m2G, e.g. 11m2/g、12m2/g、13m2/g、14m2G or 15m2And/g, but are not limited to, the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the positive electrode sheet further includes a positive electrode current collecting sheet for coating the positive electrode coating layer.
Preferably, the positive current collector is a carbon-coated aluminum foil.
Preferably, the positive electrode coating further comprises a conductive agent and a binder.
Preferably, the conductive agent in the positive electrode coating layer includes any one or a combination of at least two of conductive carbon black, conductive graphite, and conductive Carbon Nanotubes (CNTs), preferably a mixture of conductive carbon black, conductive graphite, and conductive carbon nanotubes. Wherein, SuperP (SP) can be selected as the conductive carbon black, and KS-6 can be selected as the conductive graphite.
Preferably, the binder in the positive electrode coating includes polyvinylidene fluoride (PVDF).
Preferably, the mass percentage of the positive electrode active material in the positive electrode coating layer is 95.5 to 96.5%, for example, 95.5%, 95.7%, 95.9%, 96.1%, 96.3%, or 96.5%, based on 100% by mass of the total of the positive electrode active material, the conductive agent, and the binder, but is not limited to the recited values, and other values not recited in the range of the values are also applicable; the conductive agent is 1.6-2.6% by mass, such as 1.6%, 1.8%, 2.0%, 2.2%, 2.4% or 2.6%, but not limited to the recited values, and other values not recited in the range of values are also applicable; the mass percentage of the binder is 1.6 to 2.2%, for example, 1.6%, 1.8%, 2.0%, or 2.2%, but is not limited to the recited values, and other values not recited in the above range are also applicable.
Preferably, when the conductive agent in the positive electrode coating is a mixture of conductive carbon black, conductive graphite and conductive carbon nanotubes, the mass ratio of the conductive carbon black to the conductive graphite to the conductive carbon nanotubes is (0.5-0.8): (0.6-1): (0.5 to 0.8), for example, 0.5:0.6:0.5, 0.6:0.7:0.6, 0.7:1:0.8, 0.8:0.8:0.7, 0.8:1:0.8, etc., but the numerical values are not limited to the enumerated values, and other numerical values not enumerated within the numerical range are also applicable.
In a second aspect, the present invention provides a method for producing a positive electrode sheet according to the first aspect, the method comprising the steps of:
preparing anode slurry, wherein the anode slurry contains an anode alkaline additive, coating the anode slurry on an anode current collector, rolling, and die-cutting to obtain the anode sheet.
As a preferred embodiment of the present invention, the method for preparing the positive electrode slurry includes: and mixing the positive active substance, the conductive agent, the binder, the positive alkaline additive and the organic solvent according to the formula ratio to obtain positive slurry.
Here, the organic solvent may be selected according to the prior art, for example, N-methylpyrrolidone (NMP) or the like is used.
Preferably, the coating is a transfer coating.
Preferably, the rolling is a counter-roll rolling.
Preferably, baking is performed prior to said rolling.
Preferably, the compaction density of the positive plate is 2.2-2.5 g/cm3E.g. 2.2g/cm3、2.2g/cm3、2.3g/cm3、2.4g/cm3Or 2.5g/cm3Etc., but are not limited to the recited values, and other values not recited within the range of the recited values are also applicable, preferably 2.3g/cm3。
Preferably, the coating surface density of the positive plate is 360-370 g/m2E.g. 360g/m2、362g/m2、364g/m2、366g/m2、368g/m2Or 370g/m2And the like, but not limited to the enumerated values, and other unrecited values within the numerical range are also applicable, and preferably 365g/m2。
In a third aspect, the present invention provides a lithium ion battery comprising the positive electrode sheet according to the first aspect.
As a preferred technical solution of the present invention, the lithium ion battery includes a positive plate, a negative plate, an isolation film for isolating the positive plate from the negative plate, and an electrolyte, the positive plate is the positive plate of the first aspect, the negative plate includes a negative electrode coating, and the negative electrode coating includes a negative electrode active material.
After the battery cell in the lithium ion battery provided by the invention is cycled for 1000 weeks, the retention rate of the battery cell can reach 85.5%, the battery cell shows better cycle performance, and the development requirement of an electric automobile can be met.
In addition, in the lithium ion battery provided by the invention, the mutual matching of the anode, the cathode and the isolating membrane plays an important role in improving the performance of the battery.
Preferably, the negative active material is a silicon-based composite material.
Preferably, the silicon-based composite material comprises a silicon oxide/carbon composite anode material (SiOx/C,0 < x < 2).
Preferably, the negative electrode active material has a gram capacity of 420 to 450mAh/g, for example, 420mAh/g, 430mAh/g, 440mAh/g, or 450mAh/g, but is not limited to the recited values, and other values not recited in the range of the recited values are also applicable.
Preferably, the particle size distribution D50 of the negative electrode active material is 14 to 18 μm, for example, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, etc., but is not limited to the values listed, and other values not listed within the range of the values are also applicable. In the present invention, if the D50 of the negative electrode active material is too large, the diffusion path of lithium ions is long, and the kinetics of the diffusion process is relatively difficult; if the D50 of the negative active material is too small, the material surface defects of the small particles are so large that the intercalated lithium ions cannot be efficiently extracted during discharge, increasing the irreversible effect.
Preferably, the specific surface area of the negative electrode active material is 1 to 2.5m2G, e.g. 1m2/g、1.2m2/g、1.4m2/g、1.6m2/g、1.8m2/g、2m2/g、2.3m2G or 2.5m2And/g, but are not limited to, the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the negative electrode sheet further comprises a negative current collector sheet for coating the negative electrode coating.
Preferably, the anode current collecting sheet is a copper foil.
Preferably, the negative electrode coating further comprises a conductive agent and a binder.
Preferably, the conductive agent in the negative electrode coating layer includes conductive carbon black. The conductive carbon black can be SuperP (SP).
Preferably, the binder in the negative electrode coating layer includes carboxymethyl cellulose (CMC) and/or styrene-butadiene rubber (SBR), preferably a mixture of carboxymethyl cellulose and styrene-butadiene rubber.
Preferably, the mass percentage of the negative electrode active material in the negative electrode coating is 94.5 to 95.5%, for example, 94.5%, 94.7%, 94.9%, 95.1%, 95.3%, or 95.5%, based on 100% by mass of the total of the negative electrode active material, the conductive agent, and the binder, but is not limited to the recited values, and other values not recited in the range of the values are also applicable; the conductive agent is 1.3 to 2% by mass, for example, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%, but not limited to the recited values, and other values not recited in the range of the values are also applicable; the mass percentage of the binder is 2.8 to 3.9%, for example, 2.8%, 3.0%, 3.1%, 3.3%, 3.5%, 3.7%, or 3.9%, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.
Preferably, when the binder in the negative electrode coating is a mixture of carboxymethyl cellulose and styrene butadiene rubber, the mass ratio of the carboxymethyl cellulose to the styrene butadiene rubber is (1-1.4): (1.8 to 2.5), for example, 1:2.5, 1:2, 1:1.8, 1.2:2.5, 1.4:2 or 1.4:1.8, etc., but not limited to the values listed, and other values not listed in the numerical range are also applicable.
In a preferred embodiment of the present invention, the separator has a porosity of 40 to 45%, for example, 40%, 41%, 42%, 43%, 44%, or 45%, but the separator is not limited to the above-mentioned values, and other values not shown in the above-mentioned numerical range are also applicable.
Preferably, the thickness of the separator is 10 to 15 μm, for example, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm, but is not limited to the values listed, and other values not listed in the range of the values are also applicable, and 12 μm is preferable.
Preferably, the electrolyte contains an organic solvent and a lithium salt.
Preferably, the organic solvent in the electrolyte solution includes Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC), and dimethyl carbonate (DMC).
Preferably, the mass ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in the electrolyte is (10-20): (60-70): (10-20), for example, 20:60:20, 15:70:15, 10:70:20, 20:65:15, 20:70:10, etc., but the electrolyte is not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the electrolyte further comprises an additive.
Preferably, the additive in the electrolyte is fluoroethylene carbonate (FEC).
Preferably, the additive is added in an amount of 5 to 10%, for example, 5%, 6%, 7%, 8%, 9%, or 10% by mass of the organic solvent based on 100% by mass of the electrolyte, but the additive is not limited to the recited values, and other values not recited in the above range are also applicable.
Preferably, the lithium salt in the electrolyte is lithium hexafluorophosphate.
Preferably, the concentration of the lithium salt in the electrolyte is 1.1 to 1.3mol/L, such as 1.1mol/L, 1.15mol/L, 1.2mol/L, 1.25mol/L, or 1.3mol/L, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
In a fourth aspect, the present invention provides a method for preparing the lithium ion battery according to the third aspect, wherein the method comprises the following steps:
(1) preparing negative electrode slurry, coating the negative electrode slurry on a negative electrode current collecting sheet, then rolling, and die-cutting to obtain a negative electrode sheet;
(2) laminating, welding, encasing and assembling the negative plate in the step (1), the positive plate in the first aspect and the isolating membrane to obtain a battery cell;
(3) and (3) injecting electrolyte into the battery core in the step (2), and then performing a post-treatment process to obtain the lithium ion battery.
The preparation method provided by the invention has the advantages of short flow, easy operation and low cost, and is suitable for industrial large-scale production.
As a preferred embodiment of the present invention, the method for preparing the negative electrode slurry in step (1) includes: and mixing the negative electrode active material, the conductive agent, the binder and the solvent according to the formula ratio to obtain negative electrode slurry.
Preferably, in step (1), the solvent comprises water.
Preferably, in step (1), the coating is transfer coating.
Preferably, in the step (1), the rolling is a roll rolling.
Preferably, in step (1), before the rolling, baking is performed.
Preferably, in the step (1), the compacted density of the negative electrode sheet is 1.5-1.7 g/cm3E.g. 1.5g/cm3、1.6g/cm3Or 1.7g/cm3Etc., but are not limited to the recited values, and other values not recited within the range of the recited values are also applicable, preferably 1.6g/cm3。
Preferably, in the step (1), the coating surface density of the negative plate is 140-150 g/m2E.g. 140g/m2、142g/m2、144g/m2、146g/m2、148g/m2Or 150g/m2Etc., but are not limited to the recited values, and other values not recited within the range of the recited values are also applicable, preferably 145g/m2。
Preferably, in the step (3), the post-treatment process comprises sealing, forming and grading.
As a further preferable technical scheme of the preparation method of the lithium ion battery, the method comprises the following steps:
(1) mixing the positive active material lithium iron phosphate, a conductive agent, a binder and an organic solvent according to the formula ratio, adding a positive alkaline additive into the obtained mixed solution to obtain positive slurry, coating the positive slurry on a positive current collecting sheet by transfer coating, baking, rolling by a pair of rollers, and die-cutting to obtain the lithium iron phosphate with the compacted density of 2.3g/cm3The coating surface density is 365g/m2The positive electrode sheet of (1);
wherein the conductive agent is a mixture of conductive carbon black, conductive graphite and conductive carbon nanotubes, and the binder is polyvinylidene fluoride; the mass percent of the positive active substance is 95.5-96.5%, the mass percent of the conductive agent is 1.6-2.6%, and the mass percent of the binder is 1.6-2.2% based on 100% of the total mass of the positive active substance, the conductive agent and the binder; the mass ratio of the conductive carbon black to the conductive graphite to the conductive carbon nano tube is (0.5-0.8): (0.6-1): (0.5 to 0.8); the positive electrode alkaline additive is a mixture of an inorganic additive and an organic additive, the addition amount of the inorganic additive is 0.1-0.5% of the total mass of the positive electrode active substance, the conductive agent and the binder, and the addition amount of the organic additive is 0.1-0.5% of the total mass of the positive electrode active substance, the conductive agent and the binder;
(2) mixing the negative active material, the conductive agent, the binder and the solvent according to the formula ratio to obtain negative slurry, coating the negative slurry on a negative current collector by transfer coating, baking, rolling by a pair of rollers, and die-cutting to obtain the compact density of 1.6g/cm3The coating surface density is 145g/m2The negative electrode sheet of (1);
the negative active substance is a silicon oxide/carbon composite material, the conductive agent is conductive carbon black, and the binder is a mixture of carboxymethyl cellulose and styrene butadiene rubber; the mass percent of the negative electrode active material is 94.5-95.5%, the mass percent of the conductive agent is 1.3-2%, and the mass percent of the binder is 2.8-3.9% by taking the total mass of the negative electrode active material, the conductive agent and the binder as 100%; the mass ratio of the carboxymethyl cellulose to the styrene butadiene rubber is (1-1.4): (1.8-2.5);
(3) laminating, welding, entering a shell and assembling the positive plate in the step (1), the negative plate in the step (2) and the isolating membrane to obtain a battery cell;
(4) and (4) injecting the electrolyte into the battery cell in the step (3), and then sealing, forming and grading to obtain the lithium ion battery.
In the above further preferred technical scheme, the positive active material lithium iron phosphate, the negative active material silicon oxide/carbon composite material and the positive alkaline additive are matched with each other, which greatly helps to improve the energy density and cycle life of the battery.
Compared with the prior art, the invention has the following beneficial effects:
(1) the alkaline additive is added into the positive plate provided by the invention, so that the cycle performance of the battery can be obviously improved.
(2) The lithium ion battery provided by the invention has the advantages that the main materials of the battery, such as the positive plate, the negative plate, the isolating membrane, the electrolyte and the like, are optimized, so that the positive plate, the negative plate, the isolating membrane, the electrolyte and the like are better matched with each other, the obtained lithium ion battery has higher energy density, and the battery core shows better cycle performance. According to the invention, when the inorganic additive and the organic additive are simultaneously added into the positive electrode, the cycle life of the battery cell can be better prolonged under the synergistic effect of the inorganic additive and the organic additive. The energy density of the lithium ion battery provided by the invention can reach more than 180Wh/kg, and the cycle retention rate after 1000 cycles can reach 85.5%. According to the invention, when the additive is added into the electrolyte, the low-temperature performance of the battery cell can be better improved.
(3) The preparation method of the positive plate and the preparation method of the lithium ion battery provided by the invention have the advantages of short flow, easiness in operation and low cost, and are suitable for industrial large-scale production.
Drawings
Fig. 1 is an SEM image of a spherical lithium iron phosphate material used in example 1 of the present invention;
FIG. 2 is an SEM photograph of a silica/carbon composite material used in example 1 of the present invention.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
The following are typical but non-limiting examples of the invention:
example 1
The present embodiment provides a positive electrode sheet and a lithium ion battery, the battery including: the lithium battery comprises a positive plate, a negative plate, a separation film for separating the positive plate from the negative plate and electrolyte.
The positive plate comprises a positive current collecting plate and a positive coating coated on the positive current collecting plate, wherein the positive coating comprises a positive active substance, a positive alkaline additive, a conductive agent and a binder. The positive electrode active material is spherical lithium iron phosphate, the conductive agent is a mixture of conductive carbon black, conductive graphite and conductive carbon nanotubes, and the binder is polyvinylidene fluoride. The mass percent of the positive electrode active substance is 95.5%, the mass percent of the conductive agent is 2.3%, and the mass percent of the binder is 2.2%, wherein the total mass of the positive electrode active substance, the conductive agent and the binder is 100%; the mass ratio of the conductive carbon black to the conductive graphite to the conductive carbon nanotube is 0.8: 1.0: 0.5. the alkaline additive of the positive electrode is Na2CO3And hexamethyldisilazane-based lithium salt, based on 100% by mass of the total of the positive electrode active material, the conductive agent and the binder, and Na2CO3The amount of (B) was 0.1%, and the amount of hexamethyldisilazane-based lithium was 0.2%. The positive collector is a carbon-coated aluminum foil. The gram capacity of the positive active material is 150mAh/g, and the particle size distribution is D501.0 μm, a specific surface area of 13m2/g。
Fig. 1 is an SEM image of a spherical lithium iron phosphate material used as a positive electrode active material in the present example, and it can be seen from the SEM image that the material exhibits a spherical morphology and is well dispersed, and the material is composed of a spherical group of large and small particles.
The negative plate comprises a negative current collecting plate and a negative coating coated on the negative current collecting plate, the negative coating comprises a negative active material, a conductive agent and a binder, the negative active material is a silicon oxide/carbon composite material, the conductive agent is conductive carbon black, and the binder is a mixture of carboxymethyl cellulose and styrene butadiene rubber. The mass percent of the negative electrode active material is 94.5%, the mass percent of the conductive agent is 2%, and the mass percent of the binder is 3.5%, wherein the total mass of the negative electrode active material, the conductive agent and the binder is 100%; the mass ratio of the carboxymethyl cellulose to the styrene-butadiene rubber is 1: 2.5. the negative current collector is a copper foil. The negative electrode active material had a gram capacity of 435mAh/g, a particle size distribution D50 of 16 μm, and a specific surface area of 2m2/g。
Fig. 2 is an SEM image of the silica/carbon composite material used as the negative electrode active material in the present example, and it can be seen from the image that the material is distributed in a lump form and the particle surface is smooth.
The separator had a porosity of 43%, a width of 112mm and a film thickness of 12 μm.
The electrolyte is composed of an organic solvent, an additive and a lithium salt, wherein the organic solvent is prepared from the following components in percentage by mass: 65:15, the additive is fluoroethylene carbonate, the addition amount of the additive is 5 percent based on 100 percent of the mass of the organic solvent, and the lithium hexafluorophosphate with the lithium salt concentration of 1.2mol/L is added.
The embodiment also provides a preparation method of the positive plate, which comprises the following steps:
mixing the positive active material lithium iron phosphate, a conductive agent, a binder and an organic solvent according to the formula ratio, adding a positive alkaline additive into the obtained mixed solution to obtain positive slurry,coating the positive electrode slurry on a positive electrode current collector by using transfer coating, baking, pressing the positive electrode slurry to perform double-roller rolling on the positive electrode, and finally performing die cutting according to the size of the positive electrode to obtain the positive electrode slurry with the compacted density of 2.3g/cm3The coating surface density is 365g/m2The positive electrode sheet of (1).
The embodiment also provides a preparation method of the lithium ion battery, which comprises the following steps:
(1) preparing a positive plate according to the method provided by the embodiment;
(2) mixing the negative active substance, the conductive agent, the binder and water according to the formula ratio to obtain negative slurry, coating the negative slurry on a negative current collector by transfer coating, baking, pressing to compact the density to roll the pole piece, and finally performing die cutting according to the size of the pole piece to obtain the compact density of 1.6g/cm3The coating surface density is 145g/m2The negative electrode sheet of (1);
(3) laminating, welding, entering a shell and assembling the positive plate provided by the implementation, the negative plate in the step (2) and the isolating membrane to obtain a battery cell;
(4) and (4) injecting the electrolyte into the battery cell in the step (3), and then sealing, forming and grading to obtain the lithium ion battery.
The lithium ion battery obtained in the embodiment is subjected to electrochemical performance experimental test, and the test method comprises the following steps:
and (3) capacity testing: the test cabinet produced by Ningbo Baote test and control technology company Limited is used, the battery capacity is 1C current discharge capacity, and the voltage range is 2.0-3.65V;
testing the internal resistance of the battery core: testing and reading by using an internal resistance meter in Guangzhou Optimus; the cell is recycled by using a test cabinet produced by Ningbo Baote measurement and control technology company Limited, and the test cabinet is carried out under the condition of 1C/1C charging and discharging test, and the voltage range is 2.0-3.65V.
The test results are shown in table 1.
The lithium ion battery obtained in the embodiment was subjected to a 0.5C discharge test at-20 ℃, the test method was a test cabinet produced by Ningbo Tech test and control technologies, Inc., the cell was subjected to a charge and discharge test at a current of 0.5C, the voltage range was 2.0-3.65V, and the discharge cutoff current was 0.02C. The test results are shown in table 2.
Example 2
The specific material and structure of the positive electrode sheet provided in this example refer to example 1, except that in the positive electrode coating, the positive electrode alkaline additive is NaHCO3And hexamethyldisilazane, wherein the total mass of the positive electrode active material, the conductive agent and the binder is 100%3The amount of (A) was 0.2% and the amount of hexamethyldisilazane was 0.3%.
In addition to the above differences, the positive electrode sheet production method of this example refers to example 1.
The lithium ion battery of the present embodiment adopts the above positive electrode sheet, and the other specific materials and structures and the method for manufacturing the lithium ion battery refer to embodiment 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 3
The specific material and structure of the positive electrode sheet provided in this example refer to example 1, except that in the positive electrode coating layer, the positive electrode alkaline additive is only NaHCO3NaHCO, based on 100% of the total mass of the positive electrode active material, the conductive agent and the binder3The amount of (B) added was 0.1%.
In addition to the above differences, the positive electrode sheet production method of this example refers to example 1.
The lithium ion battery of the present embodiment adopts the above positive electrode sheet, and the other specific materials and structures and the method for manufacturing the lithium ion battery refer to embodiment 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 4
The specific material and structure of the positive electrode sheet provided in this example are as in example 1, except that in the positive electrode coating layer, the positive electrode alkaline additive is only heptamethyldisiminoalkane, and the amount of heptamethyldisiminoalkane added is 0.2% based on 100% by mass of the total of the positive electrode active material, the conductive agent, and the binder.
In addition to the above differences, the positive electrode sheet production method of this example refers to example 1.
The lithium ion battery of the present embodiment adopts the above positive electrode sheet, and the other specific materials and structures and the method for manufacturing the lithium ion battery refer to embodiment 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 5
The present embodiment provides a positive electrode sheet and a lithium ion battery, the battery including: comprises a positive plate, a negative plate, an isolating film for isolating the positive plate and the negative plate and electrolyte.
The positive plate comprises a positive current collecting plate and a positive coating coated on the positive current collecting plate, wherein the positive coating comprises a positive active substance, a positive alkaline additive, a conductive agent and a binder. The positive electrode active material is spherical lithium iron phosphate, the conductive agent is a mixture of conductive carbon black, conductive graphite and conductive carbon nanotubes, and the binder is polyvinylidene fluoride. The mass percent of the positive electrode active substance is 96.5%, the mass percent of the conductive agent is 1.6%, and the mass percent of the binder is 1.9% based on 100% of the total mass of the positive electrode active substance, the conductive agent and the binder; the mass ratio of the conductive carbon black to the conductive graphite to the conductive carbon nanotube is 0.5:0.6: 0.8. the alkaline additive of the positive electrode is Na2CO3And hexamethyldisilazane-based lithium salt, based on 100% by mass of the total of the positive electrode active material, the conductive agent and the binder, and Na2CO3The amount of (B) was 0.1%, and the amount of hexamethyldisilazane-based lithium was 0.1%. The positive collector is a carbon-coated aluminum foil. The gram capacity of the positive electrode active material was 145mAh/g, the particle size distribution D50 was 0.6. mu.m, and the specific surface area was 15m2/g。
The above-mentionedThe negative plate comprises a negative current collecting plate and a negative coating coated on the negative current collecting plate, the negative coating comprises a negative active material, a conductive agent and a binder, the negative active material is a silicon oxide/carbon composite material, the conductive agent is conductive carbon black, and the binder is a mixture of carboxymethyl cellulose and styrene butadiene rubber. The mass percent of the negative electrode active material is 94.8%, the mass percent of the conductive agent is 1.3%, and the mass percent of the binder is 3.9% based on the total mass of the negative electrode active material, the conductive agent and the binder being 100%; the mass ratio of the carboxymethyl cellulose to the styrene-butadiene rubber is 1.2:2. the negative current collector is a copper foil. The negative electrode active material had a gram volume of 420mAh/g, a particle size distribution D50 of 18 μm, and a specific surface area of 1m2/g。
The porosity of the separator was 40%, the width was 112mm, and the film thickness was 10 μm.
The electrolyte is composed of an organic solvent, an additive and a lithium salt, wherein the organic solvent is prepared from the following components in a mass ratio of 10:70: 10 of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, wherein the additive is fluoroethylene carbonate, the addition amount of the additive is 5 percent based on 100 percent of the mass of the organic solvent, and the lithium hexafluorophosphate with the lithium salt concentration of 1.1mol/L is adopted.
The embodiment also provides a preparation method of the positive plate, which comprises the following steps:
mixing the positive active material lithium iron phosphate, a conductive agent, a binder and an organic solvent according to the formula ratio, adding a positive alkaline additive into the obtained mixed solution to obtain positive slurry, coating the positive slurry on a positive current collector by transfer coating, baking, pressing the positive current collector to roll the positive current collector according to the compaction density, and finally performing die cutting according to the size of the positive current collector to obtain the positive current collector with the compaction density of 2.2g/cm3The coating surface density is 360g/m2The positive electrode sheet of (1).
The embodiment also provides a preparation method of the lithium ion battery, which comprises the following steps:
(1) preparing a positive plate according to the method provided by the embodiment;
(2) the formula amountMixing the negative active substance, the conductive agent, the binder and water to obtain negative slurry, coating the negative slurry on a negative current collector by transfer coating, baking, pressing to compact density, rolling the pole piece by a pair of rollers, and finally die-cutting according to the size of the pole piece to obtain the compact density of 1.5g/cm3The coating surface density is 140g/m2The negative electrode sheet of (1);
(3) laminating, welding, entering a shell and assembling the positive plate in the step (1), the negative plate in the step (2) and the isolating membrane to obtain a battery cell;
(4) and (4) injecting the electrolyte into the battery cell in the step (3), and then sealing, forming and grading to obtain the lithium ion battery.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 6
The present embodiment provides a positive electrode sheet and a lithium ion battery, the battery including: comprises a positive plate, a negative plate, an isolating film for isolating the positive plate and the negative plate and electrolyte.
The positive plate comprises a positive current collecting plate and a positive coating coated on the positive current collecting plate, wherein the positive coating comprises a positive active substance, a positive alkaline additive, a conductive agent and a binder. The positive electrode active material is spherical lithium iron phosphate, the conductive agent is a mixture of conductive carbon black, conductive graphite and conductive carbon nanotubes, and the binder is polyvinylidene fluoride. The mass percent of the positive electrode active substance is 95.8%, the mass percent of the conductive agent is 2.6%, and the mass percent of the binder is 1.6% based on 100% of the total mass of the positive electrode active substance, the conductive agent and the binder; the mass ratio of the conductive carbon black, the conductive graphite and the conductive carbon nano tube is 0.6: 0.9: 0.7. the alkaline additive of the positive electrode is Na2CO3And hexamethyldisilazane-based lithium salt, based on 100% by mass of the total of the positive electrode active material, the conductive agent and the binder, and Na2CO30.5% of (B) and hexamethyldisilazaneThe amount of lithium added was 0.5%. The positive collector is a carbon-coated aluminum foil. The gram capacity of the positive electrode active material was 155mAh/g, the particle size distribution D50 was 1.6. mu.m, and the specific surface area was 11m2/g。
The negative plate comprises a negative current collecting plate and a negative coating coated on the negative current collecting plate, the negative coating comprises a negative active material, a conductive agent and a binder, the negative active material is a silicon oxide/carbon composite material, the conductive agent is conductive carbon black, and the binder is a mixture of carboxymethyl cellulose and styrene butadiene rubber. The mass percent of the negative electrode active material is 95.5%, the mass percent of the conductive agent is 1.7%, and the mass percent of the binder is 2.8% based on 100% of the total mass of the negative electrode active material, the conductive agent and the binder; the mass ratio of the carboxymethyl cellulose to the styrene-butadiene rubber is 1.4: 1.8. the negative current collector is a copper foil. The negative electrode active material had a gram volume of 450mAh/g, a particle size distribution D50 of 14 μm, and a specific surface area of 2.5m2/g。
The porosity of the separator was 45%, the width was 112mm, and the film thickness was 15 μm.
The electrolyte is composed of an organic solvent, an additive and a lithium salt, wherein the organic solvent is prepared from the following components in a mass ratio of 20:60:20 of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, wherein the additive is fluoroethylene carbonate, the addition amount of the additive is 10 percent based on 100 percent of the mass of the organic solvent, and the lithium hexafluorophosphate with the lithium salt concentration of 1.3mol/L is adopted.
The embodiment also provides a preparation method of the positive plate, which comprises the following steps:
mixing the positive active material lithium iron phosphate, a conductive agent, a binder and an organic solvent according to the formula ratio, adding a positive alkaline additive into the obtained mixed solution to obtain positive slurry, coating the positive slurry on a positive current collector by transfer coating, baking, pressing the positive current collector to roll the positive current collector according to the compaction density, and finally die-cutting according to the size of the positive current collector to obtain the positive current collector with the compaction density of 2.5g/cm3The coating surface density is 370g/m2The positive electrode sheet of (1).
The embodiment also provides a preparation method of the lithium ion battery, which comprises the following steps:
(1) preparing a positive plate according to the method provided by the embodiment;
(2) mixing the negative active substance, the conductive agent, the binder and water according to the formula ratio to obtain negative slurry, coating the negative slurry on a negative current collector by transfer coating, baking, pressing to compact the density to roll the pole piece, and finally performing die cutting according to the size of the pole piece to obtain the compact density of 1.7g/cm3The coating surface density is 150g/m2The negative electrode sheet of (1);
(3) laminating, welding, entering a shell and assembling the positive plate in the step (1), the negative plate in the step (2) and the isolating membrane to obtain a battery cell;
(4) and (4) injecting the electrolyte into the battery cell in the step (3), and then sealing, forming and grading to obtain the lithium ion battery.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 7
Specific materials and structures of positive electrode sheets provided in this example referring to example 1, the difference is that in the positive electrode coating layer, Na is present in an amount of 100% by mass of the total of the positive electrode active material, the conductive agent and the binder2CO3The amount of (B) was 0.03%, and the amount of hexamethyldisilazane-based lithium was 0.2%.
In addition to the above differences, the positive electrode sheet production method of this example refers to example 1.
The lithium ion battery of the present embodiment adopts the above positive electrode sheet, and the other specific materials and structures and the method for manufacturing the lithium ion battery refer to embodiment 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 8
The embodiment provides the specific structure of the positive plateMaterials and structures referring to example 1, except that in the positive electrode coating layer, Na was contained in an amount of 100% by mass of the total of the positive electrode active material, the conductive agent and the binder2CO3The amount of (B) was 5% and the amount of hexamethyldisilazane-based lithium was 0.2%.
In addition to the above differences, the positive electrode sheet production method of this example refers to example 1.
The lithium ion battery of the present embodiment adopts the above positive electrode sheet, and the other specific materials and structures and the method for manufacturing the lithium ion battery refer to embodiment 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 9
Specific materials and structures of positive electrode sheets provided in this example referring to example 1, the difference is that in the positive electrode coating layer, Na is present in an amount of 100% by mass of the total of the positive electrode active material, the conductive agent and the binder2CO3The amount of (B) was 0.1%, and the amount of hexamethyldisilazane-based lithium was 0.03%.
In addition to the above differences, the positive electrode sheet production method of this example refers to example 1.
The lithium ion battery of the present embodiment adopts the above positive electrode sheet, and the other specific materials and structures and the method for manufacturing the lithium ion battery refer to embodiment 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 10
Specific materials and structures of positive electrode sheets provided in this example referring to example 1, the difference is that in the positive electrode coating layer, Na is present in an amount of 100% by mass of the total of the positive electrode active material, the conductive agent and the binder2CO3The amount of (B) was 0.1%, and the amount of hexamethyldisilazane-based lithium was 5%.
In addition to the above differences, the positive electrode sheet production method of this example refers to example 1.
The lithium ion battery of the present embodiment adopts the above positive electrode sheet, and the other specific materials and structures and the method for manufacturing the lithium ion battery refer to embodiment 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 11
Specific materials and structures of the positive electrode sheet provided in this example refer to example 1, except that the particle size distribution D50 of the positive electrode active material in the positive electrode coating layer was 0.2 μm.
In addition to the above differences, the positive electrode sheet production method of this example refers to example 1.
The lithium ion battery of the present embodiment adopts the above positive electrode sheet, and the other specific materials and structures and the method for manufacturing the lithium ion battery refer to embodiment 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 12
Specific materials and structures of the positive electrode sheet provided in this example refer to example 1, except that the particle size distribution D50 of the positive electrode active material in the positive electrode coating layer was 5 μm.
In addition to the above differences, the positive electrode sheet production method of this example refers to example 1.
The lithium ion battery of the present embodiment adopts the above positive electrode sheet, and the other specific materials and structures and the method for manufacturing the lithium ion battery refer to embodiment 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 13
The lithium ion battery provided in this example was specifically structured as described in example 1, except that the particle size distribution D50 of the negative electrode active material in the negative electrode coating was 8 μm.
The lithium ion battery of this example was prepared by the method described in example 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Example 14
The lithium ion battery provided in this example was specifically structured as described in example 1, except that the particle size distribution D50 of the negative electrode active material in the negative electrode coating was 25 μm.
The lithium ion battery of this example was prepared by the method described in example 1.
The lithium ion battery obtained in this example was tested according to the method of example 1, and the electrochemical performance test results are shown in table 1, and the 0.5C discharge test results at-20 ℃ are shown in table 2.
Comparative example 1
The specific material and structure of the lithium ion battery provided in this example are as described in example 1, except that no alkaline additive is added to the positive electrode coating.
The lithium ion battery of this comparative example was prepared according to example 1.
The lithium ion battery obtained in the present comparative example was tested according to the method of example 1, and the results of the electrochemical performance test are shown in table 1, and the results of the 0.5C discharge test at-20 ℃ are shown in table 2.
TABLE 1 lithium ion Battery electrochemical Performance data
Figure BDA0001974446000000231
Figure BDA0001974446000000241
TABLE 2 discharge data of Li-ion battery at-20 deg.C
Figure BDA0001974446000000242
The lithium ion batteries obtained in the embodiments 1 and 2 of the invention have the best performance and the energy density can reach over 180Wh/kg, which can show that the lithium iron phosphate batteries have better energy density; the lithium iron phosphate battery has high cycle retention rate after multiple cycles, and has better retention rate under the condition of low-temperature-20 ℃ discharge, which can show that the lithium iron phosphate battery has better low-temperature discharge performance. The batteries of examples 5 and 6 also exhibited excellent performance.
Examples 3 and 4 have a reduced cycle retention compared to examples 1 and 2 because the preferred mixture of inorganic and organic additives is not used as the positive electrode alkaline additive, but only the inorganic additive (example 3) or the organic additive (example 4) is used. Comparative example 1 the positive electrode alkaline additive was not used at all, and thus the cycle retention was the worst.
Although the alkaline additives of the positive electrodes of examples 7 to 10 are a mixture of an inorganic additive and an organic additive, the performance (particularly, cycle performance) of the battery is reduced to some extent when the inorganic additive of example 7 is excessively added, the inorganic additive of example 8 is excessively added, the organic additive of example 9 is excessively added, and the organic additive of example 10 is excessively added.
The positive electrode active material D50 in example 11 was too small, the positive electrode active material D50 in example 12 was too large, the negative electrode active material D50 in example 13 was too small, and the negative electrode active material D50 in example 14 was too large, all of which adversely affected the battery performance to some extent.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims (10)

1. The positive plate is characterized by comprising a positive alkaline additive.
2. The positive electrode sheet according to claim 1, wherein the positive electrode sheet comprises a positive electrode coating layer comprising a positive electrode active material and a positive electrode alkaline additive;
preferably, the positive electrode active material includes lithium iron phosphate;
the positive electrode alkaline additive comprises an inorganic additive and/or an organic additive, and is preferably a mixture of the inorganic additive and the organic additive;
preferably, the inorganic additive comprises Na2CO3、NaHCO3、K2CO3、KHCO3、Li2CO3Or LiHCO3Any one or a combination of at least two of;
preferably, the organic additive comprises any one of hexamethyldisilazane, heptamethyldisiminosilane or lithium hexamethyldisilazide or a combination of at least two of the hexamethyldisilazane and the heptamethyldisiminosilane;
preferably, the mixture of the inorganic additive and the organic additive is composed of Na2CO3And hexamethyldisilazane or from NaHCO3And hexamethyldisilazane;
preferably, the addition amount of the inorganic additive is 0.1-0.5% of the total mass of the positive electrode active material, the conductive agent and the binder;
preferably, the addition amount of the organic additive is 0.1-0.5% of the total mass of the positive electrode active material, the conductive agent and the binder;
preferably, the positive electrode active material is spherical lithium iron phosphate;
preferably, the gram capacity of the positive active material is 145-155 mAh/g;
preferably, the particle size distribution D50 of the positive electrode active material is 0.6-1.6 μm;
preferably, the specific surface area of the positive electrode active material is 11-15 m2/g；
Preferably, the positive electrode sheet further comprises a positive current collecting sheet for coating the positive coating;
preferably, the positive collector is a carbon-coated aluminum foil;
preferably, the positive electrode coating further comprises a conductive agent and a binder;
preferably, the conductive agent in the positive electrode coating comprises any one or a combination of at least two of conductive carbon black, conductive graphite and conductive carbon nanotubes, preferably a mixture of conductive carbon black, conductive graphite and conductive carbon nanotubes;
preferably, the binder in the positive electrode coating layer comprises polyvinylidene fluoride;
preferably, in the positive electrode coating, the mass percent of the positive electrode active substance is 95.5-96.5%, the mass percent of the conductive agent is 1.6-2.6%, and the mass percent of the binder is 1.6-2.2%, based on 100% of the total mass of the positive electrode active substance, the conductive agent and the binder;
preferably, when the conductive agent in the positive electrode coating is a mixture of conductive carbon black, conductive graphite and conductive carbon nanotubes, the mass ratio of the conductive carbon black to the conductive graphite to the conductive carbon nanotubes is (0.5-0.8): (0.6-1): (0.5-0.8).
3. A method for producing the positive electrode sheet according to claim 1, comprising the steps of:
preparing anode slurry, wherein the anode slurry contains an anode alkaline additive, coating the anode slurry on an anode current collector, rolling, and die-cutting to obtain the anode sheet.
4. The method for producing a positive electrode sheet according to claim 3, wherein the method for producing a positive electrode slurry comprises: mixing the positive active substance, the conductive agent, the binder, the positive alkaline additive and the organic solvent according to the formula ratio to obtain positive slurry;
preferably, the coating is a transfer coating;
preferably, the rolling is double-roll rolling;
preferably, before said rolling, baking is carried out;
preferably, the compaction density of the positive plate is 2.2-2.5 g/cm3Preferably 2.3g/cm3；
Preferably, the coating surface density of the positive plate is 360-370 g/m2Preferably 365g/m2。
5. A lithium ion battery comprising the positive electrode sheet according to claim 1 or 2.
6. The lithium ion battery according to claim 5, wherein the lithium ion battery comprises a positive electrode sheet, a negative electrode sheet, a separator for separating the positive electrode sheet from the negative electrode sheet, and an electrolyte, wherein the positive electrode sheet is the positive electrode sheet according to claim 1 or 2, the negative electrode sheet comprises a negative electrode coating layer, and the negative electrode coating layer comprises a negative electrode active material;
preferably, the negative active material is a silicon-based composite material;
preferably, the silicon-based composite material comprises a silica/carbon composite anode material;
preferably, the gram capacity of the negative electrode active material is 420-450 mAh/g;
preferably, the particle size distribution D50 of the negative electrode active material is 14-18 μm;
preferably, the specific surface area of the negative electrode active material is 1 to 2.5m2/g；
Preferably, the negative electrode sheet further comprises a negative current collector sheet for coating the negative electrode coating;
preferably, the negative current collector is a copper foil;
preferably, the negative electrode coating further comprises a conductive agent and a binder;
preferably, the conductive agent in the negative electrode coating layer includes conductive carbon black;
preferably, the binder in the negative electrode coating comprises carboxymethyl cellulose and/or styrene-butadiene rubber, preferably a mixture of carboxymethyl cellulose and styrene-butadiene rubber;
preferably, in the negative electrode coating, the mass percent of the negative electrode active material is 94.5-95.5%, the mass percent of the conductive agent is 1.3-2%, and the mass percent of the binder is 2.8-3.9% based on 100% of the total mass of the negative electrode active material, the conductive agent and the binder;
preferably, when the binder in the negative electrode coating is a mixture of carboxymethyl cellulose and styrene butadiene rubber, the mass ratio of the carboxymethyl cellulose to the styrene butadiene rubber is (1-1.4): (1.8-2.5).
7. The lithium ion battery according to claim 5 or 6, wherein the porosity of the separator is 40-45%;
preferably, the thickness of the isolation film is 10-15 μm, preferably 12 μm;
preferably, the electrolyte comprises an organic solvent and a lithium salt;
preferably, the organic solvent in the electrolyte comprises ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate;
preferably, in the electrolyte, the mass ratio of the ethylene carbonate to the dimethyl carbonate to the ethyl methyl carbonate is (10-20): 60-70): 10-20;
preferably, the electrolyte further comprises an additive;
preferably, the additive in the electrolyte is fluoroethylene carbonate;
preferably, in the electrolyte, the addition amount of the additive is 5-10% by mass of the organic solvent as 100%;
preferably, the lithium salt in the electrolyte is lithium hexafluorophosphate;
preferably, the concentration of the lithium salt in the electrolyte is 1.1-1.3 mol/L.
8. A method for preparing a lithium ion battery according to any of claims 5 to 7, characterized in that the method comprises the following steps:
(1) preparing negative electrode slurry, coating the negative electrode slurry on a negative electrode current collecting sheet, then rolling, and die-cutting to obtain a negative electrode sheet;
(2) laminating, welding, encasing and assembling the negative plate in the step (1), the positive plate in the claim 1 or 2 and the isolating membrane to obtain a battery cell;
(3) and (3) injecting electrolyte into the battery core in the step (2), and then performing a post-treatment process to obtain the lithium ion battery.
9. The method for preparing a lithium ion battery according to claim 8, wherein the method for preparing the negative electrode slurry according to the step (1) comprises: mixing the negative electrode active material, the conductive agent, the binder and the solvent according to the formula ratio to obtain negative electrode slurry;
preferably, in step (1), the solvent comprises water;
preferably, in step (1), the coating is transfer coating;
preferably, in the step (1), the rolling is a double-roll rolling;
preferably, in step (1), before the rolling, baking is performed;
preferably, in the step (1), the compacted density of the negative electrode sheet is 1.5-1.7 g/cm3Preferably 1.6g/cm3；
Preferably, in the step (1), the coating surface density of the negative plate is 140-150 g/m2Preferably 145g/m2；
Preferably, in the step (3), the post-treatment process comprises sealing, forming and grading.
10. Method for preparing a lithium-ion battery according to claim 8 or 9, characterized in that it comprises the following steps:
(1) mixing the positive active material lithium iron phosphate, a conductive agent, a binder and an organic solvent according to the formula ratio, adding a positive alkaline additive into the obtained mixed solution to obtain positive slurry, coating the positive slurry on a positive current collecting sheet by transfer coating, and carrying out the steps ofAfter baking, the mixture is rolled by a pair of rollers, and the compacted density of the mixture is 2.3g/cm after die cutting3The coating surface density is 365g/m2The positive electrode sheet of (1);
wherein the conductive agent is a mixture of conductive carbon black, conductive graphite and conductive carbon nanotubes, and the binder is polyvinylidene fluoride; the mass percent of the positive active substance is 95.5-96.5%, the mass percent of the conductive agent is 1.6-2.6%, and the mass percent of the binder is 1.6-2.2% based on 100% of the total mass of the positive active substance, the conductive agent and the binder; the mass ratio of the conductive carbon black to the conductive graphite to the conductive carbon nano tube is (0.5-0.8): (0.6-1): (0.5 to 0.8); the positive electrode alkaline additive is a mixture of an inorganic additive and an organic additive, the addition amount of the inorganic additive is 0.1-0.5% of the total mass of the positive electrode active substance, the conductive agent and the binder, and the addition amount of the organic additive is 0.1-0.5% of the total mass of the positive electrode active substance, the conductive agent and the binder;
(2) mixing the negative active material, the conductive agent, the binder and the solvent according to the formula ratio to obtain negative slurry, coating the negative slurry on a negative current collector by transfer coating, baking, rolling by a pair of rollers, and die-cutting to obtain the compact density of 1.6g/cm3The coating surface density is 145g/m2The negative electrode sheet of (1);
the negative active substance is a silicon oxide/carbon composite material, the conductive agent is conductive carbon black, and the binder is a mixture of carboxymethyl cellulose and styrene butadiene rubber; the mass percent of the negative electrode active material is 94.5-95.5%, the mass percent of the conductive agent is 1.3-2%, and the mass percent of the binder is 2.8-3.9% by taking the total mass of the negative electrode active material, the conductive agent and the binder as 100%; the mass ratio of the carboxymethyl cellulose to the styrene butadiene rubber is (1-1.4): (1.8-2.5);
(3) laminating, welding, entering a shell and assembling the positive plate in the step (1), the negative plate in the step (2) and the isolating membrane to obtain a battery cell;
(4) and (4) injecting the electrolyte into the battery cell in the step (3), and then sealing, forming and grading to obtain the lithium ion battery.
CN201910128582.4A 2019-02-21 2019-02-21 Positive plate, lithium ion battery comprising positive plate and preparation method of lithium ion battery Pending CN111599984A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112054202A (en) * 2020-09-10 2020-12-08 辽宁九夷锂能股份有限公司 High-energy high-rate lithium battery positive electrode additive, preparation method thereof and positive plate containing positive electrode additive
CN112151755A (en) * 2020-09-08 2020-12-29 江苏塔菲尔新能源科技股份有限公司 Positive plate and battery
CN112864346A (en) * 2021-01-12 2021-05-28 惠州亿纬锂能股份有限公司 Pole piece, preparation method thereof and battery
CN115498246A (en) * 2022-09-22 2022-12-20 江苏正力新能电池技术有限公司 Lithium ion battery, battery module and battery pack
CN115579507A (en) * 2022-10-21 2023-01-06 江苏正力新能电池技术有限公司 Secondary battery and preparation method thereof, battery pack and power utilization device
WO2023133798A1 (en) * 2022-01-14 2023-07-20 宁德时代新能源科技股份有限公司 Positive electrode composite material for lithium-ion secondary battery, positive electrode, and battery
US11817578B2 (en) * 2019-06-05 2023-11-14 Enevate Corporation Silicon-based energy storage devices with silyl amine compounds or derivatives of silyl amine containing electrolyte additives

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5846673A (en) * 1996-12-09 1998-12-08 Valence Technology, Inc. Additive to stabilize electrochemical cell
US20100015523A1 (en) * 2006-08-21 2010-01-21 Lg Chem. Ltd. Non-aqueous lithium secondary battery containing hydrophobic, inactive particle
CN105940530A (en) * 2014-03-24 2016-09-14 昭和电工株式会社 Slurry for positive electrode of lithium ion secondary cell, positive electrode obtained using said slurry, method for manufacturing said positive electrode, lithium ion secondary cell formed using said positive electrode, and method for manufacturing said cell
CN107785578A (en) * 2016-08-25 2018-03-09 宁德时代新能源科技股份有限公司 Positive electrode additive, preparation method thereof, positive plate and lithium ion secondary battery

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5846673A (en) * 1996-12-09 1998-12-08 Valence Technology, Inc. Additive to stabilize electrochemical cell
US20100015523A1 (en) * 2006-08-21 2010-01-21 Lg Chem. Ltd. Non-aqueous lithium secondary battery containing hydrophobic, inactive particle
CN105940530A (en) * 2014-03-24 2016-09-14 昭和电工株式会社 Slurry for positive electrode of lithium ion secondary cell, positive electrode obtained using said slurry, method for manufacturing said positive electrode, lithium ion secondary cell formed using said positive electrode, and method for manufacturing said cell
CN107785578A (en) * 2016-08-25 2018-03-09 宁德时代新能源科技股份有限公司 Positive electrode additive, preparation method thereof, positive plate and lithium ion secondary battery

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11817578B2 (en) * 2019-06-05 2023-11-14 Enevate Corporation Silicon-based energy storage devices with silyl amine compounds or derivatives of silyl amine containing electrolyte additives
CN112151755A (en) * 2020-09-08 2020-12-29 江苏塔菲尔新能源科技股份有限公司 Positive plate and battery
CN112054202A (en) * 2020-09-10 2020-12-08 辽宁九夷锂能股份有限公司 High-energy high-rate lithium battery positive electrode additive, preparation method thereof and positive plate containing positive electrode additive
CN112864346A (en) * 2021-01-12 2021-05-28 惠州亿纬锂能股份有限公司 Pole piece, preparation method thereof and battery
WO2023133798A1 (en) * 2022-01-14 2023-07-20 宁德时代新能源科技股份有限公司 Positive electrode composite material for lithium-ion secondary battery, positive electrode, and battery
CN115498246A (en) * 2022-09-22 2022-12-20 江苏正力新能电池技术有限公司 Lithium ion battery, battery module and battery pack
CN115579507A (en) * 2022-10-21 2023-01-06 江苏正力新能电池技术有限公司 Secondary battery and preparation method thereof, battery pack and power utilization device

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