CN112751079A - Lithium ion battery - Google Patents

Lithium ion battery Download PDF

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Publication number
CN112751079A
CN112751079A CN201911054091.6A CN201911054091A CN112751079A CN 112751079 A CN112751079 A CN 112751079A CN 201911054091 A CN201911054091 A CN 201911054091A CN 112751079 A CN112751079 A CN 112751079A
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China
Prior art keywords
ion battery
lithium ion
lithium
electrolyte
active material
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CN201911054091.6A
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Inventor
汪小知
龙照
卢文成
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Suzhou Weimu Intelligent System Co ltd
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Suzhou Weimu Intelligent System Co ltd
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Priority to CN201911054091.6A priority Critical patent/CN112751079A/en
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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
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention relates to the technical field of batteries, in particular to a lithium ion battery. The lithium ion battery provided by the invention comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, wherein the electrolyte comprises lithium salt, an organic solvent and an additive, the additive comprises amyl triborate, and the dosage of the additive is 0.05-0.3% of the mass of the electrolyte. According to the invention, the specific amyl triborate additive is added into the electrolyte, and the dosage of the additive is controlled to be 0.05-0.3% of the mass of the electrolyte, so that the cycle performance and high-temperature shelf performance of the battery can be improved.

Description

Lithium ion battery
Technical Field
The invention relates to the technical field of batteries, in particular to a lithium ion battery.
Background
With the continuous development of electronic and energy technologies, people are facing CO2And the attention on the emission of automobile exhaust is continuously increased, and the electric automobile becomes the development trend in the future. As one of the core components of electric vehicles, research and application of lithium ion batteries are receiving attention.
The existing lithium ion battery generally adopts a mixed solution of cyclic carbonate and/or chain carbonate as an electrolyte solvent. During battery cycling and storage, the solvent undergoes an irreversible redox reaction with the active surface of the electrode material, resulting in a decrease in battery performance. Therefore, a film forming additive is generally added into the electrolyte to form a protective film on the surface of the electrode, so that the reaction of the solvent and the electrode is prevented, and the cycle performance is improved. Although there are many types of film forming additives, such as vinylene carbonate, it can form a protective film on the surface of an electrode. However, the stability of the existing film forming additive for forming a protective film on the surface of an electrode is insufficient, and when the film forming additive is subjected to high-temperature charge-discharge cycle and high-temperature shelf, components of a part of the protective film are decomposed, so that the protective effect is lost, a solvent reacts with the electrode and is consumed, and the performance of a battery is reduced.
Disclosure of Invention
The invention aims to solve the problem that the cycle performance and high-temperature shelf performance of a battery are influenced because a film-forming additive cannot form a stable protective film on the surface of an electrode in the prior art, and further provides a lithium ion battery.
In order to achieve the purpose, the invention adopts the following technical scheme:
a lithium ion battery comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, wherein the electrolyte comprises lithium salt, an organic solvent and an additive, the additive comprises amyl trinitroborate, and the dosage of the additive is 0.05-0.3% of the mass of the electrolyte.
Preferably, the additive further comprises p-toluenesulfonylmethylisocyanamide.
Preferably, the mass ratio of the amyl triborate to the p-methyl benzenesulfonyl methyl isonitrile is 1: 0.5-1.5.
Preferably, the mass ratio of the amyl triborate to the p-toluenesulfonylmethylisocyanate is 1: 1.1.
Preferably, the amount of the lithium salt is 0.5-1.0% of the mass of the electrolyte.
Preferably, the lithium salt is selected from LiPF6、LiBF4One or more of LiBOB and liddob;
the organic solvent is selected from one or more of methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, ethyl acetate and methyl acetate.
Preferably, the negative electrode plate comprises a negative electrode current collector, and a carbon-containing conductive coating and an active material layer which are sequentially stacked on the surface of the negative electrode current collector, wherein the carbon-containing conductive coating is made of graphene; and forming the carbon-containing conductive coating on the surface of the negative current collector by the graphene through a chemical vapor deposition method. In the present invention, the chemical vapor deposition method is a conventional preparation method in the art. The step of forming the carbon-containing conductive coating on the surface of the negative current collector by a chemical vapor deposition method comprises the following steps: putting the negative current collector into a reaction chamber for chemical vapor deposition, and introducing C when the temperature in the reaction chamber reaches 810 DEG C2H2Ar/C with a content of 8%2H2Mixing the gases, and preserving the heat for 0.5h to obtain the negative current collector with the surface containing the carbon-containing conductive coating after the heat preservation is finished.
Preferably, the active material layer includes a negative electrode active material, a binder, and a conductive agent,
the negative active material is selected from one or more of artificial graphite, natural graphite and silicon carbide;
the binder is one or more selected from polyvinylidene fluoride, styrene-acrylate copolymer, polyacrylonitrile, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone and polyvinyl ether;
the conductive agent is selected from one or more of conductive carbon black, lamellar graphite and carbon fiber.
Preferably, the negative electrode current collector is a copper foil or an aluminum foil.
Preferably, the positive electrode piece comprises a positive active material, and the positive active material is selected from one or more of lithium cobaltate, lithium manganate, lithium nickel cobalt manganate, lithium iron phosphate, lithium nickel cobalt aluminate, lithium nickel cobalt oxide, and lithium nickel oxide.
The invention has the beneficial effects that:
1) the lithium ion battery provided by the invention comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, wherein the electrolyte comprises lithium salt, an organic solvent and an additive, a specific amyl tri-n-borate additive is added into the electrolyte, the dosage of the additive is controlled to be 0.05-0.3% of the mass of the electrolyte, and the amyl tri-n-borate is beneficial to forming a layer of stable oxide film on the surface of an electrode material in the process of first charging and discharging of the battery, so that the contact between the electrolyte and an electrode active substance can be inhibited, and the cycle performance and the high-temperature shelf performance of the battery are obviously improved.
2) In the lithium ion battery provided by the invention, the additive further comprises p-methyl benzenesulfonyl methyl isonitrile. According to the invention, the p-methyl benzenesulfonyl methyl isonitrile is added, and the p-methyl benzenesulfonyl methyl isonitrile interacts with the isonitrile group through the specific space structure of the p-methyl benzenesulfonyl methyl and is matched with the amyl triborate, so that a stable oxide film is formed on the surface of an electrode material, and the cycle performance and the high-temperature shelf performance of the battery are improved. Furthermore, the mass ratio of the amyl triborate to the p-methyl benzenesulfonyl methyl isonitrile is 1:0.5-1.5, and the inventor finds that the effect of improving the cycle performance and the high-temperature shelf performance of the battery is more remarkable under the specific ratio through a great deal of research.
3) Further, the material in the carbon-containing conductive coating is graphene; and forming the carbon-containing conductive coating on the surface of the negative current collector by the graphene through a chemical vapor deposition method. Compared with the existing wet coating technology, the method has the advantages of simple operation, short preparation period and uniform prepared carbon-containing conductive coating.
Detailed Description
The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
Example 1
The embodiment provides a lithium ion battery, which comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, wherein the negative pole piece comprises a negative pole current collector, and a carbon-containing conductive coating and an active material layer which are sequentially stacked on the surface of the negative pole current collector, and the active material layer comprises a negative active material;
the electrolyte comprises lithium salt, an organic solvent and an additive, wherein the additive is amyl trinitroborate, and the dosage of the additive is 0.05 percent of the mass of the electrolyte; the lithium salt is LiPF6The organic solvent is dimethyl carbonate, and the amount of the lithium salt is 1.0 percent of the mass of the electrolyte;
the cathode active material is artificial graphite, the cathode current collector is copper foil, a graphene layer (namely a carbon-containing conductive coating) is formed on the surface of the copper foil through a chemical vapor deposition method, the thickness of the graphene layer is 20nm, the cathode conductive agent is conductive carbon black, and the cathode binder is sodium carboxymethyl cellulose;
LiNi is selected as the positive electrode active material0.5Co0.2Mn0.3O2The positive conductive agent is conductive carbon black, and the positive current collector is aluminum foil; the diaphragm is made of polyethylene with ceramic coated on the surface, and the average porosity is 47 percent; the battery adopts an end face welding structure and is packaged by an aluminum plastic film.
The preparation method of the lithium ion battery comprises the following steps:
(1) preparing a positive pole piece: polyvinylidene fluoride and NMP (N-methyl pyrrolidone) are added into a stirrer according to the mass ratio of 4:96, the stirring speed is 40rpm, and the stirring is carried out for 1.5 h; after stirring, adding conductive carbon black (conductive agent) into the mixture, and stirring the mixture for 2 hours at the stirring speed of 40 rpm; adding LiNi0.5Co0.2Mn0.3O2Stirring for 2 hours at the stirring speed of 30 rpm; after stirring, the obtained slurry is filtered by a 150-mesh screen, coated on an aluminum foil, and the density of the single surface is controlledThe degree is 7.5mg/cm2And rolled to 82 μm; wherein the mass ratio of the positive electrode active substance to the conductive agent to the polyvinylidene fluoride is 96.5:2: 1.5;
(2) preparing a negative pole piece: adding CMC (sodium carboxymethylcellulose) and pure water into a stirrer according to the mass ratio of 1:80, stirring at the speed of 30rpm, and stirring for 2 hours; adding conductive carbon black (conductive agent) with the stirring speed of 35rpm, and stirring for 2 h; adding artificial graphite serving as a negative active material, stirring at the speed of 30rpm for 3 hours; after stirring, the obtained slurry is screened by a 120-mesh screen, coated on a copper foil with a graphene layer coated on the surface, and the single-side surface density is controlled to be 4.5mg/cm2And rolled to 85 μm; wherein, the negative electrode active material comprises, by mass: conductive carbon black: CMC 96:2.0: 2.0.
(3) Preparing an electrolyte: and mixing the lithium salt, the organic solvent and the additive at normal temperature to obtain the electrolyte.
(4) Assembling, injecting liquid, forming, baking a clamp and grading: cutting and baking the positive and negative pole pieces, winding the positive and negative pole pieces and a polyethylene ceramic diaphragm into a naked battery cell, and then performing procedures of tab welding, aluminum plastic film packaging, baking, electrolyte injection, simple packaging, high-temperature shelving, formation, clamp baking, secondary sealing and capacity grading to manufacture the soft package battery cell.
Example 2
The embodiment provides a lithium ion battery, which comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, wherein the negative pole piece comprises a negative pole current collector, and a carbon-containing conductive coating and an active material layer which are sequentially stacked on the surface of the negative pole current collector, and the active material layer comprises a negative active material;
the electrolyte comprises lithium salt, an organic solvent and an additive, wherein the additive is amyl trinitroborate, and the dosage of the additive is 0.3 percent of the mass of the electrolyte; the lithium salt is LiPF6The organic solvent is diethyl carbonate, and the amount of the lithium salt is 0.5 percent of the mass of the electrolyte;
the cathode active material is natural graphite, the cathode current collector is copper foil, a graphene layer (namely a carbon-containing conductive coating) is formed on the surface of the copper foil through a chemical vapor deposition method, the thickness of the graphene layer is 20nm, the cathode conductive agent is flake carbon black, and the cathode binder is sodium carboxymethyl cellulose;
LiNi is selected as the positive electrode active material0.5Co0.2Mn0.3O2The positive conductive agent is conductive carbon black, and the positive current collector is aluminum foil; the diaphragm is made of polyethylene with ceramic coated on the surface, and the average porosity is 47 percent; the battery adopts an end face welding structure and is packaged by an aluminum plastic film.
The preparation method of the lithium ion battery comprises the following steps:
(1) preparing a positive pole piece: polyvinylidene fluoride and NMP (N-methyl pyrrolidone) are added into a stirrer according to the mass ratio of 4:96, the stirring speed is 40rpm, and the stirring is carried out for 1.5 h; after stirring, adding conductive carbon black (conductive agent) into the mixture, and stirring the mixture for 2 hours at the stirring speed of 40 rpm; adding LiNi0.5Co0.2Mn0.3O2Stirring for 2 hours at the stirring speed of 30 rpm; after the stirring, the obtained slurry is filtered by a 150-mesh screen, coated on an aluminum foil, and the single-side surface density is controlled to be 7.5mg/cm2And rolled to 82 μm; wherein the mass ratio of the positive electrode active substance to the conductive agent to the polyvinylidene fluoride is 96.5:2: 1.5;
(2) preparing a negative pole piece: adding CMC (sodium carboxymethylcellulose) and pure water into a stirrer according to the mass ratio of 1:80, stirring at the speed of 35rpm, and stirring for 2 hours; adding flake carbon black (conductive agent) with the stirring speed of 35rpm, and stirring for 2 h; adding natural graphite as a negative active material, stirring at 40rpm for 3 h; after stirring, the obtained slurry is screened by a 120-mesh screen, coated on a copper foil with a graphene layer coated on the surface, and the single-side surface density is controlled to be 4.5mg/cm2And rolled to 85 μm; wherein, the negative electrode active material comprises, by mass: flake carbon black: CMC 96:2.0: 2.0.
(3) Preparing an electrolyte: and mixing the lithium salt, the organic solvent and the additive at normal temperature to obtain the electrolyte.
(4) Assembling, injecting liquid, forming, baking a clamp and grading: cutting and baking the positive and negative pole pieces, winding the positive and negative pole pieces and a polyethylene ceramic diaphragm into a naked battery cell, and then performing procedures of tab welding, aluminum plastic film packaging, baking, electrolyte injection, simple packaging, high-temperature shelving, formation, clamp baking, secondary sealing and capacity grading to manufacture the soft package battery cell.
Example 3
The embodiment provides a lithium ion battery, which comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, wherein the negative pole piece comprises a negative pole current collector, and a carbon-containing conductive coating and an active material layer which are sequentially stacked on the surface of the negative pole current collector, and the active material layer comprises a negative active material;
the electrolyte comprises lithium salt, an organic solvent and an additive, wherein the additive is amyl tri-n-borate and p-methyl benzenesulfonyl methyl isonitrile, the mass ratio of the amyl tri-n-borate to the p-methyl benzenesulfonyl methyl isonitrile is 1:0.5, and the using amount of the additive is 0.05% of the mass of the electrolyte; the lithium salt is LiPF6The organic solvent is dimethyl carbonate, and the amount of the lithium salt is 1.0 percent of the mass of the electrolyte;
the cathode active material is artificial graphite, the cathode current collector is copper foil, a graphene layer (namely a carbon-containing conductive coating) is formed on the surface of the copper foil through a chemical vapor deposition method, the thickness of the graphene layer is 20nm, the cathode conductive agent is conductive carbon black, and the cathode binder is sodium carboxymethyl cellulose;
LiNi is selected as the positive electrode active material0.5Co0.2Mn0.3O2The positive conductive agent is conductive carbon black, and the positive current collector is aluminum foil; the diaphragm is made of polyethylene with ceramic coated on the surface, and the average porosity is 47 percent; the battery adopts an end face welding structure and is packaged by an aluminum plastic film.
The preparation method of the lithium ion battery comprises the following steps:
(1) preparing a positive pole piece: polyvinylidene fluoride and NMP (N-methyl pyrrolidone) are added into a stirrer according to the mass ratio of 4:96, the stirring speed is 40rpm, and the stirring is carried out for 1.5 h; after stirring, adding conductive carbon black (conductive agent) into the mixture, and stirring the mixture for 2 hours at the stirring speed of 40 rpm; adding LiNi0.5Co0.2Mn0.3O2Stirring for 2 hours at the stirring speed of 30 rpm; after the stirring is finished, the obtained slurry is filtered by 1A 50-mesh screen coated on the aluminum foil, and the single-side surface density is controlled to be 7.5mg/cm2And rolled to 82 μm; wherein the mass ratio of the positive electrode active substance to the conductive agent to the polyvinylidene fluoride is 96.5:2: 1.5;
(2) preparing a negative pole piece: adding CMC (sodium carboxymethylcellulose) and pure water into a stirrer according to the mass ratio of 1:80, stirring at the speed of 30rpm, and stirring for 2 hours; adding conductive carbon black (conductive agent) with the stirring speed of 35rpm, and stirring for 2 h; adding artificial graphite serving as a negative active material, stirring at the speed of 30rpm for 3 hours; after stirring, the obtained slurry is screened by a 120-mesh screen, coated on a copper foil with a graphene layer coated on the surface, and the single-side surface density is controlled to be 4.5mg/cm2And rolled to 85 μm; wherein, the negative electrode active material comprises, by mass: conductive carbon black: CMC 96:2.0: 2.0.
(3) Preparing an electrolyte: and mixing the lithium salt, the organic solvent and the additive at normal temperature to obtain the electrolyte.
(4) Assembling, injecting liquid, forming, baking a clamp and grading: cutting and baking the positive and negative pole pieces, winding the positive and negative pole pieces and a polyethylene ceramic diaphragm into a naked battery cell, and then performing procedures of tab welding, aluminum plastic film packaging, baking, electrolyte injection, simple packaging, high-temperature shelving, formation, clamp baking, secondary sealing and capacity grading to manufacture the soft package battery cell.
Example 4
The embodiment provides a lithium ion battery, which comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, wherein the negative pole piece comprises a negative pole current collector, and a carbon-containing conductive coating and an active material layer which are sequentially stacked on the surface of the negative pole current collector, and the active material layer comprises a negative active material;
the electrolyte comprises lithium salt, an organic solvent and an additive, wherein the additive is amyl tri-n-borate and p-methyl benzenesulfonyl methyl isonitrile, the mass ratio of the amyl tri-n-borate to the p-methyl benzenesulfonyl methyl isonitrile is 1:1.5, and the using amount of the additive is 0.05% of the mass of the electrolyte; the lithium salt is LiPF6The organic solvent is dimethyl carbonate, and the amount of the lithium salt is 1.0 percent of the mass of the electrolyte;
the cathode active material is artificial graphite, the cathode current collector is copper foil, a graphene layer (namely a carbon-containing conductive coating) is formed on the surface of the copper foil through a chemical vapor deposition method, the thickness of the graphene layer is 20nm, the cathode conductive agent is conductive carbon black, and the cathode binder is sodium carboxymethyl cellulose;
LiNi is selected as the positive electrode active material0.5Co0.2Mn0.3O2The positive conductive agent is conductive carbon black, and the positive current collector is aluminum foil; the diaphragm is made of polyethylene with ceramic coated on the surface, and the average porosity is 47 percent; the battery adopts an end face welding structure and is packaged by an aluminum plastic film.
The preparation method of the lithium ion battery comprises the following steps:
(1) preparing a positive pole piece: polyvinylidene fluoride and NMP (N-methyl pyrrolidone) are added into a stirrer according to the mass ratio of 4:96, the stirring speed is 40rpm, and the stirring is carried out for 1.5 h; after stirring, adding conductive carbon black (conductive agent) into the mixture, and stirring the mixture for 2 hours at the stirring speed of 40 rpm; adding LiNi0.5Co0.2Mn0.3O2Stirring for 2 hours at the stirring speed of 30 rpm; after the stirring, the obtained slurry is filtered by a 150-mesh screen, coated on an aluminum foil, and the single-side surface density is controlled to be 7.5mg/cm2And rolled to 82 μm; wherein the mass ratio of the positive electrode active substance to the conductive agent to the polyvinylidene fluoride is 96.5:2: 1.5;
(2) preparing a negative pole piece: adding CMC (sodium carboxymethylcellulose) and pure water into a stirrer according to the mass ratio of 1:80, stirring at the speed of 30rpm, and stirring for 2 hours; adding conductive carbon black (conductive agent) with the stirring speed of 35rpm, and stirring for 2 h; adding artificial graphite serving as a negative active material, stirring at the speed of 30rpm for 3 hours; after stirring, the obtained slurry is screened by a 120-mesh screen, coated on a copper foil with a graphene layer coated on the surface, and the single-side surface density is controlled to be 4.5mg/cm2And rolled to 85 μm; wherein, the negative electrode active material comprises, by mass: conductive carbon black: CMC 96:2.0: 2.0.
(3) Preparing an electrolyte: and mixing the lithium salt, the organic solvent and the additive at normal temperature to obtain the electrolyte.
(4) Assembling, injecting liquid, forming, baking a clamp and grading: cutting and baking the positive and negative pole pieces, winding the positive and negative pole pieces and a polyethylene ceramic diaphragm into a naked battery cell, and then performing procedures of tab welding, aluminum plastic film packaging, baking, electrolyte injection, simple packaging, high-temperature shelving, formation, clamp baking, secondary sealing and capacity grading to manufacture the soft package battery cell.
Example 5
The embodiment provides a lithium ion battery, which comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, wherein the negative pole piece comprises a negative pole current collector, and a carbon-containing conductive coating and an active material layer which are sequentially stacked on the surface of the negative pole current collector, and the active material layer comprises a negative active material;
the electrolyte comprises lithium salt, an organic solvent and an additive, wherein the additive is amyl tri-n-borate and p-methyl benzenesulfonyl methyl isonitrile, the mass ratio of the amyl tri-n-borate to the p-methyl benzenesulfonyl methyl isonitrile is 1:1.1, and the using amount of the additive is 0.05% of the mass of the electrolyte; the lithium salt is LiPF6The organic solvent is dimethyl carbonate, and the amount of the lithium salt is 1.0 percent of the mass of the electrolyte;
the cathode active material is artificial graphite, the cathode current collector is copper foil, a graphene layer (namely a carbon-containing conductive coating) is formed on the surface of the copper foil through a chemical vapor deposition method, the thickness of the graphene layer is 20nm, the cathode conductive agent is conductive carbon black, and the cathode binder is sodium carboxymethyl cellulose;
LiNi is selected as the positive electrode active material0.5Co0.2Mn0.3O2The positive conductive agent is conductive carbon black, and the positive current collector is aluminum foil; the diaphragm is made of polyethylene with ceramic coated on the surface, and the average porosity is 47 percent; the battery adopts an end face welding structure and is packaged by an aluminum plastic film.
The preparation method of the lithium ion battery comprises the following steps:
(1) preparing a positive pole piece: polyvinylidene fluoride and NMP (N-methyl pyrrolidone) are added into a stirrer according to the mass ratio of 4:96, the stirring speed is 40rpm, and the stirring is carried out for 1.5 h; after the stirring, the conductive carbon black (conductive agent) is added thereto, and the mixture is stirredStirring at 40rpm for 2 h; adding LiNi0.5Co0.2Mn0.3O2Stirring for 2 hours at the stirring speed of 30 rpm; after the stirring, the obtained slurry is filtered by a 150-mesh screen, coated on an aluminum foil, and the single-side surface density is controlled to be 7.5mg/cm2And rolled to 82 μm; wherein the mass ratio of the positive electrode active substance to the conductive agent to the polyvinylidene fluoride is 96.5:2: 1.5;
(2) preparing a negative pole piece: adding CMC (sodium carboxymethylcellulose) and pure water into a stirrer according to the mass ratio of 1:80, stirring at the speed of 30rpm, and stirring for 2 hours; adding conductive carbon black (conductive agent) with the stirring speed of 35rpm, and stirring for 2 h; adding artificial graphite serving as a negative active material, stirring at the speed of 30rpm for 3 hours; after stirring, the obtained slurry is screened by a 120-mesh screen, coated on a copper foil with a graphene layer coated on the surface, and the single-side surface density is controlled to be 4.5mg/cm2And rolled to 85 μm; wherein, the negative electrode active material comprises, by mass: conductive carbon black: CMC 96:2.0: 2.0.
(3) Preparing an electrolyte: and mixing the lithium salt, the organic solvent and the additive at normal temperature to obtain the electrolyte.
(4) Assembling, injecting liquid, forming, baking a clamp and grading: cutting and baking the positive and negative pole pieces, winding the positive and negative pole pieces and a polyethylene ceramic diaphragm into a naked battery cell, and then performing procedures of tab welding, aluminum plastic film packaging, baking, electrolyte injection, simple packaging, high-temperature shelving, formation, clamp baking, secondary sealing and capacity grading to manufacture the soft package battery cell.
Comparative example 1
This comparative example provides a lithium ion battery which differs from example 5 in that amyl tri-n-borate and p-toluenesulfonylmethylisocyanate are not added to the electrolyte.
Comparative example 2
This comparative example provides a lithium ion battery which differs from example 5 in that the additives pentyl tri-n-borate and p-toluenesulfonylmethyl isonitrile in the electrolyte are replaced by n-butyl isonitrile.
And (3) performance testing:
the lithium ion batteries obtained in the above examples and comparative examples were subjected to a performance test in which,
cycle performance: charging to 4.45V at 25 deg.C with 0.5C constant current, charging to current less than 0.05C at 4.45V constant voltage, standing for 5 min, and discharging to 3.0V with 0.5C current constant current, wherein the discharge capacity is the first discharge capacity. The capacity retention rate was 100% of the capacity at the 400 th week/first discharge capacity when the charge and discharge system was cycled for 400 weeks.
High-temperature shelf life: charging to 4.45V at 25 deg.C with 0.5C constant current, charging to current less than 0.02C at 4.45V constant voltage, standing for 5 min, and discharging to 3.0V with 0.5C current constant current, wherein the discharge capacity is the first discharge capacity. Charging to 4.45V with constant current of 0.5C, charging to current of less than 0.02C with constant voltage of 4.45V, and measuring the thickness of the battery with vernier caliper after stopping charging to obtain the initial thickness. The fully charged cell was placed in a forced air oven at 85 ℃ for 6 hours, and then taken out, and the cell thickness was measured with a vernier caliper, with the rate of change in thickness being (thickness after 6 hours-initial thickness)/initial thickness 100%. And discharging the shelved battery to 3.0V at a constant current of 0.5C to obtain the capacity kept after shelving. Capacity retention rate is 100% capacity retained after resting/first discharge capacity.
The results are shown in Table 1.
TABLE 1 lithium ion Battery Performance test
Figure BDA0002256079000000091
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims (10)

1. A lithium ion battery comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, and is characterized in that the electrolyte comprises lithium salt, an organic solvent and an additive, the additive comprises amyl triborate, and the dosage of the additive is 0.05-0.3% of the mass of the electrolyte.
2. The lithium ion battery of claim 1, wherein the additive further comprises p-toluenesulfonylmethylisocyanamide.
3. The lithium ion battery according to claim 1 or 2, wherein the mass ratio of the amyl tri-n-borate to the p-toluenesulfonylmethyl isonitrile is 1: 0.5-1.5.
4. The lithium ion battery according to any one of claims 1 to 3, wherein the mass ratio of the pentyl trinitroborate to the p-toluenesulfonylmethylisocyanitrile is 1: 1.1.
5. The lithium ion battery according to any one of claims 1 to 4, wherein the amount of the lithium salt is 0.5 to 1.0% by mass of the electrolyte.
6. The lithium ion battery of any one of claims 1-5, wherein the lithium salt is selected from LiPF6、LiBF4One or more of LiBOB and liddob;
the organic solvent is selected from one or more of methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, ethyl acetate and methyl acetate.
7. The lithium ion battery according to any one of claims 1 to 6, wherein the negative electrode plate comprises a negative electrode current collector, and a carbon-containing conductive coating and an active material layer which are sequentially stacked on the surface of the negative electrode current collector, wherein the carbon-containing conductive coating is made of graphene; and forming the carbon-containing conductive coating on the surface of the negative current collector by the graphene through a chemical vapor deposition method.
8. The lithium ion battery according to claim 7, wherein the active material layer comprises a negative electrode active material, a binder, and a conductive agent,
the negative active material is selected from one or more of artificial graphite, natural graphite and silicon carbide;
the binder is one or more selected from polyvinylidene fluoride, styrene-acrylate copolymer, polyacrylonitrile, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone and polyvinyl ether;
the conductive agent is selected from one or more of conductive carbon black, lamellar graphite and carbon fiber.
9. The lithium ion battery of any one of claims 1-8, wherein the negative current collector is a copper foil or an aluminum foil.
10. The lithium ion battery according to any one of claims 1 to 9, wherein the positive electrode sheet comprises a positive active material, and the positive active material is selected from one or more of lithium cobaltate, lithium manganate, lithium nickel cobalt manganate, lithium iron phosphate, lithium nickel cobalt aluminate, lithium nickel cobaltate, and lithium nickelate.
CN201911054091.6A 2019-10-31 2019-10-31 Lithium ion battery Pending CN112751079A (en)

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