Lithium ion secondary battery pole piece and lithium ion secondary battery

A secondary battery, lithium ion technology, used in secondary batteries, secondary battery repair/maintenance, battery electrodes, etc. Safety issues and other issues, to achieve the effect of improving battery kinetic performance and cycle performance, good electrolyte absorption ability, and improving ion conductivity

Active Publication Date: 2020-09-29
东莞市魔方新能源科技有限公司
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AI Technical Summary

Problems solved by technology

[0005] However, in the above-mentioned technology, because lithium ions need to pass through the porous layer to generate a battery path, the polymer and electrolyte in the porous layer composed of inorganic particles have poor wettability, resulting in poor ion conductivity of the porous layer. , and because the porous layer composed of inorganic particles is an insulating layer to improve safety, the interface impedance of the battery increases, which affects the kinetic performance and cycle performance of the battery
[0006] In addition, in the lithium-ion battery, the negative electrode active material has a high expansion rate during the charging and discharging process of the battery, which leads to serious deformation of the battery. During the charging and discharging process of the battery, the porous layer composed of inorganic particles will be formed due to the deformation of the battery. Cracks, resulting in insufficient effect of suppressing internal short circuits, reducing battery safety issues

Method used

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  • Lithium ion secondary battery pole piece and lithium ion secondary battery

Examples

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preparation example Construction

[0038] (1) Preparation of porous insulating coating: dissolve the first binder in the first solvent to form a polymer solution, add dopamine-coated inorganic particles and mix uniformly, and evenly coat the prepared mixture on the active material on the surface of the layer, and then dried to obtain a porous insulating coating. The first solvent that can be used is not particularly limited, as long as it can dissolve the first binder and uniformly disperse the inorganic particles and can be easily removed during coating and drying, the first solvent includes but not limited to tetrahydrofuran, methyl ethyl ketone, dimethyl formamide , Dimethylacetamide, Tetramethylurea, Tetramethylphosphate, Acetone, Dichloromethane, Chloroform, Dimethylamide, N-Methylpyrrolidone (NMP), Cyclohexane, Water and mixtures thereof. The concentration of the first binder is 1-99wt%, preferably 30-60wt%. In order to coat the mixture of the dopamine-coated inorganic particles and the binder on the sur...

Embodiment 1

[0041] (1) Preparation of positive electrode sheet: Lithium cobalt oxide, conductive carbon, and binder polyvinylidene fluoride are mixed uniformly in N-methylpyrrolidone (NMP) solvent at a mass ratio of 96:2.0:2.0 to make positive electrode slurry, Then it is coated on aluminum foil and dried at 110°C to obtain a positive electrode sheet, which is then cold pressed and ready for use.

[0042] Preparation of porous insulating coating: add 13wt% polyacrylate emulsion (40% content in aqueous solution) to deionized water and stir for 1h, then add 85wt% dopamine-coated Al 2 o 3 After the particles were stirred for 2 hours, they were ground in a ball mill for 1 hour, and 2 wt% sodium carboxymethylcellulose (CMC) was added to the ground slurry, and the mixture was stirred for 1 hour to prepare a slurry. Then use the gravure coating to uniformly cover the above-mentioned slurry on both surfaces of the above-mentioned cold-pressed positive electrode, the coating thickness on both sid...

Embodiment 2

[0048](1) Preparation of positive electrode sheet: Lithium cobalt oxide, conductive carbon, and binder polyvinylidene fluoride are mixed uniformly in N-methylpyrrolidone (NMP) solvent at a mass ratio of 96:2.0:2.0 to make positive electrode slurry, Then it is coated on aluminum foil and dried at 110°C, then cold-pressed, stripped, trimmed, and lug-welded to make a positive electrode sheet.

[0049] (2) Preparation of negative electrode sheet: mix graphite, conductive carbon, thickener sodium carboxymethyl cellulose, and binder styrene-butadiene rubber in deionized water at a mass ratio of 95:2.0:1.0:2.0 to make negative electrode slurry material, and then coated on copper foil and dried at 85°C and then cold pressed for later use.

[0050] Preparation of porous insulating coating: add 13wt% polyacrylate emulsion (40% content in aqueous solution) to deionized water and stir for 1h, then add 85wt% dopamine-coated Al 2 o 3 After the particles were stirred for 2 hours, they were...

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Abstract

The invention belongs to the technical field of lithium ion batteries and particularly relates to a lithium-ion secondary battery pole piece. The lithium-ion secondary battery pole piece comprises a current collector and an active substance layer coated on at least one surface of the current collector, wherein a surface of the active substance layer is coated with a porous insulating coating, theporous insulating coating comprises dopamine-coated inorganic particles and a first binder, a surface of the porous insulating coating is further coated with organic coating, and the organic coating is distributed in an island shape and / or a linear shape. The lithium-ion secondary battery pole piece solves a problem that the inorganic porous layer coated on the surface of the diaphragm affects theperformance of the battery, and further solves a safety problem caused by the expansion of the negative electrode in the cycle process.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a pole piece of a lithium ion secondary battery and a lithium ion secondary battery. Background technique [0002] Since the commercialization of lithium-ion secondary batteries in the 1990s, due to their high energy density, high working voltage, and light weight, they have been widely used in mobile phones, notebook computers, tablet computers, Bluetooth headsets, MP3 and digital cameras. Applications. [0003] Lithium-ion batteries are mainly composed of positive and negative pole pieces and a separator in the middle. The separator is used as the isolation of the positive and negative electrodes to prevent the short circuit from direct contact between the positive and negative electrodes. At present, the separator is mainly a porous medium composed of polyolefins such as polyethylene and polypropylene. The polyolefin separator has a melting point of ...

Claims

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Application Information

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IPC IPC(8): H01M4/62H01M2/34H01M2/16H01M4/13H01M10/0525H01M10/058H01M10/42B82Y30/00
CPCB82Y30/00H01M4/13H01M4/62H01M10/0525H01M10/058H01M10/4235Y02E60/10Y02P70/50
Inventor 汪圣龙蒋中林
Owner 东莞市魔方新能源科技有限公司
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