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Negative pole piece and lithium ion battery

A technology of negative pole piece and conductive agent, which is applied in the field of negative pole piece and lithium-ion battery, can solve the problems of large volume expansion, achieve the effects of inhibiting volume expansion, increasing battery capacity, and preventing shedding

Pending Publication Date: 2022-02-22
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The present invention aims to solve the problem of large volume expansion of the negative electrode sheet with high capacity in the prior art during the battery cycle, and provides a negative electrode sheet and a lithium-ion battery. The negative electrode sheet not only has a higher capacity , and the volume change in the battery cycle is small, and the battery cycle performance is better

Method used

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  • Negative pole piece and lithium ion battery
  • Negative pole piece and lithium ion battery
  • Negative pole piece and lithium ion battery

Examples

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Embodiment 1

[0035] This embodiment is used to illustrate a negative electrode sheet and its preparation method disclosed in the present invention.

[0036] A mixture of silicon oxide as the first active material and graphite material as the second active material with a mass fraction of 80:20 is used as an active material material, and the active material material, the conductive material SP, and the binder material PAA are formulated according to The first negative electrode slurry L1 was prepared in parts by mass of 85:5:10. A mixture of silicon oxide as the first active material and natural graphite material as the second active material with a mass fraction of 50:50 is used as another active material, and the other active material is bonded to the conductive material SP, The agent material SBR and the thickener CMC were mixed according to the mass ratio of 95:5:2:3 to prepare the second negative electrode slurry L2. The first negative electrode slurry L1 is first coated on the curren...

Embodiment 2

[0038] This embodiment is used to illustrate another negative electrode sheet disclosed in the present invention and its preparation method.

[0039] The commercial 1200 silicon carbon as the first active material and the graphite mixture as the second active material with a weight ratio of 70:30 are used as an active material, and the active material and the conductive material SP and the binder material PAA are used according to 80 : 6.5: 13.5 mass ratio to make the first negative electrode slurry L1. The commercial 1200 silicon carbon as the first active material and the graphite mixture as the second active material with a weight ratio of 80:20 are used as another active material material, and the active material material is combined with the conductive material SP, the binder material SBR, The thickener CMC is used to make the second negative electrode slurry L2 according to the mass ratio of 95:5:2:3, and the first negative electrode slurry L1 is first coated on the copp...

Embodiment 3

[0041] This embodiment is used to illustrate another negative electrode sheet disclosed in the present invention and its preparation method.

[0042] The first active material commercial tin and the second active material graphite mixture with a weight ratio of 80:20 are used as an active material material, and the active material material, the conductive material SP, and the binder material PAA are used according to the mass ratio of 85:5:10 Compared with making the first negative electrode slurry L1, the artificial graphite material, the conductive material SP, the binder material SBR, and the thickener CMC are made into the second negative electrode slurry L2 according to the mass ratio of 95:5:2:3, and the first The negative electrode slurry L1 is first coated on the copper foil to obtain the first active material layer, after drying and pressing, the second negative electrode slurry L2 is coated on the first layer of active material layer, after drying and pressing, and th...

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Abstract

The invention provides a negative pole piece which comprises a current collector and an active layer. The active layer comprises a first active material, a second active material, a binder and a conductive agent. The gram volume of the first active material is higher than that of the second active material. The volume expansion rate of the first active material is higher than that of the second active material. The content of the binder is gradually reduced along the direction far away from the current collector. In the direction far away from the current collector, the content of the conductive agent and the content of the binder in secondary active layers are distributed in a step-by-step decreasing mode, and the multiple secondary active layers comprise a first active layer, a second active layer and a third active layer. Therefore, the active layers of the battery can be prevented from falling off, the conductivity of the negative pole piece is improved, so that the cycle performance and the capacity of the battery are improved, the capacity exertion of the active material is facilitated, there is more binder in the active layers in contact with the current collector, larger volume expansion of the first active material can be inhibited, the active layers are prevented from falling off, and the cycle performance of the battery can be improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a negative pole piece and a lithium ion battery. Background technique [0002] Lithium-ion batteries are widely used in 3C digital products because of their high energy density, long cycle life, no memory effect, and adjustable shape and size. And with the country's advocacy of energy saving and emission reduction, more and more attention is paid to the new energy industry, and lithium-ion batteries are widely used in automobiles as a new energy source. [0003] When a lithium-ion battery is being charged, lithium ions come out of the positive electrode into the electrolyte, pass through the separator to the surface of the negative electrode, and then intercalate into the micropores of the negative electrode. In the prior art, graphite material is used as the negative electrode material of lithium ion battery, and the theoretical specific capacity of gr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/13H01M10/058H01M10/0525H01M10/42
CPCH01M4/366H01M4/13H01M10/058H01M10/0525H01M10/4235Y02E60/10Y02P70/50
Inventor 孙安涛王蒙李世彩魏彦宽刘平
Owner BYD CO LTD
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