Composite negative plate and lithium ion battery comprising same

A technology of negative electrode and negative electrode, which is applied in the field of composite negative electrode and lithium ion battery containing the negative electrode, can solve the problems of difficult to obtain rate and cycle performance, poor rate or cycle performance, and poor stability, so as to improve the rate and Effects of cycle performance, improvement of lithium ion conductivity, and improvement of mutual compatibility

Pending Publication Date: 2021-07-20
WANXIANG 123 CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, materials with high actual expansion coefficient have high energy density and poor rate or cycle performance
According to the research results of Koffi P.C.Yao et al., polarization will lead to a gradient distribution of lithium ion concentration in the pole piece, and the battery rate performance is more limited by the surface layer of the pole piece.
The alloy negative electrode with a high expansion coefficient is exposed on the outer layer of the negative electrode sheet, and it is difficult to obtain a rate and cycle performance significantly better than that of the outermost layer material, that is, it is difficult to obtain excellent rate and cycle performance. Swelling causes crushing and falling off, so there is also a problem of poor stability
Chinese Patent Announcement No. CN108039453A, dated May 15, 2018, titled A Method for Using Coating to Improve the Cycling Performance of Lithium Battery Negative Electrodes. It discloses the use of organic silicon fluororesin and lithium-based compound mixed coating on the surface of the negative electrode sheet. layer, reduce the corrosion of the electrolyte to the negative electrode material, inhibit the volume deformation of the negative electrode material during the cycle, and improve the cycle performance of the lithium battery, but the composite coating does not contribute to the capacity, nor can it improve the rate performance of the battery

Method used

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  • Composite negative plate and lithium ion battery comprising same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] (1) Preparation of positive electrode sheet: 96g of lithium iron phosphate, 0.3g of graphene, 1.5g of carbon black, 0.2g of carbon nanotubes, 2g of polyvinylidene fluoride, 65g of N-N-dimethylpyrrolidone, fully stirred and dispersed to form a slurry, Evenly coated on the calendered aluminum foil of the positive electrode current collector, rolled after drying to make the positive electrode sheet.

[0025] (2) Prepare the inner layer of the negative electrode sheet: 94.5g of artificial graphite, 1.5g of carbon black, 1.5g of sodium carboxymethyl cellulose, 2.5g of styrene-butadiene rubber, 120g of deionized water, stir to form a slurry, and evenly coat the negative electrode The current collector is placed on the electrolytic copper foil, and rolled after drying.

[0026] Outer layer: 93g of soft carbon, 1g of Li2S-P2S5, 2.5g of carbon black, 2g of sodium carboxymethyl cellulose, 2.5g of styrene-butadiene rubber, 180g of deionized water, stirred to form a slurry, and eve...

Embodiment 2

[0029] (1) Preparation of positive electrode sheet: 96g of lithium iron phosphate, 0.3g of graphene, 1.5g of carbon black, 0.2g of carbon nanotubes, 2g of polyvinylidene fluoride, 65g of N-N-dimethylpyrrolidone, fully stirred and dispersed to form a slurry, Evenly coated on the calendered aluminum foil of the positive electrode current collector, rolled after drying to make the positive electrode sheet.

[0030] (2) Preparation of negative pole piece

[0031] Inner layer: 88g of artificial graphite, 4.5g of carbon nanotubes, 3g of sodium carboxymethyl cellulose, 4.5g of polyvinylidene fluoride, 120g of deionized water, stirred to form a slurry, and evenly coated on the negative electrode current collector electrolytic copper foil, Roll pressing after drying.

[0032] Outer layer: Lithium titanate 86g, Li2S-SiS2 0.5g, graphene 4.5g, sodium carboxymethyl cellulose 4.5g, polyurethane 4.5g, deionized water 180g, stir to form a slurry, evenly coated on the inner layer of the negat...

Embodiment 3

[0035] (1) Preparation of positive electrode sheet: 96g of lithium iron phosphate, 0.3g of graphene, 1.5g of carbon black, 0.2g of carbon nanotubes, 2g of polyvinylidene fluoride, 65g of N-N-dimethylpyrrolidone, fully stirred and dispersed to form a slurry, Evenly coated on the calendered aluminum foil of the positive electrode current collector, rolled after drying to make the positive electrode sheet.

[0036] (2) Prepare the inner layer of the negative pole piece: 98.6g of artificial graphite, 0.4g of carbon fiber, 0.5g of polyvinylpyrrolidone, 0.5g of polyacrylic acid, 120g of deionized water, stir to form a slurry, and evenly coat the electrolytic copper foil on the negative current collector On, roll after drying.

[0037]Outer layer: lead telluride 98.6g, Li2S-B2S3 2g, conductive graphite 0.4g, polyvinylpyrrolidone 0.5g, polysodium alginate 0.5g, deionized water 180g, stir to form a slurry, evenly coated on the inner layer of the negative electrode On the sheet, the th...

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Abstract

The invention relates to the technical field of lithium ion batteries, and discloses a composite negative plate and a lithium ion battery comprising the same. According to the composite negative plate disclosed by the invention, the outer layer is made of the negative electrode material with good multiplying power, so that the multiplying power performance of the lithium ion battery can be ensured, the inner layer is made of the negative electrode material with high energy density, so that the energy density of the lithium ion battery can be ensured, and on the other hand, due to the buffering and protecting effects of the outer layer, the cycle performance can also be improved; according to the lithium ion battery assembled by using the composite negative pole piece, the high energy density can be ensured, and meanwhile, the multiplying power and the cycle performance can be obviously improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a composite negative electrode sheet and a lithium ion battery comprising the negative electrode sheet. Background technique [0002] With the application in the field of high-performance power batteries, the requirements for lithium-ion batteries are getting higher and higher, especially at the same time requiring excellent energy density, rate and cycle performance. However, although there are many types of lithium battery anode materials researched and developed, each with its own characteristics, none of them can achieve excellent performance in all aspects at the same time, especially it is difficult to balance energy density and rate performance at the same time. For example, materials such as silicon-based and tin-based materials have high capacity, but poor efficiency, rate, and cycle performance; lithium titanate has good rate and cycle performance, but low...

Claims

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Application Information

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IPC IPC(8): H01M4/131H01M4/133H01M4/136H01M4/36H01M4/485H01M4/58H01M4/587H01M4/62H01M10/0525
CPCH01M4/366H01M4/628H01M4/624H01M4/587H01M4/133H01M4/131H01M4/485H01M4/581H01M4/136H01M10/0525H01M2004/021H01M2004/027Y02E60/10
Inventor 颜立清王军华
Owner WANXIANG 123 CO LTD
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