Negative plate and lithium ion battery comprising same

A technology of negative electrode sheet and negative electrode, applied in the direction of negative electrode, battery electrode, secondary battery, etc., can solve the problem that the bonding force between the negative electrode active material layer and the current collector cannot be improved, the energy density and service life of the battery can be reduced, and the electrode material can be pulverized. and other problems, to achieve the effect of light weight, buffer volume expansion, and increased liquid retention

Pending Publication Date: 2020-11-10
ZHUHAI COSMX BATTERY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, during the charging and discharging process of the battery, the silicon-based material will experience a huge volume expansion (>280%), which will cause the electrode material to pulverize and fall off the surface of the current collector during the cycle, resulting in a huge capacity loss, which is also greatly Reduced battery energy density and service life
[0004] The current common practice is to improve the negative electrode sheet to alleviate the capacity attenuation caused by volume expansion, but most methods can only alleviate the volume expansion of silicon carbon materials, and cannot improve the bonding force between the negative electrode active material layer and the current collector.

Method used

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  • Negative plate and lithium ion battery comprising same
  • Negative plate and lithium ion battery comprising same
  • Negative plate and lithium ion battery comprising same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0084] (1) Preparation of positive electrode sheet:

[0085] The cathode active material LiCoO 2 , the binder PVDF, and the conductive agent Super P are dissolved in N-methylpyrrolidone (NMP) according to the mass ratio of 97:1.5:1.5 and stirred evenly to make a slurry, which is evenly coated on the aluminum foil of the positive electrode current collector, and dried. After rolling, it is made into the positive electrode sheet of the lithium-ion battery;

[0086] (2) Preparation of binder in porous copper foil:

[0087] 0.95 g of PVDF and 0.05 g of PVP were mixed and dissolved in 1.2 g of NMP, and dispersed at a speed of 800 rpm for 20 minutes to obtain a binder glue solution with a solid content of 5%-10%.

[0088] (3) Preparation of active material layer slurry:

[0089] SiO 2 / C composite material (SiO 2 Accounting for 20% of the total mass of the composite, SiO 2 The particle size is 1-7μm), the conductive agent conductive carbon black Super P, the binder water-emuls...

Embodiment 2

[0099] The difference between this embodiment and embodiment 1 is:

[0100] Preparation of binder in porous copper foil: mix 0.9g of PVDF and 0.1g of PVP and dissolve in 1.2g of NMP, disperse at 800rpm for 20min, and obtain a binder with a solid content of 5%-10% liquid.

[0101] The silicon-based material adopts Si / C composite material (Si accounts for 10% of the total mass of the composite material), and the carbon-based material adopts graphene, D 50 ≤1μm; the midline of the surface density of the bottom coating is 0.00856g / cm 2 , the median line density of the top layer coating is 0.00214g / cm 2 After drying, the thickness of the carbon-based material layer on one side of the porous copper foil is 20±3μm, and the thickness of the active material layer is 80±3μm; the rolling compaction density is 1.70g / cm 3 .

Embodiment 3

[0103] The difference between this embodiment and embodiment 1 is:

[0104] Preparation of binder in porous copper foil: Dissolve 1g of PAA-Na in 1.2g of NMP, disperse at 1000rpm for 20min, and obtain a binder solution with a solid content of 5%-10%.

[0105] Silicon-based materials using SiO 2 / C composite material (SiO 2 Accounting for 20% of the total mass of the composite material), the carbon-based material is a mixed material of artificial graphite and carbon nanotube CNT, the mass ratio of artificial graphite and carbon nanotube CNT is 7:3, and the particle size of the mixed material is D 50 ≤10μm; the midline of the surface density of the bottom coating is 0.00726g / cm 2 , the median density of the top coating area is 0.00484g / cm 2 .

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Abstract

The invention provides a negative plate and a lithium ion battery comprising the same. The invention discloses a lithium ion battery negative plate. A porous copper foil filled with a binder is adopted as a negative current collector, the liquid retention amount of the negative plate is improved due to the existence of pores in the porous copper foil, the porous copper foil is lighter than commonlight foil, the overall mass specific energy of a battery cell can be improved, and the flexibility of the negative plate is also improved; the binder filled in the pores greatly improves the bindingpower between the active material layer and the negative electrode current collector, avoids stripping of the active material layer from the negative electrode current collector due to large volume expansion of the silicon-based material, and reduces the contact resistance between the silicon-based material and the negative electrode current collector; and the silicon-based material is used, so the overall capacity of the cell can be greatly improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a negative electrode sheet and a lithium ion battery including the negative electrode sheet. Background technique [0002] At present, the global energy problem is becoming more and more serious, and the technological development of clean and renewable energy is imminent. Lithium-ion batteries have been widely used due to their high energy density, long cycle life, no memory effect, and environmental friendliness. However, in order to adapt to the continuous development of the new energy market, the development of lithium-ion batteries with higher capacity, higher energy density and longer life has become the focus of attention. [0003] In recent years, alloys and their composite materials with high capacity have aroused widespread interest of researchers, such as alloy materials Si, Ge, P, etc., oxides SiO 2 , SnO 2 , Fe 2 o 3 、Co 3 o 4 etc., su...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/66H01M4/134H01M4/1395H01M4/38H01M4/587H01M4/62H01M4/74H01M10/0525
CPCH01M4/661H01M4/742H01M4/386H01M4/587H01M4/628H01M4/134H01M4/1395H01M10/0525H01M2004/027Y02E60/10
Inventor 欧长志彭冲李俊义徐延铭
Owner ZHUHAI COSMX BATTERY CO LTD
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