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Negative electrode for power battery and power battery comprising same

A power battery and negative electrode technology, which is applied in the field of negative electrodes for power batteries, can solve the problems of reduced Coulombic efficiency, increased irreversible capacity for the first charge and discharge, and reduced battery life.

Inactive Publication Date: 2017-05-31
SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the formation of the SEI film is at the cost of consuming part of the lithium ions that can be deintercalated, which increases the irreversible capacity of the first charge and discharge and reduces the Coulombic efficiency. If the SEI film formed on the electrode surface is unstable, it will occur during the cycle. The process of "formation-rupture-reformation" of the SEI film will reduce the service life of the battery

Method used

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  • Negative electrode for power battery and power battery comprising same

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Embodiment 1

[0020] This embodiment provides a negative electrode for a power battery, including a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector. The negative electrode active material layer includes graphite and a silicon carbon material dispersed in the gaps of the graphite, The proportion of graphite is 50%, and the particle size of graphite is 0.5 μm-100 μm; the silicon-carbon material is a silicon material coated with a porous carbon layer, the thickness of the porous carbon layer is 5 μm-90 μm, and the mass ratio of the porous carbon layer to the silicon-carbon material The porosity of the porous carbon layer is 30%, and the porosity of the porous carbon layer is 45%.

[0021] The surface of the negative electrode active material layer is provided with a SEI-like film coating layer. In terms of mass percentage, the composition of the SEI-like film coating layer is: 80% amorphous car...

Embodiment 2

[0023] The difference with embodiment 1 is:

[0024] The negative electrode active material layer includes graphite and silicon-carbon material dispersed in the gaps of graphite. The proportion of graphite is 60%. The mass ratio of the layer to the silicon-carbon material is 20%, and the porosity of the porous carbon layer is 60%.

[0025] The composition of the SEI-like film coating layer is: 70% amorphous carbon, 10% lithium carbonate, 10% alkyl lithium carbonate, 9.3% lithium fluoride and 0.7% binder styrene-butadiene rubber, SEI-like The thickness of the film coating layer was 10 μm.

[0026] The rest are the same as in Embodiment 1, and will not be repeated here.

Embodiment 3

[0028] The difference with embodiment 1 is:

[0029] The negative electrode active material layer includes graphite and silicon-carbon material dispersed in the gaps of graphite, the proportion of graphite is 80%; the silicon-carbon material is a silicon material coated with a porous carbon layer, and the thickness of the porous carbon layer is 5 μm-90 μm. The mass ratio of the layer to the silicon-carbon material is 25%, and the porosity of the porous carbon layer is 30%.

[0030]The composition of the SEI-like film coating layer is: 50% amorphous carbon, 20% lithium carbonate, 18.5% alkyl lithium carbonate, 10% lithium fluoride and 1.5% binder sodium alginate, SEI-like The thickness of the film coating layer was 25 μm.

[0031] In the preparation method of the SEI-like film coating layer, deionized water is replaced by ethanol, spraying is replaced by transfer printing, and the temperature of heat treatment is 80°C.

[0032] The rest are the same as in Embodiment 1, and wi...

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Abstract

The invention belongs to the technical field of a power battery, and particularly relates to a negative electrode for the power battery. The negative electrode comprises a negative electrode current collector and a negative active substance layer, wherein the negative active substance layer is applied on a surface of the negative electrode current collector and comprises graphite and a composite material, the composite material is dispersed in gaps of the graphite and is a silicon carbon material and / or tin carbon material, the specific gravity of the graphite accounts for 10-100%, and a coating layer similar to a solid electrolyte interface film (SEI film) is arranged on a surface of the negative electrode current collector. Compared with the prior art, the negative electrode has the advantages that with the arrangement of the coating layer similar to the SEI film, the contact of an electrolyte and silicon particles / tin particles can be reduced, the negative electrode is protected, and meanwhile, the initial coulombic efficiency of a composite negative electrode can be improved. Interface modification on the negative electrode is proposed by the invention, the SEI film is simulated and constructed, the coulombic efficiency of the material and the interface compatibility of the electrolyte are improved, and the application of the silicon carbon material and the tin carbon material in the battery is promoted.

Description

technical field [0001] The invention belongs to the technical field of power batteries, and in particular relates to a negative electrode for a power battery and a power battery including the negative electrode. Background technique [0002] The urban climate is deteriorating and the smog pollution is serious, seriously endangering people's health. The development of new energy electric vehicles has become an inevitable choice to reduce urban pollution. The large-scale application of electric vehicles puts forward high requirements on the safety and energy density of lithium-ion power batteries. Lithium-ion batteries are widely used in various electronic products and electric vehicles due to their high energy density and long cycle life. However, at present, lithium-ion power batteries still use liquid electrolytes, which have strong thermal reactivity with the positive and negative electrodes, which can easily cause battery combustion and explosion; in addition, the energy...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M4/133H01M4/62H01M10/0525
CPCH01M4/133H01M4/366H01M4/386H01M4/387H01M4/587H01M4/628H01M10/0525H01M2004/027H01M2220/20Y02E60/10
Inventor 贺艳兵钱坤李喜林李懿洋罗丹游从辉李宝华杨全红康飞宇
Owner SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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