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A method for modifying silicon-carbon composite negative electrode with asphalt modified process derivatives

A silicon-carbon composite, asphalt modification technology, applied in battery electrodes, nanotechnology for materials and surface science, nanotechnology, etc., can solve the problems of unsuitable industrial production, broken silicon-based material structure, pulverization and other problems , to achieve the effects of improving Coulomb efficiency and cycle retention, smooth molecular decomposition and polymerization, and reduced volatile gas escape.

Active Publication Date: 2021-12-21
西安英纳吉科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Although the silicon-based negative electrode material has a high theoretical capacity, there are still technical barriers that need to be overcome in the actual use process. The main problems are: 1) The volume expansion after lithium intercalation reaches 400%, resulting in the structure of the silicon-based material being broken, pulverized, As a result, the electrode is inactivated; 2) The electronic conductivity is poor and cannot be used alone as a negative electrode material
However, this method is costly and complicated, and is not suitable for industrial production.

Method used

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  • A method for modifying silicon-carbon composite negative electrode with asphalt modified process derivatives
  • A method for modifying silicon-carbon composite negative electrode with asphalt modified process derivatives
  • A method for modifying silicon-carbon composite negative electrode with asphalt modified process derivatives

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Embodiment approach

[0028] A method for modifying silicon-carbon composite negative electrodes by asphalt modification process derivatives, the method is realized through the following steps:

[0029] Step 1. In step 1, the asphalt softening point is obtained by mixing any one or more of 80-280° C.; the non-polar solvent is an alkane (the molecular formula is C n h 2n+2 ), naphthenes (molecular formula is C n h 2n ), cycloalkene (molecular formula is C n h 2n-2 ), cycloalkynes (molecular formula is C n h 2n-4 )(5≤n≤16), monocyclic aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene, propylbenzene, isopropylbenzene, para-trimethylbenzene, mesitylene, mesitylene Any one or more non-polar mixed solvents among toluene, styrene, phenylacetylene) and aromatic compounds containing benzene rings (number of benzene rings≤2). The ratio of bitumen to non-polar solvent is 1:40-1:4.

[0030] Step 2, heating and stirring the asphalt mixed solution to accelerate the full ...

Embodiment 1

[0035] Step 1. Weigh 1 part of pitch with a softening point of 250°C and a particle size D50 of 1.8 μm, and uniformly disperse it in 40 parts of toluene solvent to obtain a pitch and toluene dispersion solution.

[0036] Step 2. Heat the asphalt and toluene dispersion to 50°C and stir at a speed of 300r / min for 3 hours to fully dissolve the asphalt in the toluene solvent to obtain toluene and asphalt dispersion;

[0037] Step 3. Suction filter the toluene and asphalt dispersion solution, and wash the undissolved asphalt with the toluene solution for several times until the filtrate no longer changes color, and obtain asphalt toluene insoluble matter;

[0038] Step 4, put 1 part of asphalt toluene insoluble matter, 1 part of D50 of 150nm nano-silicon, and 8 parts of D50 of 3 μm graphite into a ball mill for ball milling; the ball mill speed is 300rpm, the ball milling time is 3h, and the ball-to-material ratio is 10:1; Obtain the precursor of the pitch-coated silicon-carbon com...

Embodiment 2

[0051] Step 1. Weigh 1 part of asphalt with a softening point of 250°C and a particle size D50 of 1.8 μm, and uniformly disperse it in 40 parts of n-hexane solvent to obtain a mixed solution of asphalt and n-hexane.

[0052] Step 2. Heat the mixed solution of asphalt and n-hexane to 50°C, and stir at a speed of 300r / min for 3 hours to accelerate the dissolution of asphalt in n-hexane;

[0053] Step 3. Suction filter the asphalt dispersion solution, and wash the undissolved asphalt with n-hexane several times until the filtrate no longer changes color, and obtain the asphalt n-hexane insoluble matter;

[0054] Step 4. Put 1 part of asphalt n-hexane insoluble matter, 1 part of D50 of 150nm nano-silicon, and 8 parts of D50 of 3 μm graphite into a ball mill for ball milling; the speed of the ball mill is 300rpm, the ball milling time is 3h, and the ball-to-material ratio is 10:1 ; Obtain the precursor of pitch n-hexane insoluble matter coated silicon-carbon composite negative elec...

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Abstract

The invention relates to the technical field of lithium battery materials, in particular to a method for modifying silicon-carbon composite negative electrodes by asphalt modification process derivatives. The modified asphalt has a low content of light components, a relatively high molecular weight, and a carbon-hydrogen ratio greater than 1.5. During the carbonization process, the molecular decomposition and polymerization reaction is smooth, and the escape of volatile gases is greatly reduced. Therefore, it has a higher coking value after carbonization, and a pitch nano-coated carbon layer with dense and low pore defects is formed on the surface of nano-silicon and graphite. The stabilized pitch-coated silicon-carbon composite anode material can avoid excessive consumption of active lithium ions during charge and discharge, and significantly improve the first Coulombic efficiency of the battery; in addition, the dense, low-porosity nano-coated carbon layer can also be used It can effectively buffer the volume expansion of the inner layer silicon, significantly delay the occurrence of battery diving, and improve the Coulombic efficiency and cycle retention rate of the material.

Description

technical field [0001] The invention relates to the technical field of lithium battery materials, in particular to a method for modifying silicon-carbon composite negative electrodes by asphalt modification process derivatives. Background technique [0002] With the rapid development of new energy vehicles and portable electronic digital products, the market demand for high energy density lithium-ion batteries is increasingly urgent. The theoretical capacity of graphite, a traditional negative electrode material, is only 372mAh / g, which cannot meet the needs of high energy density lithium-ion batteries. In order to further increase the energy density of lithium batteries, new anode materials with higher specific capacities must be developed. The theoretical capacity of silicon is as high as 4200mAh / g, which is more than ten times the theoretical capacity of graphite. It has a low lithium intercalation potential, and the earth is rich in reserves (accounting for 25.8% of the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/38H01M4/62H01M10/052B82Y30/00B82Y40/00
CPCH01M4/386H01M4/625H01M4/628H01M10/052B82Y30/00B82Y40/00Y02E60/10
Inventor 刘婷马越
Owner 西安英纳吉科技有限公司
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