Method for modifying silicon-carbon composite negative electrode by asphalt modification process derivative

A technology of silicon-carbon composite and asphalt modification, applied in battery electrodes, nanotechnology for materials and surface science, electrical components, etc., can solve problems such as unsuitable for industrial production, broken silicon-based material structure, pulverization, etc. , to achieve the effect of improving Coulombic efficiency and cycle retention rate, smooth molecular decomposition and polymerization reaction, and reducing volatile gas escape

Active Publication Date: 2020-06-26
西安英纳吉科技有限公司
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  • Abstract
  • Description
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  • Application Information

AI Technical Summary

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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  • Method for modifying silicon-carbon composite negative electrode by asphalt modification process derivative
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  • Method for modifying silicon-carbon composite negative electrode by asphalt modification process derivative

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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. The invention particularly relates to a method for modifying a silicon-carbon composite negative electrode by an asphalt modification process derivative. The content of light components of the modified asphalt is low, the relative molecular mass is high, and the hydrocarbon ratio is greater than 1.5. The molecular decomposition polymerization reaction is gentle in the carbonization process, and volatile gas escape is greatly reduced, so that a higher coking value is achieved after carbonization, a compact asphalt nano-coated carbon layer with low pore defect degree is formed on the surfaces of nano-silicon and graphite, excessive active lithium ion consumption is avoided in the charging and discharging process of the modified asphalt coated silicon-carbon composite negative electrode material, and the first coulombic efficiency of the battery is remarkably improved. Besides, the compact asphalt nano-coated carbon layer with low pore defect degree can also play an effective role in buffering the volume expansion of the inner-layer silicon, so that the diving condition of the battery is obviously delayed, andthe coulombic efficiency and the cycle retention rate of the material are improved.

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 Applications(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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