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Lithium ion battery negative electrode material with nanometer silicon reserved in carbon shell and fabrication method and application of lithium ion battery negative electrode material

A technology of negative electrode material and production method, which is applied in the direction of battery electrodes, lithium batteries, negative electrodes, etc., can solve the problems of high cost, powdering and falling off of active materials, easy agglomeration of nano-silicon, and achieve the effect of avoiding the pretreatment process

Active Publication Date: 2019-07-26
HUNAN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the negative electrode materials of lithium batteries in commercial use are mainly carbon materials such as graphite, but the capacity of graphite negative electrode is very close to its theoretical capacity (372mAh / g), while silicon has a specific capacity as high as 4200mAh / g, which is an ideal high specific capacity. And a safe negative electrode material, silicon will have a volume change of 320% during the lithium intercalation and delithiation process, which often causes the active material to pulverize and fall off, and lose its charge and discharge characteristics
After years of research, through improvements such as nanonization, carbon coating, and structural design, it is basically possible to deal with the volume change of silicon in the process of charging and discharging lithium. Its cost is very high, and it has reached 200,000-300,000 / ton at present, and nano-silicon is easy to agglomerate, which further affects the dispersion of silicon-carbon anode materials
In general, the high cost of nano-silicon and its easy agglomeration and non-conductive properties restrict the industrialization process of silicon-carbon anode materials. Therefore, a low-cost method of using waste silicon powder from photovoltaic cutting to prepare nano-silicon for lithium batteries The manufacture of silicon carbon anode materials has become an urgent problem to be solved in the industry

Method used

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  • Lithium ion battery negative electrode material with nanometer silicon reserved in carbon shell and fabrication method and application of lithium ion battery negative electrode material
  • Lithium ion battery negative electrode material with nanometer silicon reserved in carbon shell and fabrication method and application of lithium ion battery negative electrode material

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Embodiment 1

[0039] The preparation method of the lithium battery silicon carbon negative electrode material of the present embodiment comprises the following steps:

[0040] (1) Press-filter the waste silicon powder produced during the diamond wire cutting process in the silicon wafer production process into a cake; the filter cake is composed of elemental silicon micropowder with a particle size of 1-3 μm, organic cooling liquid and water; according to the previous According to the experience in the industry, the organic residues in the filter cake, the proportions of water and elemental silicon micropowder are 5-10%, 40-50%, and 50-60% respectively; The solid content is between 10-20% to ensure that the heat in the subsequent oxidation process is absorbed by the solution, but does not overflow;

[0041] (2) Dissolving the filter cake in the step (1) in water, and estimating that the solid content of the elemental silicon powder is about 20%.

[0042] (3) Add potassium persulfate oxidiz...

Embodiment 2

[0051] The difference between this embodiment and embodiment 1 is that in step (2), the solid content of the elemental silicon micropowder in the solution is 10%, and the rest are the same.

[0052] Compared with the traditional lithium battery (graphite negative electrode material, the specific capacity is 372mAh / g), the lithium battery silicon carbon packaged by the present invention adopts the specific capacity and cycle performance of the material tested by the constant current charge and discharge method, and the test detection result is the specific capacity of the negative electrode material. The capacity is 1300mAh / g, which is 3 times the specific capacity of graphite anode materials. After 100 cycles, the specific capacity is stable at 1120mAh / g, without rapid decay.

Embodiment 3

[0054] The difference between this embodiment and embodiment 1 is that in step (4), the activating substance of the oxidizing agent in the solution is cobalt nitrate, and the rest are the same.

[0055] Compared with the traditional lithium battery (graphite negative electrode material, the specific capacity is 372mAh / g), the lithium battery silicon carbon packaged by the present invention adopts the specific capacity and cycle performance of the material tested by the constant current charge and discharge method, and the test detection result is the specific capacity of the negative electrode material. The capacity is 1300mAh / g, which is 3 times the specific capacity of graphite anode materials. After 100 cycles, the specific capacity is stable at 1120mAh / g, without rapid decay.

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Abstract

The invention relates to a lithium ion battery negative electrode material with nanometer silicon reserved in a carbon shell and fabrication method and application of the lithium ion battery negativeelectrode material. According to the method, waste single-crystal micro powder wrapped with an organic matter is oxidized to a composite with nanometer silicon embedded into silicon oxide in one stepby wet advance oxidization, and an expansion-resistant structure with the nanometer silicon reserved in a carbon layer is formed by the traditional steps of coating a carbon layer through carbonization and corroding to remove the silicon oxide. By the method, solid waste is eliminated, the environmental pollution is reduced, and the cost of the nanometer silicon which can be used for the lithium battery negative electrode material is greatly reduced.

Description

technical field [0001] The invention relates to a method for treating waste silicon powder coated with organic matter, in particular to a negative electrode material of a lithium battery in which nano-silicon remains in a carbon shell, and a production method and application thereof. Background technique [0002] Silicon is the material with the largest output and the widest application in the modern semiconductor industry. The main process of silicon wafer production is completed by mechanical processing steps such as crystal growth and crystal cutting. For example, silicon wafers in the photovoltaic industry are mainly composed of silicon ingot squares, truncation, edging, wire cutting and other steps. [0003] With the rapid development of the photovoltaic industry, the amount of silicon materials has expanded rapidly, and has now exceeded the amount used in the semiconductor field. In 2014, the amount of domestically produced high-purity polysilicon and imported polysil...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/052
CPCH01M4/366H01M4/386H01M4/625H01M4/628H01M10/052H01M2004/021H01M2004/027Y02E60/10
Inventor 吕铁铮
Owner HUNAN INST OF TECH
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