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Method for producing lithium cell silicon carbon negative pole material and produced silicon carbon negative pole material

A negative electrode material, lithium battery technology, applied in battery electrodes, circuits, electrical components, etc., can solve the problems of limited improvement, material cycle performance can not meet the needs and other problems, to extend the decay speed, improve cycle performance, small particle size Effect

Inactive Publication Date: 2008-08-20
SHENZHEN BAK BATTERY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For example, magnetron sputtering or chemical deposition is used to deposit silicon films on current collectors, chemical vapor deposition is used to deposit nano-silicon films on graphite surfaces, nano-Si-Ni alloys are used, and nano-silicon-carbon composite materials are produced by high-energy mechanical ball milling. Or use silicon powder with an average particle size of 80nm or nano-silicon wires (15nm in diameter and hundreds of nanometers in length) to make silicon-carbon composite materials. These methods can indeed improve the cycle performance of silicon to a certain extent, but the degree of improvement Limited, the cycle performance of the material still cannot meet the needs

Method used

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Examples

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preparation example Construction

[0022] In order to effectively prolong the attenuation speed of the silicon-carbon material and improve the cycle performance of the silicon-carbon material, the invention provides a method for preparing a silicon-carbon negative electrode material, which comprises the following steps:

[0023] A. Dissolve the asphalt in a certain amount of asphalt solvent under stirring conditions to completely dissolve the asphalt. The solvent used may be pyridine, tetrahydrofuran / acetone mixed solution mixed at a volume ratio of 1:1, carbon disulfide or toluene. There is no specific requirement for the amount of solvent used, and the principle is to ensure that the asphalt and the subsequent addition of nano-silica powder and graphite can be fully dispersed without wasting.

[0024] B. Add an appropriate amount of nano-silica powder to the above solution to make it fully dispersed, such as dispersing through strong stirring and ultrasound, so that the nano-silica powder is evenly dispersed ...

Embodiment 1

[0033] Dissolve high-temperature pitch in carbon disulfide under stirring conditions, then add silicon powder (the particle size of silicon is 30nm, of which silicon powder: 10 parts, graphite: 84 parts, pitch 6 parts), and make it uniformly dispersed by stirring and ultrasonic treatment . Then add spherical graphite and stir evenly, put the above slurry on the top of a 60°C water bath to evaporate part of the solvent, and then transfer it to an oven for drying. Finally, carbonization is carried out under a nitrogen atmosphere, the heating rate is 2°C / min, the temperature is raised to 1000°C, and the temperature is kept for two hours. After cooling down to room temperature, pass through a 200-mesh sieve to obtain graphite negative electrode material.

[0034] With the negative electrode material that above-mentioned making is positive pole, lithium sheet is counter electrode, electrolyte is the LiPF of 1M EC / DMC (Vol 1: 1) solution, diaphragm paper is polyethylene, polypropyl...

Embodiment 2

[0036] This embodiment is basically the same as Example 1, except that the above-mentioned materials are added into the carbon disulfide solvent impregnated with asphalt and stirred evenly (the amount of asphalt used here is the same as that used in Example 1), and the solvent is dried Afterwards, carbonize again, and the carbonization system is the same as above, and the resulting material is passed through a 200-mesh sieve to make a button battery.

[0037] It is measured that the initial efficiency of the silicon carbon material is 84.22%, the reversible capacity is 454mAh / g, the reversible capacity after 300 cycles is 426.76mAh / g, and the cycle retention rate relative to the initial discharge capacity is 94%.

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Abstract

The invention discloses a method used to prepare silicon and carbon cathode material for lithium battery, which mixes and then carbonizes bitumastic solution, NM silica flour and spherical graphite. The invention also discloses a silicon and carbon cathode material prepared with the method. The method of the invention can effectively prolong the decay rate of the silicon and carbon cathode material and improve the cycle performance of the silicon and carbon cathode material.

Description

technical field [0001] The invention relates to a method for preparing a negative electrode material for a battery and the prepared negative electrode material, in particular to a method for preparing a silicon carbon negative electrode material for a lithium ion battery, and a nanometer silicon carbon negative electrode material prepared by the method. Background technique [0002] Graphite anode materials have been widely used in the production of lithium-ion batteries due to their high cycle efficiency and good cycle performance. However, its lithium storage capacity is low, the theoretical specific capacity is 372mAh / g, and the lithium intercalation potential is close to that of metal lithium, which poses a safety hazard during high-rate charging. Therefore, the development of new negative electrode materials has become the key to improving the performance of lithium-ion batteries. The research on capacity negative electrode materials mainly focuses on metals such as Si,...

Claims

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Application Information

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IPC IPC(8): C01B31/02H01M4/38
CPCY02E60/10
Inventor 骆兆军樊栋栋肖斌孙定元
Owner SHENZHEN BAK BATTERY CO LTD
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