Preparation method for silicon-carbon composite negative electrode material

A negative electrode material, silicon-carbon composite technology, applied in the direction of battery electrodes, electrical components, electrochemical generators, etc., can solve the problems of low strength of carbon cracked by organic matter, no fundamental improvement in material performance, and reduced capacity of composite materials. Achieve the effects of improving electrochemical performance and cycle performance, simple and environmentally friendly preparation method, and excellent cycle performance

Inactive Publication Date: 2017-08-04
SHAANXI COAL & CHEM TECH INST +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the silicon material will have a serious volume expansion effect in the process of deintercalating lithium, and the expansion rate is as high as 300%, which will cause the battery material to pulverize and fall off during the charging and discharging process, causing the battery capacity to rapidly decay
In order to solve the problem of powdering of silicon materials in the process of charging and discharging, researchers proposed to nano-silicon, because nano-silicon can reduce the volume change of materials and reduce the degree of powdering of electrodes, but nano-silicon materials are easy to agglomerate, making the material performance in the The application process has not been fundamentally improved
[0005] Researchers proposed to adopt the method of nano-silicon-carbon composite, which alleviated the problem of powdering and shedding of electrode materials to a certain extent, but because organic matter could not completely cover graphite and silicon, and the bonding between materials was not tight enough, after multiple charging After the discharge cycle, the capacity still has obvious attenuation, and the material still has serious pulverization.
Even though the organic matter can completely cover the nano-silicon through the existing technical means, the strength of the organic matter to crack carbon is not high, so that the content of the organic matter is too high and the capacity of the composite material is reduced, and the content of the organic matter is too low to effectively limit the charge and discharge process of the nano-silicon. The phenomenon of volume expansion, still does not improve the overall performance of the battery

Method used

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  • Preparation method for silicon-carbon composite negative electrode material
  • Preparation method for silicon-carbon composite negative electrode material
  • Preparation method for silicon-carbon composite negative electrode material

Examples

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Embodiment 1

[0030] A method for preparing a silicon-carbon composite negative electrode material of the present invention, comprising the following steps:

[0031] (1) Disperse nano-silicon spherical particles with a particle size of less than 90nm, natural graphite with a particle size of 1-5 μm, and pitch with a particle size of less than 50 μm at a mass ratio of 15:75:12.5, respectively, and mix them (the pitch is converted at 40% (calculated for pyrolysis carbon), heat the mixture to 80°C and stir it into a slurry with a solid content of 95% and then dry it, and heat the dried material to 150°C to melt for 4 hours (150°C is higher than the softening point of the bitumen used), so that The organic matter is in a liquid state with good fluidity, which can closely contact and bond with silicon and graphite. After cooling and drying, it is ground into a powder, and slowly heated to 450°C at a rate of 5°C / min in an argon atmosphere for 3 hours. Carry out low-temperature carbonization to ob...

Embodiment 2

[0036] A method for preparing a silicon-carbon composite negative electrode material of the present invention, comprising the following steps:

[0037](1) Disperse nano-silicon wires with a diameter of less than 90nm, artificial graphite with a particle size of 1-5 μm, and phenolic resin with a particle size of less than 50 μm at a mass ratio of 15:75:10, respectively, and mix them (the phenolic resin is converted at 40% (calculated for pyrolysis carbon), heat the mixture to 80°C and stir it into a slurry with a solid content of 95% and then dry it, heat the dried material to 120°C and melt for 4 hours (120°C is higher than the softening point of the phenolic resin used), Make the organic matter in a liquid state with good fluidity, which can be closely contacted and bonded with silicon and graphite. After cooling and drying, it is ground into a powder, and slowly heated up to 250°C at a rate of 5°C / min in an argon atmosphere. Carry out low-temperature carbonization for 3 hour...

Embodiment 3

[0041] A method for preparing a silicon-carbon composite negative electrode material of the present invention, comprising the following steps:

[0042] (1) Disperse nano silicon tubes with a diameter of less than 90nm, natural graphite with a particle size of 1-5 μm, and glucose with a particle size of less than 50 μm at a mass ratio of 15:75:15, respectively, and then mix them (wherein glucose is converted to cracked at 40% Carbon calculation), the mixture is heated to 80°C and stirred to form a slurry with a solid content of 95% and then dried, and the dried material is heated to 180°C to melt for 4 hours (180°C is higher than the softening point of the glucose used), so that the organic matter is Liquid with good fluidity, can closely contact and bond with silicon and graphite, cool and dry, grind into powder, and slowly heat up to 350°C at a rate of 5°C / min in an argon environment for 3 hours for low temperature Carbonization to obtain a primary coating material coated wit...

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Abstract

The invention discloses a preparation method for a silicon-carbon composite negative electrode material. The preparation method comprises the steps of performing dispersing on nanometer silicon, graphite and an organic matter separately and mixing in proportion; next, performing heating and drying and heating until the temperature reaches an organic matter softening point temperature or above, and performing fusing and binding and low-temperature carbonization to obtain an organic matter cracked carbon-coated primary coating material; performing dispersing on the organic matter and the primary coating material separately and mixing in proportion; and next, performing heating and drying and heating until the temperature reaches an organic matter softening point temperature or above, and performing fusing and coating and high-temperature carbonization to obtain an organic matter cracked carbon-coated secondary coating material, namely the silicon-carbon composite negative electrode material provided by the invention. The initial reversible capacity of the negative electrode material prepared by the method can reach 649mAh/g, and the capacity retention ratio after 50 cycles can be maintained at 85.36%, and quite excellent cycling performance is shown; and in addition, the preparation method has a simple and environment-friendly process, low energy loss, rich silicon and graphite raw material resource, low cost and high safety, and is suitable for industrial production and use.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion battery negative electrode materials, and in particular relates to a preparation method of a silicon-carbon composite negative electrode material. Background technique [0002] Since Sony Corporation of Japan developed the first generation of lithium-ion batteries in 1990 and successfully industrialized them, lithium-ion batteries have been developed for more than 20 years. Lithium-ion batteries are currently used in mobile electronic devices such as mobile phones, portable electric tools, new energy vehicles, and energy storage power stations. [0003] At present, commercial lithium-ion battery anode materials mainly use artificial graphite and natural graphite. Graphite materials have the advantages of small volume expansion coefficient, high coulombic efficiency and excellent cycle performance during battery charging and discharging. However, the maximum theoretical capacity of graphite ma...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/62H01M10/0525
CPCH01M4/366H01M4/621H01M10/0525Y02E60/10
Inventor 范瑞娟杨阳田占元郭华军张大鹏王志兴沈晓辉杨勇曹国林周玉邵乐周融
Owner SHAANXI COAL & CHEM TECH INST
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