Preparing method for silicon-carbon composite negative electrode material for lithium ion battery

A lithium-ion battery and silicon-carbon composite technology, applied in battery electrodes, nanotechnology for materials and surface science, secondary batteries, etc., can solve problems such as structural damage, uneven distribution of silicon materials, and easy agglomeration. Achieve the effects of reducing the possibility of agglomeration, improving the volume effect and increasing the tap density

Active Publication Date: 2015-12-30
CENT SOUTH UNIV +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the surface activity of nano-silicon is high. During the preparation of composite materials, nano-silicon has high surface activity and is prone to agglomeration, resulting in uneven distribution of silicon in the obtained material and limited improvement in cycle performance. Therefore, dispersants are generally used in the material preparation process.
In addition, the composite material obtained by simply mixing nano-silicon and graphite is not stable enough in structure, and the bonding ability of silicon and graphite is not good, so the structure is easily damaged during charging and discharging, and a large amount of organic carbon needs to be added to improve the structure. The stability of the material, although the specific capacity retention rate of the material during the charge-discharge cycle can be improved in the end, but the first Coulombic efficiency of the material will decrease

Method used

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  • Preparing method for silicon-carbon composite negative electrode material for lithium ion battery
  • Preparing method for silicon-carbon composite negative electrode material for lithium ion battery
  • Preparing method for silicon-carbon composite negative electrode material for lithium ion battery

Examples

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Embodiment 1

[0038] A method for preparing a silicon-carbon composite negative electrode material for a lithium-ion battery, comprising the following steps:

[0039] 1) Take 0.6g of nano-silicon and add it into 80mL of alcohol solution with a volume fraction of 50%, and ultrasonically disperse for 30 minutes to obtain a nano-silicon dispersion. Then add 5g of graphite flakes and 4g of sodium polyacrylate solution with a solid content of 5% into the nano-silicon dispersion, stir and mix evenly with magnetic force, and then disperse evenly by ultrasonication for 30 minutes. Then place the uniformly dispersed mixed solution in a water bath at a constant temperature of 70°C for water bath drying, then place the dried mixture in a tube furnace for carbonization under the protection of an inert gas, and heat it from room temperature to 700°C 3h, the silicon / flake graphite / organic carbon composite material was obtained.

[0040]2) Mix 1g of spherical graphite with 0.08g of coal tar pitch powder,...

Embodiment 2

[0051] A method for preparing a silicon-carbon composite negative electrode material for a lithium-ion battery, comprising the following steps:

[0052] 1) Take 0.6g of nano-silicon and add it into 50mL of deionized water, and ultrasonically disperse for 30min to obtain a nano-silicon dispersion. Then add 2.25g flake graphite to 150mL graphene oxide solution with a concentration of 1mg / mL and mix evenly, and then add 3g solid-containing 5% sodium polyacrylate solution into the nano-silicon dispersion, magnetically stir and mix evenly, and then Ultrasonic for 30min to disperse evenly. Then freeze-dry the uniformly dispersed mixed solution, and then place the dried mixture in a tube furnace under the protection of an inert gas from room temperature at a rate of 8 °C / min to 700 °C for 3 hours to obtain silicon / flaky graphite / Organic carbon composites.

[0053] 2) Mix 1g of spherical graphite with 0.1g of coal tar pitch powder and grind for 30min, then place it in a tube furnac...

Embodiment 3

[0063] A method for preparing a silicon-carbon composite negative electrode material for a lithium-ion battery, comprising the following steps:

[0064] 1) Take 0.6g of nano-silicon and add it into 100mL of alcohol solution with a volume fraction of 50%, and ultrasonically disperse for 30 minutes to obtain a nano-silicon dispersion. Then add 0.8g flake graphite and 8g polyacrylate emulsion with a solid content of 5% to the nano-silicon dispersion, stir and mix evenly by magnetic force, and then disperse evenly by ultrasonication for 30min. Then place the uniformly dispersed mixed solution in a water bath at a constant temperature of 70°C for water bath drying, and then place the dried mixture in a tube furnace under the protection of an inert gas from room temperature to 700°C for 3 hours to obtain silicon / flake graphite / amorphous carbon composite.

[0065] 2) Mix 2g of spherical graphite with 0.03g of coal tar pitch powder and grind for 30 minutes, then place it in a tub...

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Abstract

The invention discloses a preparing method for a silicon-carbon composite negative electrode material for a lithium ion battery. The preparing method includes the following steps that 1, flake graphite, a polymer solution and nanometer silicon dispersion liquid are evenly mixed, dried and carbonized in a protective atmosphere; 2, pitch and spherical graphite are mixed, ground, placed in an inert protective atmosphere, and subjected to heat treatment to obtain modified spherical graphite; 3, a binder, the modified spherical graphite and the mixed material obtained after carbonization in the step 1 are added into solvent, dispersed evenly and dried to obtain a precursor material; 4, the precursor material is carbonized to obtain the silicon-carbon composite negative electrode material. In the process of the preparing method, it is unnecessary to add special dispersant, nanometer silicon is evenly dispersed in the graphite by means of some ionic groups existing in the polymer solution and high viscosity, the polymer solution has certain stability, and the possibility of nanometer silicon aggregation in the drying process is reduced.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery materials, and in particular relates to a preparation method of a silicon-carbon composite negative electrode material for lithium-ion batteries. Background technique [0002] Lithium-ion batteries have the advantages of high energy density, high and stable working voltage, long cycle life and environmental protection, and are widely used in portable devices. With the rapid development of various electronic devices and electric vehicles, people have higher and higher requirements on the energy and cycle life of lithium-ion batteries. The negative electrode material is an important part of the battery. Together with the positive electrode material, it determines the key performance of the lithium-ion battery, such as cycle life, capacity and safety, and has become the focus of research in various countries. At present, the negative electrodes of commercialized lithium-ion batteries are mainly ca...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M4/62H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/366H01M4/386H01M4/587H01M4/621H01M4/622H01M10/0525Y02E60/10
Inventor 周融田占元郭华军范瑞娟王志兴冯皓周玉沈晓辉
Owner CENT SOUTH UNIV
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