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A kind of silicon-carbon composite material for lithium ion battery and preparation method thereof

A technology of silicon-carbon composite materials and lithium-ion batteries, which is applied in battery electrodes, secondary batteries, circuits, etc., can solve problems such as limiting battery cycle performance, low battery Coulombic efficiency, and limiting material applications, so as to improve Coulombic efficiency and cycle performance, improved cycle performance, and improved Coulombic efficiency

Active Publication Date: 2021-06-01
BERZELIUS (NANJING) CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the large specific surface area of ​​nanonized silicon particles, the coulombic efficiency of the battery is very low, and during the cycle, the SEI on the surface of the silicon particles is repeatedly generated, resulting in a thicker SEI film on the surface, which blocks the conduction of electrons and causes the loss of particles. life, which limits the cycle performance of the battery
(2) Preparation of silicon materials with special nanostructures, such as silicon nanotubes, silicon nanowires, porous silicon, etc., but this method has high cost and low output, and is currently only suitable for laboratory research
[0013] Existing materials are mainly improved in the direction of small particles, but due to low Coulombic efficiency and poor cycle, the application of materials in lithium-ion batteries is limited

Method used

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  • A kind of silicon-carbon composite material for lithium ion battery and preparation method thereof
  • A kind of silicon-carbon composite material for lithium ion battery and preparation method thereof
  • A kind of silicon-carbon composite material for lithium ion battery and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0069] Take 1000g of micron amorphous silicon powder with a median particle size of 2 μm, add 2000g of deionized water, add 500g of sucrose, stir, dissolve and mix, weigh 50g of single-walled carbon nanotubes with a solid content of 0.4%, 50g of polyethylene Pyrrolidone, fully stirred with the above slurry, and mixed evenly. The slurry was spray-dried and granulated to obtain secondary particles with a median diameter of 9.6 μm. The spray-dried dry powder was heated at 600° C. for 10 hours in an argon inert atmosphere to carbonize the sucrose to obtain a silicon material in which spherical single-walled carbon nanotubes were tightly wound. Take 800 g of the above-mentioned spherical particles and 114 g of coal tar pitch, put them into a mechanical fusion machine, and perform high-speed fusion treatment at 1500 rpm for 30 minutes to obtain spherical silicon composite particles coated with coal tar pitch. The above materials were kept at 300°C for 2 hours in an argon inert atmo...

Embodiment 2

[0077] Take 1000g of micron crystalline silicon powder with a median particle size of 4.3 μm, add 2000g of ethanol, add 25g of glucose, stir, dissolve and mix, weigh 25g of single-walled carbon nanotubes with a solid content of 0.4%, 50g of polyvinylpyrrolidone, Stir well with the above slurry and mix evenly. The slurry was spray-dried and granulated to obtain secondary particles with a median diameter of 14 μm. The spray-dried dry powder was heated at 700° C. for 6 hours in an argon inert atmosphere to carbonize the sucrose to obtain a silicon composite material in which spherical single-walled carbon nanotubes were tightly wound. Take 800g of spherical silicon composite material, take 50g of petroleum asphalt passed through a 200-mesh sieve, and mechanically mix it with a VC mixer for 10 minutes. Under a nitrogen-protected atmosphere, raise the temperature of the equipment to 300°C while stirring, and continue stirring for 30 minutes. Then cool to room temperature. The abo...

Embodiment 3

[0081] Get 1000g of micron crystalline silicon powder whose median particle size is 8 μm, add 2000g of water, add 667g of sucrose, stir, dissolve and mix, take 400g of multi-walled carbon nanotubes with a solid content of 5%, 50g of polyvinylpyrrolidone, and The above slurry is fully stirred and mixed evenly. The slurry was spray-dried and granulated to obtain secondary particles with a median diameter of 48 μm. The spray-dried dry powder was heated at 800° C. for 2 hours in an argon inert atmosphere to carbonize the sucrose to obtain a silicon composite material in which spherical multi-walled carbon nanotubes were tightly wound. Sieve the above materials to obtain a spherical silicon-carbon composite material.

[0082] Take 90 parts of the above-mentioned silicon-carbon composite material, 6 parts of conductive additive, and 4 parts of binder, homogenize, coat, dry, and roll in an aqueous system to obtain a silicon-containing negative electrode sheet.

[0083]The half-cell...

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Abstract

The invention relates to a silicon-carbon composite material for lithium-ion batteries and a preparation method thereof. The silicon-carbon composite material is a spherical secondary particle; the secondary particle is composed of a silicon material, a long-range conductive additive and carbon ; In the secondary particles, the long-range conductive additive and the silicon material are uniformly dispersed; the median particle size of the silicon material primary particles is between 1 and 10 μm; the median particle size of the secondary particles is between 5 and 50 μm ; The surface of the secondary particle is coated with carbon layer or not coated with carbon. The silicon-carbon composite material prepared by the present invention shows high coulombic efficiency and capacity when used in lithium-ion batteries, and significantly improves the energy density, rate performance and cycle performance of lithium-ion batteries. The process of the present invention is simple and easy to realize industrial production .

Description

technical field [0001] The invention relates to the field of lithium-ion batteries, in particular to a silicon-carbon composite material for lithium-ion batteries and a preparation method thereof. Background technique [0002] Due to the rapid development and wide application of various portable electronic devices and electric vehicles in recent years, the demand for lithium-ion batteries with high energy density and long cycle life has become increasingly urgent. At present, the negative electrode material of commercial lithium-ion batteries is mainly graphite, but due to the low theoretical capacity (372mAh / g), the further improvement of the energy density of lithium-ion batteries is limited. Among many new lithium-ion battery anode materials, silicon anode materials have the advantage of high capacity that cannot be matched by other anode materials (Li 22 Si 5 , the theoretical lithium storage capacity is 4200mAh / g), which is more than 11 times the theoretical capacity ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/62H01M4/583H01M4/38H01M10/0525
CPCH01M4/362H01M4/366H01M4/386H01M4/583H01M4/621H01M4/625H01M10/0525Y02E60/10
Inventor 张和宝李喆叶兰罗姝王岑
Owner BERZELIUS (NANJING) CO LTD
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