Silicon-based composite material for negative active material, negative plate and lithium ion battery

A technology of silicon-based composite materials and negative electrode active materials, applied in battery electrodes, secondary batteries, and secondary battery repair/maintenance, etc., can solve the problems of severe cycle decay and low initial efficiency of silicon negative electrodes, and achieve slow cycle decay. , Improve the first effect and battery capacity, and promote the effect of regeneration

Inactive Publication Date: 2020-11-27
ZHUHAI COSMX POWER CO LTD
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AI Technical Summary

Problems solved by technology

In the present invention, by constructing a flexible and expandable electronic network and a stable and reproducible lithium ion transmission channel, and then using a slow-release cycle-expanding negative electrode active material, the problems of low first effect of the silicon negative electrode and severe cycle attenuation can be solved, which is for high The commercial application of silicon negative lithium-ion batteries with energy density is of great significance

Method used

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  • Silicon-based composite material for negative active material, negative plate and lithium ion battery
  • Silicon-based composite material for negative active material, negative plate and lithium ion battery
  • Silicon-based composite material for negative active material, negative plate and lithium ion battery

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preparation example Construction

[0070]

[0071] The present invention also provides a method for preparing the above-mentioned silicon-based composite material for the negative electrode active material, the method comprising the steps of:

[0072] The silicon-based composite material is prepared by mixing single-walled carbon nanotubes, an inorganic solid electrolyte, optionally a first conductive agent, and a silicon material, and heating to a temperature above the melting temperature of the inorganic solid electrolyte.

[0073]Wherein, during the heating process, the inorganic solid electrolyte will be melted, fully mixed with the single-walled carbon nanotubes, and optionally the first conductive agent, and coated on the surface of the silicon material particles, that is, a three-dimensional electrolyte is formed on the surface of the silicon material particles. A conductive network and a stable solid electrolyte coating, while the single-walled carbon nanotubes and optionally the first conductive agent...

Embodiment 1

[0127] (1) Preparation of negative electrode sheet

[0128] 0.95g of conductive carbon black SP, 0.05g of single-walled carbon nanotube SWCNT, 1g of Li 3 Mix OCl and 98g of SiO evenly, heat to 300°C, the molten Li 3 OCl can combine SP, SWCNT and Li 3 OCl is uniformly coated on the surface of SiO particles, and a silicon composite material is prepared.

[0129]12g of the prepared silicon composite material was mixed with 84g of graphite, then 2g of conductive agent SP, 2g of binder PVDF and solvent NMP were added, and stirred for 2 hours to prepare a negative electrode slurry with a solid content of 50wt%. The negative electrode slurry is evenly coated on both sides of the copper foil, dried and compacted by a roller press to obtain a negative electrode sheet.

[0130] (2) Preparation of positive electrode sheet

[0131] Mix 95g of positive electrode active material ternary nickel-cobalt-manganese NCM, 2g of binder PVDF and 3g of conductive carbon black as a conductive agen...

Embodiment 2

[0135] The difference from Example 1 is in step (1):

[0136] 17g of a 4% SWCNT aqueous solution and 108g of a 1.5% polymer solid electrolyte CMC-Li (number average molecular weight of 50,000) aqueous solution were placed in a stirring tank and stirred for 60 minutes to prepare a SWCNT-CMC-Li mixed solution.

[0137] Take 32g of SWCNT-CMC-Li mixed solution and place it in a stirring tank, add 1g of conductive agent SP and 26g of deionized water, and stir for 60 minutes to prepare a conductive adhesive, then add 10g of SiO, and stir for 90 minutes to prepare a silicon composite material precursor .

[0138] The silicon composite material precursor prepared above was mixed with 88g graphite material, 65g SWCNT-CMC-Li mixed solution, 4g binder SBR and 27g deionized water, and stirred for 2h to prepare a negative electrode slurry with a solid content of 50wt%. The negative electrode slurry is evenly coated on both sides of the copper foil, dried and compacted by a roller press to...

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Abstract

The invention provides a silicon-based composite material for a negative active material, a negative plate and a lithium ion battery. The preparation method comprises the following steps: arranging single-walled carbon nanotubes distributed in a three-dimensional network shape and an optional first conductive agent in a solid electrolyte coating layer; a three-dimensional conductive network can beconstructed on the surfaces of silicon material particles. Due to the establishment of the three-dimensional conductive network, the electron transmission between the silicon material particles and between the silicon material particles and the graphite is enhanced. The smoothness of an electronic channel after silicon expansion is ensured. The electron transmission stability in the circulation process is improved. The utilization rate of silicon is increased, the first utilization rate of the silicon material is increased, the first effect and the battery capacity of a lithium ion battery containing the silicon-based composite material are improved, the SWCNT elasticity is large, the super mechanical property is 100 times that of steel, it is guaranteed that a conductive network is not changed when a silicon negative electrode expands during circulation, circulation attenuation is slowed down, and the circulation performance is improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a silicon-based composite material for negative electrode active materials, a negative electrode sheet and a lithium ion battery. Background technique [0002] At present, commercialized lithium-ion batteries use graphite as the negative electrode, which has the advantages of excellent energy density, considerable cycle life, and environmental friendliness, making lithium-ion batteries widely used in portable electronic products such as mobile phones and notebook computers and new energy vehicles. With the replacement of these products, the energy density of traditional lithium-ion batteries using graphite (theoretical gram capacity ~ 370mAh / g) as the negative electrode is stretched, and it is difficult to achieve a higher energy density breakthrough. [0003] In order to obtain lithium-ion batteries with higher energy density, silicon anodes with higher gram capaci...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525H01M10/0562H01M10/42C01B32/158C01B32/20
CPCH01M4/366H01M4/625H01M4/386H01M10/0525H01M10/0562H01M10/4235C01B32/158C01B32/20Y02E60/10
Inventor 田义军申红光王美丽靳玲玲李俊义
Owner ZHUHAI COSMX POWER CO LTD
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