Negative electrode binder, preparation method thereof, and preparation method of negative electrode sheet

A negative pole piece and binder technology, applied in structural parts, battery electrodes, electrochemical generators, etc., can solve the problems of lack of transmission channels for lithium ions, increased polarization of power batteries, power performance attenuation, etc., to increase transmission Channel, extended transmission channel, long cycle life effect

Active Publication Date: 2020-09-15
ZHUHAI COSMX BATTERY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the negative electrode binder used in the existing power lithium-ion batteries cannot form a liquid-locking network after the film is formed inside the pole piece, and the electrolyte exists in the pole piece in a free state.
As the cycle progresses, it is easy to form a "broken bridge" of the electrolyte, and the lithium ions lack a transmission channel, which leads to a substantial increase in the polarization of the power battery in the middle and late stages, resulting in rapid decay of power performance, a significant reduction in battery capacity retention, and cycle life. relatively insufficient

Method used

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  • Negative electrode binder, preparation method thereof, and preparation method of negative electrode sheet
  • Negative electrode binder, preparation method thereof, and preparation method of negative electrode sheet

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preparation example Construction

[0020] The preparation method of the negative electrode binder of the present invention is as follows: the acrylate monomer is added to the aqueous solution, the mass ratio of the acrylate monomer to the aqueous solution is 1:1 to 1:5, and the content of the emulsifier in the aqueous solution is 0 to 10%. (mass percentage), adding an initiator to initiate a polymerization reaction to obtain a polymer-type binder emulsion with a solid content of 35-55 wt%. The initiator used is a conventional initiator, and the temperature when the initiator is added for the polymerization reaction does not exceed 50°C. When the temperature is too high, the reaction is likely to be too intense and cause agglomeration.

[0021] In the obtained negative electrode binder, monomers containing carboxyl groups account for 10-100% of the molar weight of all monomers, and the glass transition temperature of the binder is -25-130°C.

[0022] The acrylate monomer of the present invention can be acrylate ...

Embodiment 1

[0029] Preparation of binder: Add 300 parts by mass of deionized water and 100 parts by mass of acrylic acid to a three-port reactor equipped with a temperature sensor, nitrogen input pipe, and stirring paddle, stir evenly, raise the temperature to 50°C, and add 0.02 parts by mass of Potassium persulfate-sodium sulfite was used as an initiator and reacted for 2 hours to obtain a polyacrylic acid binder, wherein the molecular weight of polyacrylic acid was 1 million. Since the proportion of carboxyl-containing monomers in this embodiment is relatively high, it can be self-emulsified, so the aqueous solution The emulsifier content in is 0%. When the binder is a self-emulsifying binder, the aqueous solution can be all deionized water; when the binder is a non-self-emulsifying binder, the aqueous solution is deionized water containing an emulsifier;

[0030] Prepare the negative electrode sheet: mix the negative electrode material with 0.8 parts by mass of a crosslinking agent, us...

Embodiment 2

[0034] The difference between this example and Example 1 is that the acrylate monomers used in the preparation of the adhesive are acrylic acid and butyl acrylate, and 70 parts by mass of acrylic acid and 30 parts by mass of butyl acrylate are added to the three-port reactor After stirring evenly with 300 parts by mass of deionized water, the temperature was raised to 50° C., and 0.02 parts by mass of potassium persulfate-sodium sulfite was added as an initiator, and the binder was prepared after 2 hours of reaction.

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Abstract

The invention relates to a negative pole binder, a preparation method therefor and a preparation method for a negative pole piece. During the preparation of the negative pole binder, a binder emulsionwith the solid content of 35wt% to 55wt% is obtained through adding an acrylate monomer into an aqueous solution, and then, adding an initiator for a polymerization reaction, wherein the mass ratio of the acrylate monomer to the aqueous solution is 1: (1 to 1.5). During the preparation of the negative pole piece, the negative pole binder and a cross-linker are added into negative pole slurry, andthe binder and macromolecules in the cross-linker are cross-linked to form network structural units after the binder is cured, so that an electrolyte cannot be in a free form, thus, more storage space is provided for the electrolyte, the electrolyte preserving volume is increased, the ionic conductivity is high, the high-power rapid charging and discharging of lithium-ion batteries can be achieved, and the power performance and cycle performance of the lithium-ion batteries are improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a negative electrode binder of lithium ion batteries and a preparation method thereof, and a preparation method of a negative electrode sheet using the negative electrode binder. Background technique [0002] With the development of technology, electric vehicles have gradually entered the market. Judging from the current situation of the domestic market, the double credit policy implemented in 2019 will be a huge test for many car companies. Although car companies are currently actively promoting electrification, due to cost and technical issues, the popularization of new energy vehicles is still difficult to achieve in a short period of time. In 2016, the penetration rate of new energy passenger vehicles in my country was only 1.4%. It is difficult for most car companies to meet the national carbon emission standards in a short period of time. The 48V m...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08F120/06C08F220/06C08F220/18C08F220/14H01M4/139H01M4/62H01M10/0525
CPCC08F120/06C08F220/06H01M4/139H01M4/622H01M10/0525C08F220/1804C08F220/14Y02E60/10
Inventor 申红光李俊义彭冲徐延铭
Owner ZHUHAI COSMX BATTERY CO LTD
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