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Binder and lithium ion battery containing same

A lithium-ion battery and binder technology, applied in secondary batteries, battery electrodes, circuits, etc., can solve the problems of poor processing performance of pole pieces, limited battery cycle life, failure to fully cover pole pieces, etc., to achieve Low-temperature performance improvement, expansion rate suppression, and effects of low expansion rate

Active Publication Date: 2021-01-05
ZHUHAI COSMX BATTERY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Silicon-based negative electrode binders mostly use aqueous polymers with a higher glass transition temperature, which can inhibit the expansion of silicon negative electrodes to a certain extent, but because the polymer is too rigid and inelastic, the processability of the pole piece is not good, and silicon The negative electrode cannot be reversibly recovered after swelling, and the cycle life of the battery is still limited
Although the combination of general SBR emulsion (particle size about 150-200nm) has some improvement, the effect of SBR emulsion particles on the pole piece is only point contact, and the pole piece cannot be fully covered.

Method used

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  • Binder and lithium ion battery containing same
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  • Binder and lithium ion battery containing same

Examples

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preparation example Construction

[0056] [Preparation method of cross-linked polymer]

[0057] As previously mentioned, the present invention also provides a method for preparing the above-mentioned cross-linked polymer, the method comprising the steps of:

[0058] (1) Make monomer A, monomer B and monomer C polymerize in the solvent system;

[0059] (2) After the completion of the polymerization reaction, adjust the pH value of the system, optionally adding or not adding diamine substances to obtain the cross-linked polymer;

[0060] Wherein, the monomer A, monomer B, monomer C and diamines have the meanings as described above.

[0061] According to an embodiment of the present invention, the mass ratio of monomer A, monomer B and monomer C is (6-8):(1.95-4):(0.001-0.4), for example (6.5-7.5): (2.2~3.5): (0.005~0.3).

[0062] According to an embodiment of the present invention, the solvent in the solvent system is water, such as deionized water.

[0063] According to the embodiment of the present inventio...

Embodiment 1

[0139] Preparation of cross-linked soluble polymers:

[0140] (1) Take 10 parts by mass of hydroxyethyl acrylate (monomer A), 0.2 parts by mass of N-methylol acrylamide (monomer C), and 2.5 parts by mass of acrylic acid (monomer B) to 200 parts by mass In deionized water, 800rpm mechanical stirring, nitrogen gas was introduced, the temperature was raised to 40°C, kept for 30min, 0.05 parts by mass of ammonium persulfate and 0.05 parts by mass of tetramethylethylenediamine were added, and reacted for 12 hours.

[0141] (2) Prepare a lithium hydroxide aqueous solution with a concentration of 5wt%, dropwise add it to the reaction system of step (1), adjust the pH to 7, and continue stirring for 2 hours to obtain a cross-linked soluble polymer with a viscosity of 8000mPa·s.

[0142] Each monomer is converted substantially completely, and the prepared polymer has a cross-linked structure of -A-B-C-.

[0143] The solid content of the prepared polymer was 6 wt%, and the weight avera...

Embodiment 2

[0152] Other operations are the same as in Example 1, and the difference is only that the cross-linked soluble polymer is prepared as follows:

[0153] (1) Add 10 parts by mass of hydroxypropyl acrylate, 0.3 parts by mass of N-methylolacrylamide, and 3 parts by mass of acrylic acid to 200 parts by mass of deionized water, stir mechanically at 800 rpm, feed nitrogen, and heat up to 40°C, keep warm for 30min, add 0.05 parts by mass of ammonium persulfate and 0.05 parts by mass of sodium bisulfite, and react for 12 hours.

[0154] (2) be prepared into a lithium hydroxide aqueous solution with a concentration of 5 wt%, dropwise added to the reaction system of step (1), adjust the pH to 7, and continue stirring for 2 hours to obtain a cross-linked soluble polymer with a viscosity of 8700mPa·s , the solid content is 5.8wt%, and the weight average molecular weight is about 650,000.

[0155] The above adhesive was tested, its glass transition temperature was 37°C, and its electrical ...

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Abstract

The invention discloses a binder and a lithium ion battery containing the same. The binder comprises a cross-linked polymer of which the structural formula is -A-B-C, wherein a chain segment A is provided by a monomer A, a chain segment B is provided by a monomer B, and a chain segment C is at least provided by a monomer C; wherein the monomer A is a polymer monomer endowing low glass transition temperature, the monomer B is a hydrophilic functional monomer, and the monomer C is a crosslinking monomer. The polymer has a low glass transition temperature and forms the binder in combination withan SBR emulsion. When the binder is applied to a silicon-based negative electrode, the cycle performance of the lithium ion battery is obviously improved, so that the cycle life of the lithium ion battery is prolonged.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, in particular to the field of binders for lithium ion batteries, in particular to a binder and a lithium ion battery containing the binder. Background technique [0002] As a kind of polymer, the binder in lithium-ion batteries not only plays the role of bonding between the active material layers, but also can be used for the bonding between the active material layer and the pole sheet substrate. It plays an important role and is one of the important components of the battery. [0003] The most widely used binder is polyvinylidene fluoride (PVDF), a copolymer of styrene and butadiene ((SBR). Silicon-based negative electrode binders mostly use aqueous polymers with higher glass transition temperatures. It can inhibit the expansion of the silicon negative electrode to a certain extent, but because the polymer is too rigid and inelastic, the processing performance of the pole piece is not good,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F220/20C08F220/58C08F220/06C08F220/28C08F220/54C08F220/56H01M4/62H01M10/0525
CPCC08F220/20H01M4/622H01M10/0525C08F220/58C08F220/06C08F220/286C08F220/54C08F220/56Y02E60/10
Inventor 储霖李素丽陈伟平李俊义
Owner ZHUHAI COSMX BATTERY CO LTD
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