US-20260128314-A1 - BINDER COMPRISING COPOLYMER COMPOSITION, NEGATIVE ELECTRODE FOR SECONDARY BATTERY COMPRISING SAME BINDER, AND SECONDARY BATTERY COMPRISING SAME NEGATIVE ELECTRODE

Abstract

The present invention relates to: a copolymer composition comprising a first copolymer comprising an acrylic acid-based monomer unit and an acrylamide-based monomer unit, and a second copolymer comprising a vinyl pyrrolidone-based unit, an acrylate-based monomer unit comprising a hydroxyl group, and an acrylamide-based monomer unit; and a negative electrode slurry, a negative electrode, and a secondary battery comprising the copolymer composition.

Inventors

• Hyeon-Ji GWON
• Ji-Hye Park
• So-Hyun Park
• Chan-Su Park
• Gyun-Tae KIM
• Min-ki Cho
• Chang-Beom Kim
• Se-Man KWON

Assignees

• HANSOL CHEMICAL CO.,LTD

Dates

Publication Date

20260507

Application Date

20231006

Priority Date

20221006

Claims (12)

1. 1 . A copolymer composition comprising: a first copolymer comprising an acrylic acid-based monomer unit and an acrylamide-based monomer unit; and a second copolymer comprising a vinyl pyrrolidone-based unit, an acrylate-based monomer unit containing a hydroxyl group, and an acrylamide-based monomer unit.
2. 2 . The copolymer composition of claim 1 , wherein the acrylic acid-based monomer unit of the first copolymer is formed by polymerizing an acrylic acid monomer, a methacrylic acid monomer, or a combination thereof, the acrylamide-based monomer unit of the first copolymer is formed by polymerizing an acrylamide monomer, a methacrylamide monomer, or a combination thereof, the acrylate-based monomer unit containing the hydroxyl group of the second copolymer is formed by polymerizing a 2-hydroxyethyl acrylate monomer, a 2-hydroxyethyl methacrylate monomer, or a combination thereof, and the acrylamide-based monomer unit of the second copolymer is formed by polymerizing an acrylamide monomer, a methacrylamide monomer, or a combination thereof.
3. 3 . The copolymer composition of claim 1 , wherein the first copolymer comprises 75 wt % or more and 95 wt % or less of the acrylic acid-based monomer unit and 5 wt % or more and 25 wt % or less of the acrylamide-based monomer unit, based on 100 wt % of the total weight of the first copolymer.
4. 4 . The copolymer composition of claim 1 , wherein the second copolymer comprises 30 wt % or more and 50 wt % or less of the vinyl pyrrolidone-based monomer unit, 30 wt % or more and 50 wt % or less of the acrylate-based monomer unit containing the hydroxyl group, and 10 wt % or more and 30 wt % or less of the acrylamide-based monomer unit, based on 100 wt % of the total weight of the second copolymer.
5. 5 . The copolymer composition of claim 1 , wherein the acrylic acid-based monomer unit of the first copolymer is formed by polymerizing an acrylic acid monomer and a methacrylic acid monomer in a weight ratio (weight of the acrylic acid monomer:weight of the methacrylic acid monomer) in a range of 2 to 10:1.
6. 6 . The copolymer composition of claim 1 , wherein the first copolymer comprises a monomer repeating unit represented by Formula 1 below, and the second copolymer comprises a monomer repeating unit represented by Formula 2 below, where in Formula 1, R and R′ are each independently hydrogen, an alkali metal, or a combination thereof, and a+b+c= 1, and in Formula 2, R″ is hydrogen, methyl, or a combination thereof, and x+y+z=1.
7. 7 . The copolymer composition of claim 1 , wherein the copolymer composition, based on 100 wt % of the total weight thereof, comprises 10 wt % or more and 90 wt % or less of the first copolymer and 10 wt % or more and 90 wt % or less of the second copolymer.
8. 8 . The copolymer composition of claim 1 , wherein the first copolymer is a random or block copolymer, and the second copolymer is a random or block copolymer.
9. 9 . The copolymer composition of claim 1 , wherein the first copolymer has a weight average molecular weight of 10,000 or more and 1,000,000 or less, and the second copolymer has a weight average molecular weight of 10,000 or more and 1,000,000 or less.
10. 10 . A negative electrode slurry comprising: the copolymer composition of claim 1 ; and a negative electrode active material.
11. 11 . A negative electrode comprising: a current collector; and a negative electrode active material layer comprising the copolymer composition of claim 1 , the negative electrode active material layer formed on the current collector.
12. 12 . (canceled)

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a National Stage of International patent application PCT/KR2023/015412, filed on Oct. 6, 2023, which claims priority to foreign Korean patent application No. KR 10-2022-0127868, filed on Oct. 6, 2022, the disclosures of which are incorporated by reference in their entireties. FIELD OF THE INVENTION The present disclosure relates to a copolymer composition usable as a binder, a slurry including the same, an electrode, and a secondary battery. BACKGROUND With high energy density, lithium secondary batteries are being used extensively in the fields of electrical, electronic, telecommunication, and computer industries. In addition, application fields of lithium secondary batteries are being expanded to high-capacity secondary batteries for hybrid vehicles, electric vehicles, and the like, in addition to small lithium secondary batteries for portable electronic devices. As such application fields expand, lithium secondary batteries are required to have longer life characteristics as well as higher capacity. One example of a method for making the capacity of lithium secondary batteries higher may involve using silicon atom-containing active materials in a negative electrode. The application of silicon atom-containing active materials, which involves intercalation and deintercalation of a higher amount of lithium than existing carbon-based active materials, may lead to the expectation of improved battery capacity. However, in the case of such silicon-containing active materials, the intercalation and deintercalation of lithium involve considerable volume changes. For this reason, negative electrode active material layers expand and contract significantly during charging and discharging. As a result, there have been the following problems: deterioration in conductivity between negative electrode active materials, blockage of a conductive path between negative electrode active materials and a current collector, and degradation of secondary battery cycling performance. However, various existing binders that have been developed (such as polyacrylic acid (PAA), PAA/carboxymethyl cellulose (CMC), Na-PAA, cross-linked PAA, alginate, and polyvinylalcohol (PVA)) lack adhesive strength or lack durability due to extremely brittle electrodes, meaning that such a problem described above regarding volume expansion is challenging to resolve under current circumstances. Therefore, a binder enabling the capacity retention rate of secondary batteries to be obtainable by addressing these problems is required. Document of Related Art Patent Document (Patent Document 1) Korean Patent Application Publication No. 10-2016-0024921 SUMMARY OF THE INVENTION Technical Problem Accordingly, the present disclosure aims to provide a copolymer composition having excellent flexibility. In addition, the present disclosure aims to provide a slurry composition having improved coating properties and rheological properties and an excellent ability to suppress electrode expansion, using the copolymer composition. Furthermore, the present disclosure aims to provide an electrode (especially a negative electrode) having excellent performance, the electrode to which the slurry composition is applied, and a secondary battery having excellent life characteristics (excellent capacity retention rate per cycle), the secondary battery including the electrode. However, the problems to be solved by the present application are not limited to the above description, and other problems can be clearly understood by those skilled in the art from the following description. Technical Solution In one aspect of the present application, a copolymer composition including: a first copolymer including an acrylic acid-based monomer unit and an acrylamide-based monomer unit; and a second copolymer including a vinyl pyrrolidone-based unit, an acrylate-based monomer unit containing a hydroxyl group, and an acrylamide-based monomer unit,is provided. In another aspect of the present application, a negative electrode slurry including: the copolymer composition; and a negative electrode active material,is provided. In a further aspect of the present application, a negative electrode including: a current collector; and a negative electrode active material layer including the copolymer composition, the negative electrode active material layer formed on the current collector, is provided. In yet another aspect of the present application, a secondary battery including the negative electrodeis provided. Advantageous Effects A copolymer composition of the present disclosure has excellent flexibility, thus improving the coating properties and rheological properties of a negative electrode slurry composition, and can suppress negative electrode expansion, resulting in improved secondary battery life. DESCRIPTION OF DRAWINGS FIG. 1 is a graph showing viscosity changes as a function of shear rates of negative electrode slurries of Exampl