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KR-20260062814-A - BINDER COMPOSITION FOR NON-AQUEOUS SECONDARY BATTERY NEGATIVE ELECTRODE, METHOD FOR PRODUCING BINDER COMPOSITION FOR NON-AQUEOUS SECONDARY BATTERY NEGATIVE ELECTRODE, COMPOSITION FOR NON-AQUEOUS SECONDARY BATTERY NEGATIVE ELECTRODE, NON-AQUEOUS SECONDARY BATTERY NEGATIVE ELECTRODE AND NON-AQUEOUS SECONDARY BATTERY

KR20260062814AKR 20260062814 AKR20260062814 AKR 20260062814AKR-20260062814-A

Abstract

(Problem) To provide a binder composition for a non-aqueous secondary battery negative electrode capable of forming a secondary battery having excellent elastic deformation characteristics and film-forming properties that can follow the volume change of the active material, as well as excellent durability against the electrolyte (electrolyte resistance) and excellent battery characteristics such as charge-discharge efficiency and capacity retention rate. (Solution) A binder composition for a non-aqueous secondary battery negative electrode comprising a core-shell type particle (A) having a shell portion made of a polymer (a1) and a core portion made of a polymer (a2), and an aqueous medium (B), wherein the polymer (a1) contains a structural unit derived from a reactive emulsifier, a structural unit derived from a vinyl monomer having an acidic group, and a structural unit derived from a (meth)acrylic acid ester monomer, and the polymer (a2) contains a structural unit derived from a conjugated diene monomer and a structural unit derived from an aromatic vinyl monomer.

Inventors

  • 마쓰오카 류이치
  • 야마모토 신야
  • 오무라 료스케

Assignees

  • 디아이씨 가부시끼가이샤

Dates

Publication Date
20260507
Application Date
20250722
Priority Date
20241029

Claims (16)

  1. A binder composition for a non-aqueous secondary battery negative electrode comprising a core-shell type particle (A) having a shell portion made of a polymer (a1) and a core portion made of a polymer (a2), and an aqueous medium (B). The above polymer (a1) contains a structural unit derived from a reactive emulsifier, a structural unit derived from a vinyl monomer having an acidic group, and a structural unit derived from a (meth)acrylic acid ester monomer, and A binder composition for a non-aqueous secondary battery negative electrode, wherein the above polymer (a2) contains a structural unit derived from a conjugated diene monomer and a structural unit derived from an aromatic vinyl monomer.
  2. In claim 1, A binder composition for a non-aqueous secondary battery negative electrode, wherein the above-mentioned reactive emulsifier is an emulsifier having an ethylenically unsaturated group.
  3. In claim 1, A binder composition for a non-aqueous secondary battery negative electrode, wherein the content of a structural unit derived from the reactive emulsifier, relative to the total amount excluding the structural unit derived from the reactive emulsifier from the unit constituting the polymer (a1), is 0.01 mass% or more and 3 mass% or less.
  4. In claim 1, A binder composition for a non-aqueous secondary battery negative electrode, wherein the content of a structural unit derived from a vinyl monomer having an acidic group, relative to the total amount excluding the structural unit derived from the reactive emulsifier from the unit constituting the polymer (a1), is 0.1 mass% or more and 10 mass% or less.
  5. In claim 1, A binder composition for a non-aqueous secondary battery negative electrode, wherein the above polymer (a1) further contains structural units derived from aromatic vinyl monomers.
  6. In claim 1, A binder composition for a non-aqueous secondary battery negative electrode, wherein the above polymer (a1) further contains a structural unit derived from a vinyl monomer having an amide group.
  7. In claim 1, A binder composition for a non-aqueous secondary battery negative electrode, wherein the above-mentioned conjugated diene monomer contains isoprene.
  8. In claim 1, A binder composition for a non-aqueous secondary battery negative electrode, wherein the above polymer (a2) further contains a structural unit derived from a vinyl monomer having a cyano group.
  9. In claim 8, A binder composition for a non-aqueous secondary battery negative electrode, wherein the content of a structural unit derived from a vinyl monomer having a cyano group, relative to the total amount of the unit constituting the polymer (a2), is 0.1 mass% or more and 10 mass% or less.
  10. In claim 1, A binder composition for a non-aqueous secondary battery negative electrode, wherein the above polymer (a2) does not contain structural units derived from vinyl monomers having acidic groups.
  11. In claim 1, A binder composition for a non-aqueous secondary battery negative electrode, wherein the above polymer (a2) does not contain structural units derived from fluorine-containing monomers.
  12. In claim 1, A binder composition for a non-aqueous secondary battery negative electrode, wherein X [mass%] is the content of the polymer (a1) in the core-shell type particle (A) and Y [mass%] is the content of the polymer (a2) in the core-shell type particle (A), and X:Y is 5:95 to 99:1.
  13. A method for manufacturing a binder composition for a non-aqueous secondary battery negative electrode comprising a core-shell type particle (A) having a shell portion made of a polymer (a1) and a core portion made of a polymer (a2), and an aqueous medium (B). A shell-forming process for forming polymer particles that form the shell portion, which are composed of the polymer (a1), by polymerizing a vinyl monomer having an acidic group and a (meth)acrylic acid ester monomer in the presence of a reactive emulsifier in the above aqueous medium (B); A method for manufacturing a binder composition for a non-aqueous secondary battery negative electrode, comprising a core forming process in which a core portion is formed by polymerizing a conjugated diene monomer and an aromatic vinyl monomer using the polymer particles as a reaction field to form the core portion made of the polymer (a2) inside the polymer particles.
  14. A composition for a non-aqueous secondary battery negative electrode comprising a negative electrode active material and a binder composition for a non-aqueous secondary battery negative electrode described in any one of claims 1 to 12.
  15. A non-aqueous secondary battery negative electrode having a negative electrode layer formed using the composition for a non-aqueous secondary battery negative electrode described in claim 14.
  16. A non-aqueous secondary battery comprising a negative electrode, a positive electrode, an electrolyte, and a separator as described in claim 15.

Description

Binder composition for a non-aqueous secondary battery negative electrode, method for producing a binder composition for a non-aqueous secondary battery negative electrode, composition for a non-aqueous secondary battery negative electrode, non-aqueous secondary battery negative electrode and non-aqueous secondary battery {BINDER COMPOSITION FOR NON-AQUEOUS SECONDARY BATTERY NEGATIVE ELECTRODE, METHOD FOR PRODUCING BINDER COMPOSITION FOR NON-AQUEOUS SECONDARY BATTERY NEGATIVE ELECTRODE, COMPOSITION FOR NON-AQUEOUS SECONDARY BATTERY NEGATIVE ELECTRODE, NON-AQUEOUS SECONDARY BATTERY NEGATIVE ELECTRODE AND NON-AQUEOUS SECONDARY BATTERY} The present invention relates to a binder composition for a non-aqueous secondary battery negative electrode, a method for manufacturing a binder composition for a non-aqueous secondary battery negative electrode, a composition for a non-aqueous secondary battery negative electrode, a non-aqueous secondary battery negative electrode, and a non-aqueous secondary battery. Non-aqueous secondary batteries (non-aqueous electrolyte secondary batteries), such as lithium-ion secondary batteries, are rapidly expanding their applications in hybrid vehicles, electric vehicles, and home storage batteries by leveraging their characteristics of high energy density and the ability to perform repeated charging and discharging. Furthermore, with the recent advancements in the performance and miniaturization of various portable electronic and communication devices, there is a growing demand for secondary batteries that are small, lightweight, have higher capacity, and have improved various battery characteristics such as cycle characteristics and discharge rate characteristics. Consequently, improvements to various battery components, such as electrodes, are being considered to further enhance the performance of non-aqueous secondary batteries. A negative electrode for a non-aqueous secondary battery typically comprises a current collector and an electrode material layer (negative electrode material layer) formed on the current collector. This negative electrode material layer is formed using a negative electrode composition in the form of a slurry, for example, in which a composition including a negative electrode active material and a binder (binding material) is dispersed in a dispersion medium. As one of the methods to increase the capacity of non-aqueous secondary batteries, it is being considered to apply silicon-containing active materials (silicon-based active materials), which have a higher lithium absorption capacity than conventional graphite-based active materials, as negative electrode active materials. Since silicon-containing active materials undergo significant volume changes due to lithium absorption and release, the negative electrode layer expands and contracts violently during charging and discharging. As a result, there is a problem in that the cycle characteristics of the secondary battery deteriorate due to a decrease in electron conductivity between negative electrode active materials, isolation of the silicon-containing active material within the negative electrode layer, and blockage of the conductive path between the negative electrode active material and the current collector. Regarding this problem, for example, in Patent Documents 1 and 2, it is considered that a cathode is prepared using a cathode slurry comprising as a binder both a (meth)acrylic acid-based polymer (PAA) with excellent elastic deformation properties capable of following volume changes of silicon-containing active materials and a styrene-butadiene copolymer (SBR) with excellent adhesion to the current collector and binding properties between active materials. Embodiments of the present invention will be described in detail below. Additionally, in this specification, a numerical range indicated by "~" represents a range that includes the values described before and after "~" as the minimum and maximum values, respectively. 1. Binder composition for non-aqueous secondary battery negative electrodes The present invention is a binder composition for a non-aqueous secondary battery negative electrode comprising a core-shell type particle (A) having a shell portion made of a polymer (a1) and a core portion made of a polymer (a2), and an aqueous medium (B), wherein the polymer (a1) contains a structural unit derived from a reactive emulsifier, a structural unit derived from a vinyl monomer having an acidic group, and a structural unit derived from a (meth)acrylic acid ester monomer, and the polymer (a2) contains a structural unit derived from a conjugated diene monomer and a structural unit derived from an aromatic vinyl monomer (hereinafter also simply referred to as "Binder composition for a negative electrode of the present invention 1"). The cathode binder composition 1 of the present invention is a water-based binder composition in which a binder (binding material) is dispersed in an aqueous medium (