Polymers, compositions, slurry for positive electrodes, positive electrodes, and secondary batteries

Abstract

To provide: a polymer capable of obtaining a slurry for a positive electrode which is a slurry having high solid content and excellent coating film forming properties and can prepare a battery having battery characteristics comparable to a battery produced using a conventional polymer; a composition comprising a polymer; a slurry for a positive electrode; a positive electrode; and a secondary battery.SOLUTION: There is provided a polymer in which when the steady flow viscosities measured under shear rates of 1S-1 and 10S-1 at 25°C are defined as ηX1 and ηX10 mPa S, as measured for a dispersion comprising 2 mass% of the polymer, 4 mass% of acetylene black and 94 mass% of N-methylpyrrolidone and the complex viscosities measured at angular frequencies of 1 rad / s and 10 rad / s at 25°C are defined as ηY1 and ηY10 mPa S, ηY1 / ηX1, as measured for the dispersion and ηY10 / ηX10 are 0.6 to 1.9 .

Claims

1. It is a polymer, A dispersion consisting of 2% by mass of the polymer, 4% by mass of acetylene black, and 94% by mass of N-methylpyrrolidone, with a shear rate of 1S at 25°C. －１ and 10S －１ The steady flow viscosity measured by η Ｘ１ η Ｘ１０ The complex viscosity of the dispersion, measured at 25°C at angular frequencies of 1 rad / s and 10 rad / s, is given by η (mPa·s). Ｙ１ η Ｙ１０ When expressed as mPa·S, η Ｙ１ / η Ｘ１ 、η Ｙ１０ / η Ｘ１０ is 0.6 to 1.9, The polymer is a copolymer comprising a polyvinyl alcohol structure and a first monomer unit, The first monomer unit is at least one of (meth)acrylonitrile monomer units and (meth)acrylic acid monomer units. A polymer having a molecular weight distribution of 2.5 or less and a number-average molecular weight of 10,000 or more.

2. The shear rate of the dispersion at 25°C is 10S. －１ The polymer according to claim 1, wherein the viscosity measured is 1,000 mPa·S or less.

3. The polymer according to claim 1 or claim 2, wherein the polymer comprises 0.1 to 80% by mass of a polyvinyl alcohol structure when the polymer is considered to be 100% by mass.

4. The polymer according to any one of claims 1 to 3, which is a block copolymer comprising polymer block A containing a polyvinyl alcohol structure and polymer block B containing the first monomer unit.

5. A composition comprising a polymer according to any one of claims 1 to 4, a conductive additive, and a dispersion medium.

6. A composition comprising a polymer, a conductive additive, and a dispersion medium, The above composition has a shear rate of 1S at 25°C. －１ and 10S －１ The steady flow viscosity measured by η Ｘ１ η Ｘ１０ The complex viscosity of the composition, measured at 25°C at angular frequencies of 1 rad / s and 10 rad / s, is given by mPa·s. Ｙ１ η Ｙ１０ When expressed as mPa·S, η Ｙ１ / η Ｘ１ η Ｙ１０ / η Ｘ１０ However, it ranges from 0.6 to 1.

9. The polymer is a copolymer comprising a polyvinyl alcohol structure and a first monomer unit, The first monomer unit is at least one of (meth)acrylonitrile monomer units and (meth)acrylic acid monomer units. A composition in which the copolymer has a molecular weight distribution of 2.5 or less and a number average molecular weight of 5,000 or more.

7. The composition according to claim 5 or 6, wherein when the composition is considered to be 100% by mass, the amount of the conductive additive in the composition is 2 to 20% by mass.

8. A slurry for a positive electrode comprising the composition according to any one of claims 5 to 7 and a positive electrode active material.

9. A positive electrode comprising a metal foil and a coating film of the positive electrode slurry according to claim 8 formed on the metal foil.

10. A secondary battery comprising the positive electrode described in claim 9, wherein the secondary battery is one or more selected from the group consisting of a lithium-ion secondary battery, a sodium-ion secondary battery, a magnesium-ion secondary battery, or a potassium-ion secondary battery.

11. The positive electrode active material is LiNi Ｘ Mn （２－Ｘ） O ４ (However, 0 < X ​​< 2), Li(Co Ｘ Ni Ｙ Mn Ｚ ) O ２ (wherein 0 < X ​​< 1, 0 < Y < 1, 0 < Z < 1, and X + Y + Z = 1), and Li(Ni Ｘ Co Ｙ Al Ｚ ) O ２ The secondary battery according to claim 10, wherein it includes at least one selected from 0 < X ​​< 1, 0 < Y < 1, 0 < Z < 1, and X + Y + Z = 1.

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