Thickener powder for lithium-ion battery, water-based electrode slurry, electrode for lithium-ion battery, lithium-ion battery, method for manufacturing water-based electrode slurry for lithium-ion battery, and method for manufacturing electrode for lithium-ion battery

1. A thickener powder for thickening a water-based electrode slurry for a lithium-ion battery, the thickener powder comprising:

a cellulose-based water-soluble polymer,

wherein a content of a water-insoluble component in the thickener powder, which is calculated from the following Condition 1, is equal to or more than 0.01% by mass and equal to or less than 0.5% by mass, and

the water-insoluble component includes a fiber component derived from the cellulose-based water-soluble polymer;

Condition 1: the thickener powder is dissolved in water, thereby obtaining a thickener aqueous solution having a concentration of 1.3% by mass, then, the thickener aqueous solution is filtered using a filter having an average pore diameter of 1 μm, then, the water-insoluble component remaining over the filter is dried, and a mass of the water-insoluble component is measured, and then the content of the water-insoluble component in the thickener powder is calculated.

2. The thickener powder for a lithium-ion battery according to claim 1 ,

wherein the cellulose-based water-soluble polymer includes at least one selected from the group consisting of carboxymethyl cellulose and a carboxymethyl cellulose salt.

3. The thickener powder for a lithium-ion battery according to claim 1 ,

wherein a viscosity calculated from the following Condition 2 is equal to or more than 10 mPa·s and equal to or less than 20,000 mPa·s;

Condition 2: the thickener powder is dissolved in water, thereby obtaining a thickener aqueous solution having a concentration of 1.3% by mass, and then the viscosity of the thickener aqueous solution is measured using a B-type viscometer under conditions of 25° C. and a shear rate of 3.4 s −1.

4. The thickener powder for a lithium-ion battery according to claim 1 ,

wherein the thickener powder is obtained by dissolving the cellulose-based water-soluble polymer in the water-based medium to obtain a cellulose-based water-soluble aqueous solution, thereafter filtering the cellulose-based water-soluble aqueous solution using a filter having an average pore diameter of 1 μm, thereafter drying the filtered cellulose-based water-soluble aqueous solution to remove the fiber component derived from the cellulose-based water-soluble polymer.

5. A water-based electrode slurry comprising:

an electrode active material being selected from a positive electrode active material and a negative electrode active material;

a water-based binder;

the thickener powder for a lithium-ion battery according to claim 1 ; and

a water-based medium,

wherein the thickener powder for a lithium-ion battery is dissolved in the water-based medium.

6. An electrode for a lithium-ion battery, comprising:

an electrode active material being selected from a positive electrode active material and a negative electrode active material;

a water-based binder; and

the thickener powder for a lithium-ion battery according to claim 1 .

7. A lithium-ion battery comprising at least:

a positive electrode;

an electrolyte; and

a negative electrode,

wherein at least one of the positive electrode and the negative electrode includes the electrode for a lithium-ion battery according to claim 6 .

8. A method for manufacturing a water-based electrode slurry for a lithium-ion battery, including an electrode active material being selected from a positive electrode active material and a negative electrode active material, a water-based binder, a thickener, and a water-based medium, the method comprising:

a step of preparing a water-based electrode slurry by mixing the electrode active material, the water-based binder, a thickener powder, and the water-based medium,

wherein the thickener powder is obtained by dissolving the cellulose-based water-soluble polymer in the water-based medium to obtain a cellulose-based water-soluble aqueous solution, thereafter filtering the cellulose-based water-soluble aqueous solution using a filter having an average pore diameter of 1 μm, thereafter drying the filtered cellulose-based water-soluble aqueous solution to remove the fiber component derived from the cellulose-based water-soluble polymer.

9. The method for manufacturing a water-based electrode slurry for a lithium-ion battery according to claim 8 ,

wherein the step of preparing the water-based electrode slurry includes

a step of preparing a mixture including the electrode active material and the thickener powder by dry-mixing the electrode active material and the thickener powder in a powder state,

a step of preparing a slurry precursor by adding one or more liquid components selected from the water-based medium and an emulsion aqueous solution including the water-based binder to the mixture and wet-mixing the components in the mixture, and

a step of preparing the water-based electrode slurry by further adding one or more liquid components selected from the water-based medium and the emulsion aqueous solution including the water-based binder to the slurry precursor and wet-mixing the components in the slurry.

10. A method for manufacturing an electrode for a lithium-ion battery, comprising:

a step of preparing a water-based electrode slurry using the method for manufacturing a water-based electrode slurry for a lithium-ion battery according to claim 8 ; and

a step of forming an electrode active material layer over a base material by applying the obtained water-based electrode slurry over the base material, drying the applied water-based electrode slurry, and removing the water-based medium.