Paste for secondary battery, slurry for secondary battery positive electrode, positive electrode for secondary battery, secondary battery, and method of producing paste for secondary battery

Patent metadata

Field	Value
Publication number	US-12469852-B2
Application number	US-202017755107-A
Country	US
Kind code	B2
Filing date	Oct 23, 2020
Priority date	Oct 31, 2019
Publication date	Nov 11, 2025
Grant date	Nov 11, 2025

Abstract

Provided is a paste for a secondary battery that can cause an electrode mixed material layer to display excellent adhesiveness and can reduce internal resistance of a secondary battery. The paste for a secondary battery contains a conductive additive, a polymer, and a dispersion medium. The conductive additive includes one or more carbon nanotubes having a surface acid content of not less than 0.01 mmol/g and not more than 0.15 mmol/g, a surface base content of not less than 0.005 mmol/g and not more than 0.500 mmol/g, a ratio of the surface acid content relative to the surface base content of not less than 1.3 and not more than 3.0, and a specific surface area of 150 m 2 /g or more.

First claim

The invention claimed is:

1 . A paste for a secondary battery comprising a conductive additive, a polymer, and a dispersion medium, wherein
the conductive additive includes one or more carbon nanotubes having a surface acid content of not less than 0.01 mmol/g and not more than 0.15 mmol/g, a surface base content of not less than 0.005 mmol/g and not more than 0.500 mmol/g, a ratio of the surface acid content relative to the surface base content of not less than 1.3 and not more than 3.0, and a specific surface area of 150 m 2 /g or more, and wherein the surfaces of the one or more carbon nanotubes are substantially free of amino functional groups.

2 . The paste for a secondary battery according to claim 1 , wherein the polymer includes a nitrile group-containing monomer unit in a proportion of not less than 10 mass % and not more than 40 mass % and includes a conjugated diene monomer unit in a proportion of not less than 15 mass % and not more than 55 mass %.

3 . The paste for a secondary battery according to claim 1 , wherein the polymer includes a hydrophilic group.

4 . The paste for a secondary battery according to claim 1 , wherein the polymer has an iodine value of not less than 3 mg/100 mg and not more than 50 mg/100 mg.

5 . The paste for a secondary battery according to claim 1 , wherein proportional content of the conductive additive is not less than 2 mass % and not more than 20 mass %, and proportional content of the polymer is not less than 0.1 mass % and not more than 6 mass %.

6 . A slurry for a secondary battery positive electrode comprising: a positive electrode active material; and the paste for a secondary battery according to claim 1 .

7 . The slurry for a secondary battery positive electrode according to claim 6 , wherein nickel constitutes a proportion of not less than 60.0 mol % and not more than 100.0 mol % among transition metal in the positive electrode active material.

8 . A positive electrode for a secondary battery comprising a positive electrode mixed material layer formed using the slurry for a secondary battery positive electrode according to claim 6 .

9 . A secondary battery comprising the positive electrode for a secondary battery according to claim 8 .

10 . A method of producing the paste for a secondary battery according to claim 1 , comprising:
a step of subjecting one or more feedstock carbon nanotubes to acid treatment; a step of contacting the acid-treated carbon nanotubes with a base treatment wherein a base is selected from the group consisting of lithium hydroxide, sodium bicarbonate, and sodium hydroxide; a step of washing the feedstock carbon nanotubes that have been subjected to the base treatment so as to obtain the carbon nanotubes; and a step of mixing the conductive additive that includes the carbon nanotubes with the polymer and the dispersion medium.

Assignees

• Zeon Corp

Inventors

• Motoki Junpei
• Fukumine Mayumi

Classifications

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/622

  being polymers · CPC title