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-2022367875-A1
Application number	US-202017755107-A
Country	US
Kind code	A1
Filing date	Oct 23, 2020
Priority date	Oct 31, 2019
Publication date	Nov 17, 2022
Grant date	—

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 m2/g or more.

First claim

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.

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 subjecting the feedstock carbon nanotubes that have been subjected to the acid treatment to base treatment; 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

• C08K2201/006

  Additives being defined by their surface area · CPC title

• C08K3/041

  Carbon nanotubes · CPC title

• C08F212/08

  Styrene · CPC title

• C08F236/06

  Butadiene · CPC title

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title