Air electrode, metal-air battery, and method for producing air electrode

Patent metadata

Field	Value
Publication number	US-10971775-B2
Application number	US-201816490272-A
Country	US
Kind code	B2
Filing date	Mar 13, 2018
Priority date	Mar 16, 2017
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

A method for producing an air electrode includes a kneading step of kneading an oxygen reduction catalyst, a conductive auxiliary agent, and a water-repellent resin (binder) in a water solvent; and a rolling step of rolling with a roller the kneaded product produced in the kneading step. The rolling step includes rolling the kneaded product with the roller several times in many directions (at least two or more different rolling directions). In the formed air electrode, the water-repellent resin is fiberized in the air electrode, and the fibers thereof are oriented in many directions to form a netlike shape.

First claim

The invention claimed is:

1. An air electrode comprising
a sheet catalyst layer,
a fiberized water-repellent resin contained in the sheet catalyst layer and oriented in at least two and more directions in the planar direction of the sheet catalyst layer,
an oxygen reduction catalyst bound with the fiberized water-repellent resin, and
a conductive auxiliary agent bound with the fiberized water-repellent resin.

2. The air electrode according to claim 1 , wherein the oxygen reduction catalyst is the α-type manganese oxide and,
the α- type manganese dioxide has a particle diameter of 50 nm to 15 μm.

3. The air electrode according to claim 1 , wherein
the oxygen reduction catalyst is an α-type manganese oxide and,
the α-type manganese dioxide has an average particle diameter of 100 nm to 2 μm.

4. The air electrode according to claim 1 , wherein
the oxygen reduction catalyst is an α-type manganese oxide and,
the α-type manganese dioxide has a specific surface area of 150 m 2 /g to 300 m 2 /g.

5. The air electrode according to claim 1 , wherein the conductive auxiliary agent is carbon black and,
the carbon black has an average particle diameter of 20 to 40 nm.

6. The air electrode according to claim 1 , wherein the fiberized water-repellent resin is polytetrafluoroethylene.

7. The air electrode according to claim 1 , wherein the fiberized water-repellent resin has an average fiber diameter of 100 to 200 nm.

8. The air electrode according to claim 1 , wherein the weight ratio of the conductive auxiliary agent to the oxygen reduction catalyst is 1.2 to 1.7.

9. The air electrode according to claim 1 , wherein the fiberized water-repellent resin is 15 to 25% of the total weight of the air electrode.

10. The air electrode according to claim 1 ,
wherein the fiberized water-repellent resin is polytetrafluoroethylene; and
the ratio of the average fiber diameter of fiberized water-repellent resin composed of the polytetrafluoroethylene to the average particle diameter of the oxygen reduction catalyst is 1/10 to 1/5.

11. The air electrode according to claim 1 , wherein the value obtained by dividing the weight ratio of the fiberized water-repellent resin in the air electrode by the average fiber diameter of the fiberized water-repellent resin is 75 to 250.

12. A method for producing an air electrode comprising:
a kneading step of kneading an oxygen reduction catalyst, a conductive auxiliary agent, and a water-repellent resin in a water solvent; and
a rolling step of rolling with a roller the kneaded product prepared in the kneading step,
wherein the rolling step includes rolling the kneaded product with the roller twice or more times and in different directions.

13. The method for producing an air electrode according to claim 12 , wherein in two different rolling directions, the angle formed by the rolling directions is 10° or more and 170° or less.

14. The method for producing an air electrode according to claim 12 , comprising, before the kneading step, a mixing step of mixing the oxygen reduction catalyst and the conductive auxiliary agent,
wherein the kneading step includes kneading the mixture, obtained in the kneading step and containing the oxygen reduction catalyst and the conductive auxiliary agent, and the water-repellent resin with a water solvent.

15. The method for producing an air electrode according to claim 12 , further comprising, before the kneading step, a grinding step of grinding the oxygen reduction catalyst.

16. The method for producing an air electrode according to claim 12 , wherein
a thickness of the kneaded product is gradually decreased in the rolling step.

17. A metal-air battery comprising
a metal negative electrode,
an air electrode arranged opposed to the metal negative electrode and comprising a sheet catalyst layer, a fiberized water-repellent resin contained in the sheet catalyst layer and oriented in at least two directions in the planar direction of the sheet catalyst layer,
an oxygen reduction catalyst bound with the fiberized water-repellent resin, and
a conductive auxiliary agent bound with the fiberized water-repellent resin.

18. The metal-air battery according to claim 17 , further comprising an electrolyte disposed between the metal negative electrode and the air electrode, wherein
the electrolyte is alkaline aqueous solution.

19. The metal-air battery according to claim 17 , wherein the air electrode comprises an air electrode current collector between the metal negative electrode and the sheet catalyst layer.

20. The metal-air battery according to claim 17 , wherein a thickness of the sheet catalyst layer is thicker than a thickness of the air electrode current collector.

Assignees

• Sharp Kk

Inventors

• Kitagawa Tomo
• Mizuhata Hirotaka
• Mitamura Keigo
• Takenaka Shinobu
• Sata Shunsuke

Classifications

• H01M12/06

  with one metallic and one gaseous electrode · CPC title

• H01M4/8668 Primary

  Binders · CPC title

• H01M2004/8689

  Positive electrodes · CPC title

• H01M4/8673

  Electrically conductive fillers · CPC title

• H01M4/9016

  Oxides, hydroxides or oxygenated metallic salts · CPC title