Fuel cell, manufacturing method thereof, electronic apparatus, enzyme-immobilized electrode, manufacturing method thereof, water-repellent agent, and enzyme immobilizing material

Patent metadata

Field	Value
Publication number	US-9912000-B2
Application number	US-74457908-A
Country	US
Kind code	B2
Filing date	Dec 4, 2008
Priority date	Dec 7, 2007
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

In the case in which a fuel cell has a structure in which a cathode ( 2 ) and an anode ( 1 ) are opposed with the intermediary of an electrolyte layer ( 3 ) and the cathode ( 2 ) is formed of an electrode to which an oxygen reductase and so on is immobilized and this electrode has pores inside, at least part of the surface of this electrode is rendered water repellent. For example, the surface of the electrode is rendered water repellent by forming a water-repellent agent on the surface of this electrode. Thereby, in the case in which the cathode is formed of an electrode to which an enzyme is immobilized and this electrode has pores inside, a fuel cell that can stably achieve a high current value by optimization of the amount of water contained in the cathode and a manufacturing method thereof are provided.

First claim

The invention claimed is:

1. A fuel cell comprising:
a structure including a cathode, an anode, and a proton conductor that includes an electrolyte layer and that is formed between the cathode and the anode,
wherein the cathode is a porous carbon-based material having an electron mediator and an enzyme immobilized in direct contact thereon,
wherein after the electron mediator and the enzyme have been immobilized directly on the cathode, a water-repellant material including microparticles is formed on the cathode by immersing the cathode in a water-repellant agent including 13-18% of a carbon powder that is natural graphite, 3-8% of polyvinyl butyral as a binder, and an organic solvent having a solubility of the enzyme of less than 1 mg/ml such that the electron mediator and the enzyme are positioned between the porous carbon-based material of the cathode and the outer water-repellant material,
wherein a particle size of the carbon powder is sufficiently smaller than a pore size of the cathode such that an inside of the pores can be coated with the water-repellant material, and
wherein the electrolyte layer has a charge of a same sign as that of a charge of an oxidized from or a reduced form of the electron mediator.

2. The fuel cell according to claim 1 , wherein a fuel solution is in contact with part of the cathode.

3. The fuel cell according to claim 2 , wherein the fuel solution is in contact with an outer circumferential surface of the anode and a side surface of the cathode.

4. The fuel cell according to claim 3 , wherein a sheet composed of a material through which air passes and the fuel solution does not pass is provided on a surface of the cathode on an opposite side to the proton conductor.

5. The fuel cell according to claim 4 , wherein the proton conductor is formed of a nonwoven fabric.

6. The fuel cell according to claim 1 , wherein the enzyme includes an oxygen reductase.

7. The fuel cell according to claim 6 , wherein the oxygen reductase is bilirubin oxidase.

8. The fuel cell according to claim 6 , wherein an enzyme is immobilized to the anode and the enzyme immobilized to the anode includes an oxidase and promotes oxidation of a monosaccharide to break down the monosaccharide.

9. The fuel cell according to claim 8 , wherein the enzyme immobilized to the anode includes a coenzyme oxidase that returns a coenzyme reduced in linkage with oxidation of the monosaccharide to an oxidized form and passes an electron to the anode via the electron mediator.

10. The fuel cell according to claim 1 , wherein the porous carbon-based material of the cathode is selected from the group consisting of a carbon pellet, carbon felt and carbon paper.

11. The fuel cell according to claim 1 , wherein the enzyme is an oxygen reductase selected from the group consisting of bilirubin oxidase, laccase, ascorbic acid and oxidase.

12. An electronic apparatus comprising one or a plurality of fuel cells, at least one of the fuel cells having a structure including a cathode, an anode, and a proton conductor that includes an electrolyte layer and that is formed between the cathode and the anode,
wherein the cathode is a porous carbon-based material, wherein an electron mediator is immobilized to the cathode in addition to the enzyme having an electron mediator and an enzyme immobilized in direct contact thereon,
wherein after the electron mediator and the enzyme have been immobilized directly on the cathode, a water-repellant material including microparticles is formed on the cathode by immersing the cathode in a water-repellant agent including 13-18% of a carbon powder that is natural graphite, 3-8% of polyvinyl butyral as a binder, and an methyl isobutyl ketone as solvent having a solubility of the enzyme of less than 1 mg/ml such that the electron mediator and the enzyme are positioned between the porous carbon-based material of the cathode and the outer water-repellant material,
wherein a particle size of the carbon powder is sufficiently smaller than a pore size of the cathode such that an inside of the pores can be coated with the water-repellant material, and
wherein the electrolyte layer has a charge of a same sign as that of a charge of an oxidized form or a reduced form of the electron mediator.

13. The electronic apparatus according to claim 12 , wherein the porous carbon-based material of the cathode is selected from the group consisting of a carbon pellet, carbon felt and carbon paper.

14. The electronic apparatus according to claim 12 , wherein the enzyme is an oxygen reductase selected from the group consisting of bilirubin oxidase, laccase, ascorbic acid and oxidase.

Assignees

• Nakagawa Takaaki
• Kumita Hideyuki
• Kakuta Masaya
• Sakai Hideki
• Mita Hiroki
• Goto Yoshio
• Sony Corp

Inventors

• Nakagawa Takaaki
• Kumita Hideyuki
• Kakuta Masaya
• Sakai Hideki
• Mita Hiroki
• Goto Yoshio

Classifications

• Y02E60/50

  Fuel cells · CPC title

• Y02E60/527

  Cross-Sectional Technologies · mapped topic

• H01M4/8605

  Porous electrodes · CPC title

• H01M8/04119

  with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying · CPC title

• Y02P70/56

  Cross-Sectional Technologies · mapped topic