# US 2014/0193737 A1 · Membrane-electrode assembly, fuel cell stack, fuel cell system and operation method thereof

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- Number: US 2014/0193737 A1
- Document ID: US20140193737A1
- Status: Published application
- Kind: A1
- Application number: 14/127,139
- Filed: 2013-02-27
- Published: 2014-07-10
- Earliest claimed: 2012-04-20
- Assignees: Panasonic Corporation
- Applicants: Panasonic Corporation
- Inventors: Hiroshi Ishikawa; Yoichiro Tsuji
- Web page: https://patentgrep.com/patent/US20140193737A1

## CPC

- H01M 8/1004: characterised by membrane-electrode assemblies [MEA] (H01M8/12 takes precedence)
- H01M 4/881: {Electrolytic membranes}
- H01M 8/0234: Carbonaceous material
- H01M 8/0239: Organic resins; Organic polymers
- H01M 8/0243: in the form of mixtures
- H01M 4/8828: {Coating with slurry or ink}
- H01M 4/8882: {Heat treatment, e.g. drying, baking}
- H01M 4/8896: {Pressing, rolling, calendering (membrane electrode assemblies H01M8/1004)}
- H01M 2008/1095: {Fuel cells with polymeric electrolytes}
- Y02E 60/50: Fuel cells
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A membrane-electrode assembly includes: a polymer electrolyte membrane; catalyst layers disposed on the polymer electrolyte membrane; and gas diffusion layers respectively disposed on the catalyst layers. Each of the gas diffusion layers is constituted by a porous member containing electrically-conductive particles and polymer resin as major components, and a ratio (y/x) of a tensile strength y (N/cm) of the gas diffusion layer to a dry-wet size change rate x (%) of the polymer electrolyte membrane is 0.10 or higher.

## Claims

### Claim 1

A membrane-electrode assembly comprising:
a polymer electrolyte membrane;
catalyst layers disposed on the polymer electrolyte membrane; and
gas diffusion layers respectively disposed on the catalyst layers, wherein:
each of the gas diffusion layers is constituted by a porous member containing electrically-conductive particles and polymer resin as major components; and
a ratio y/x of a tensile strength y (N/cm) of the gas diffusion layer to a dry-wet size change rate x (%) of the polymer electrolyte membrane is 0.10 or higher.

### Claim 2 (depends on 1)

The membrane-electrode assembly according to claim 1, wherein the tensile strength y of the gas diffusion layer is 4.2 N/cm or lower.

### Claim 3 (depends on 1)

The membrane-electrode assembly according to claim 1, wherein each of the dry-wet size change rate in a length direction that is a flow direction of the polymer electrolyte membrane when producing the polymer electrolyte membrane and the dry-wet size change rate in a width direction perpendicular to the length direction is 20% or lower.

### Claim 4 (depends on 1)

The membrane-electrode assembly according to claim 1, wherein an adhesive strength between the catalyst layer and the gas diffusion layer is 0.1 MPa or higher.

### Claim 5 (depends on 1)

A fuel cell stack comprising
a plurality of cells, each including the membrane-electrode assembly according to claim 1 and a pair of plate-shaped separators sandwiching the membrane-electrode assembly, wherein
a width of a groove that is a reactant gas channel formed on a main surface of each of the separators is 1.1 mm or shorter, the main surface being opposed to the gas diffusion layer of the membrane-electrode assembly.

### Claim 6 (depends on 1)

A fuel cell system comprising:
a fuel cell stack including a plurality of cells, each including the membrane-electrode assembly according to claim 1 and a pair of plate-shaped separators sandwiching the membrane-electrode assembly, reactant gas channels being respectively formed on main surfaces of the separators, the main surfaces being respectively opposed to the pair of gas diffusion layers of the membrane-electrode assembly; and
a reactant gas supply device configured to respectively supply a fuel gas and an oxidizing gas as reactant gases to the reactant gas channels of the pair of separators.

### Claim 7 (depends on 1)

A method of operating a fuel cell system,
the fuel cell system comprising:
a fuel cell stack including a plurality of cells, each including the membrane-electrode assembly according to claim 1 and a pair of plate-shaped separators sandwiching the membrane-electrode assembly, reactant gas channels being respectively formed on main surfaces of the separators, the main surfaces being respectively opposed to the pair of gas diffusion layers of the membrane-electrode assembly; and
a reactant gas supply device, wherein
the fuel cell stack generates electric power in such a manner that the reactant gas supply device respectively supplies a fuel gas and an oxidizing gas as reactant gases to the reactant gas channels of the pair of separators of the fuel cell stack.

### Claim 8 (depends on 7)

The method according to claim 7, wherein the fuel cell stack generates the electric power under conditions that a temperature inside the fuel cell stack is not lower than 5° C. and not higher than 90° C.

### Claim 9 (depends on 7)

The method according to claim 7, wherein the fuel cell stack generates the electric power under conditions that a relative humidity inside the membrane-electrode assembly is not lower than 0% and not higher than 100%.