Method and apparatus for detecting defects of fuel cell membrane-electrode assembly

Patent metadata

Field	Value
Publication number	US-9653743-B2
Application number	US-201414550926-A
Country	US
Kind code	B2
Filing date	Nov 22, 2014
Priority date	Jul 9, 2014
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

Disclosed herein is a method of detecting defects of a fuel cell membrane-electrode assembly which comprises a gas diffusion layer, a catalyst layer and an electrolyte membrane. The method includes steps of: supplying gas to a first side of the membrane-electrode assembly; deducing a pressure of the supplied gas and a permeation rate of the gas permeating to a second side of the membrane-electrode assembly and then deducing an interface pressure between the electrolyte membrane and the gas diffusion layer of the membrane-electrode assembly using the deduced pressure of the supplied gas and the permeation rate; calculating a gas permeability of the electrolyte membrane using the deduced values of the pressure of the supplied gas and the permeation rate and a predetermined outlet pressure at the second side of the membrane-electrode assembly; and determining a defect state of the electrolyte membrane using a variation in the calculated gas permeability according to a change in the pressure of the supplied gas.

First claim

What is claimed is:

1. A method of detecting defects of a fuel cell membrane-electrode assembly which comprises a gas diffusion layer, a catalyst layer and an electrolyte membrane, comprising steps of:
supplying gas to a first side of the membrane-electrode assembly;
deducing a pressure of the supplied gas and a permeation rate of a permeated gas to a second side of the membrane-electrode assembly, and then deducing an interface pressure between the electrolyte membrane and the gas diffusion layer of the membrane-electrode assembly using the deduced pressure of the supplied gas and the permeation rate;
calculating a gas permeability of the electrolyte membrane using the permeation rate, the deduced interface pressure and a predetermined outlet pressure at the second side of the membrane-electrode assembly; and
determining a defect state of the electrolyte membrane using a variation in the calculated gas permeability according to a change in the pressure of the supplied gas.

2. The method of claim 1 , wherein the interface pressure (P m ) is calculated by the following Equation:
P m ={(α Ca.Pt+GDL /β Ca.Pt+GDL ) 2 +2 P h (α Ca.Pt+GDL /β Ca.Pt+GDL )+ P h 2 −2 F /β Ca.Pt+GDL } 1/2 −α Ca.Pt+GDL /β Ca.Pt+GDL

wherein α Ca.Pt+GDL is a Knudsen flow permeation coefficient of the gas diffusion layer, β Ca.Pt+GDL is a viscous flow permeation coefficient of the gas diffusion layer, P h is the pressure of the supplied gas, and F is a gas permeation rate.

3. The method of claim 2 , wherein the interface pressure is the pressure of the supplied gas at an interface between the electrolyte membrane and the catalyst layer.

4. The method of claim 2 , wherein the Knudsen flow permeation coefficient of the gas diffusion layer is calculated by the following Equation:

α
=

[

8
⁢
r

]

[

3
⁢

L
⁡

(

2
⁢
π
⁢

⁢
MRT

)

1
/
2

]

⁢

ɛ

k
t

wherein r is an average pore radius in meter; L is a thickness of the electrolyte membrane in meter; R is a gas constant of about 8.314 J/mol·k; T is a measured temperature in K; M is a molecular weight of the permeated gas in kg/mol; ε is a porosity of the gas diffusion layer; and k t is a flexibility constant of the pores of the gas diffusion layer.

5. The method of claim 2 , wherein the viscous flow permeation coefficient of the gas diffusion layer is calculated by the following Equation:

β
=

[

r
2

]

[

8
⁢
L
⁢

⁢
μ
⁢

⁢
RT

]

⁢

ɛ

k
t

wherein r is an average pore radius in meter; L is a thickness of the electrolyte membrane in meter; R is a gas constant of about 8.314 J/mol·k; T is a measured temperature in K; M is a molecular weight of the permeated gas in kg/mol; ε is a porosity of the gas diffusion layer; and k t is a flexibility constant of the pores of the gas diffusion layer.

6. The method of claim 2 , wherein the Knudsen flow permeation coefficient of the gas diffusion layer and the viscous flow permeation coefficient of the gas diffusion layer are experimentally deduced from an intercept of a straight line when the gas is supplied to the first side of a catalyst layer-gas diffusion layer laminate and then a gas permeability of the catalyst layer-gas diffusion layer laminate is plotted by the Equation q=α+β·P av at an average pressure of pressure of a gas discharged from the catalyst layer-gas diffusion layer laminate and pressure of the supplied gas.

7. The method of claim 6 , wherein a gas permeation rate of the gas permeating the catalyst layer-gas diffusion layer laminate is detected, and the gas permeability of the catalyst layer-gas diffusion layer laminate is calculated by dividing the detected gas permeation rate by a difference between the pressure of the gas supplied to the catalyst layer-gas diffusion layer laminate and the pressure of the gas discharged from the catalyst layer-gas diffusion layer laminate.

8. The method of claim 1 , wherein the gas permeation rate is detected by a detection unit.

9. The method of claim 1 , wherein the gas permeability is calculated by dividing the deduced gas permeation rate by the difference between the interface pressure and the predetermined outlet pressure.

10. The method of claim 1 , wherein the gas permeation rate and the gas permeability are deduced at an average pressure while the gas permeates the membrane-electrode assembly.

11. The method of claim 1 , wherein the electrolyte membrane is determined as a normal state when the gas permeability calculated during the step of supplying the gas is maintained at a predetermined value as the pressure of the supplied gas increases.

12. The method of claim 1 , wherein it is determined that macrocracks greater than microcracks are formed in the electrolyte membrane when the calculated gas permeability increase as the pressure of the supplied gas by plotting against each arithmetic mean pressure between the interface pressure (P m ) and the outlet pressure (P 1 ).

13. The method of claim 1 , wherein it is determined that microcracks are formed in the electrolyte membrane when the pressure of the supplied gas increases and the calculated gas permeability decreases by plotting against each arithmetic mean pressure between the interface pressure (P m ) and the outlet pressure (P 1 ).

Assignees

• Hyundai Motor Co Ltd

Inventors

• Ahn Sang Yeoul
• Lim Tae Won
• Ahn Byung Ki
• Lee Hyun Seung
• Park Yong Sun
• Lee Sung Keun

Classifications

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M8/04783

  Pressure differences, e.g. between anode and cathode · CPC title

• H01M8/04432

  Pressure differences, e.g. between anode and cathode · CPC title

• G01N7/10

  by allowing diffusion of components through a porous wall and measuring a pressure or volume difference · CPC title

• H01M8/04671 Primary

  of the individual fuel cell · CPC title