Intact method of evaluating unit cells in a fuel cell stack and a device using the same

Patent metadata

Field	Value
Publication number	US-9496573-B2
Application number	US-201213353443-A
Country	US
Kind code	B2
Filing date	Jan 19, 2012
Priority date	Sep 5, 2011
Publication date	Nov 15, 2016
Grant date	Nov 15, 2016

Abstract

Disclosed are a method and an apparatus for an intact evaluation of the unit cells in a fuel cell stack. Since the degradation of the unit cells can be detected intactly, i.e. without disassembly of the stack, the time required for the detection and analysis thereof can be greatly reduced.

First claim

What is claimed is:

1. An evaluation apparatus for an intact fuel cell stack, the apparatus comprising:
a galvanostat configured to apply a constant current (I c ) across end plates of the fuel cell stack;
a voltmeter configured to measure voltage across a unit cell of the intact fuel cell stack and time data when the constant current (I c ) is applied across end plates of the intact fuel cell stack;
an oxidant supplier for supplying oxidant to a cathode of the intact fuel cell stack; and
a physical property determining device configured to input data from the galvanostat and the voltmeter and configured to determine:
a capacity of electrical double layer (C dl ) across the unit cell,
a hydrogen adsorption/desorption charge (Q H ) at the unit cell,
a roughness factor (RF) of the unit cell, and
an electrochemical active surface area (EAS) of the unit cell,
wherein C dl is determined in accordance to

I
c

=

C
dl

⁢

Δ
⁢

⁢

V
2

Δ
⁢

⁢

t
2

+

I
etc

,

in which
ΔV 2 is a second voltage change determined along a resultant voltage/time curve generated from the measured voltage and time data when I c is applied across the unit cell,
Δt 2 is a second time zone corresponding to a duration of the ΔV 2 along the resultant voltage/time curve, and
I etc is a current associated with factors other than Q H and C dl , wherein I etc is extrapolated from a y-intercept and C dl is obtained as a slope from a graph of

Δ
⁢

⁢

V
2

Δ
⁢

⁢

t
2

 versus I c when

Δ
⁢

⁢

V
2

Δ
⁢

⁢

t
2

 is plotted along an x-axis and I c is plotted along a y-axis, wherein the Q H is determined in accordance to
Q H =( I c −I etc )Δ t 1 −C dl ΔV 1 ,

in which
ΔV 1 is a first voltage change determined along the resultant voltage/time curve, and
Δt 1 is a first time zone corresponding to a duration of the ΔV 1 along the resultant voltage/time curve,

wherein RF is determined in accordance to

RF
=

Q
H

B
×

A
geo

,

in which
B is a ratio of A real to Q H ,
A geo is an active surface area of the catalyst of the unit cell, and
A real is a total surface area of the catalysts of the unit cell,

wherein EAS is determined in accordance to

EAS
=

Q
H

B
×

W
Pt

,

in which W Pt is a mass of the catalyst of the unit cell,
wherein when calculated values of any one of C dl , I etc , and EAS are determined to be below corresponding predetermined values then the intact fuel cell stack is evaluated as degraded.

2. The evaluation apparatus of claim 1 , wherein the physical property determining device is also configured to determine RF in accordance to

RF
=

A
real

A
geo

.

3. The evaluation apparatus of claim 1 , wherein the intact fuel cell stack comprises a plurality of unit cells.

4. The evaluation apparatus of claim 1 , wherein the catalyst of the unit cell comprises a platinum catalyst.

5. The evaluation apparatus of claim 1 , wherein A real and W Pt are predetermined parameters of the unit cell.

6. The evaluation apparatus of claim 1 , wherein when the catalysts comprises a polycrystalline catalyst then B is 0.21 cm 2 /mC.

7. The evaluation apparatus of claim 1 , wherein Δt 1 corresponds to when hydrogen adsorption/desorption occurs and when the electric double layer charges.

8. An evaluation apparatus for an intact fuel cell stack, the apparatus comprising:
a galvanostat configured to apply a constant current (I c ) across end plates of the fuel cell stack;
a voltmeter configured to measure voltage across a unit cell of the intact fuel cell stack and time data when the constant current (I c ) is applied across end plates of the intact fuel cell stack;
an oxidant supplier for supplying oxidant to a cathode of the intact fuel cell stack; and
a physical property determining device configured to input data from the galvanostat and the voltmeter and configured to determine:
a capacity of electrical double layer (C dl ) across the unit cell, and wherein

C dl is determined in accordance to

I
c

Assignees

• Jang Jong Hyun
• Lee Kug-Seung
• Kim Hyoung-Juhn
• Cho Eun Ae
• Kim Soo-Kil
• Henkensmeier Dirk
• Nam Suk-Woo
• Lim Tae Hoon
• Korea Inst Sci & Tech

Inventors

• Jang Jong Hyun
• Lee Kug-Seung
• Kim Hyoung-Juhn
• Cho Eun Ae
• Kim Soo-Kil
• Henkensmeier Dirk
• Nam Suk-Woo
• Lim Tae Hoon

Classifications

• H01M8/04552

  of the individual fuel cell · CPC title

• Y02E60/50

  Fuel cells · CPC title

• H01M8/0491 Primary

  of fuel cell stacks · CPC title

• H01M4/86

  Inert electrodes with catalytic activity, e.g. for fuel cells · CPC title

• H01M8/04 Primary

  Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids · CPC title