RPI Talk Fuel Cells

Novel Designs of Polymer Electrolyte Membrane (PEM) Fuel Cells

Ranga PitchumaniAdvanced Materials and Technologies Laboratory

Department of Mechanical Engineering

Virginia Tech

Blacksburg, VA 24061-0238

http://www.me.vt.edu/amtl

Presented at the Department of Mechanical, Aerospace and Nuclear EngineeringRensselaer Polytechnic Institute, October 29, 2008

Advanced Materials and Technologies Laboratory

MISSION: Conduct research towards improving the fundamental description and

understanding of complex physical phenomena governing materials processing

and design, and emerging technologies. The fundamental description and

understanding are applied towards practical development, design, optimization

and control.

LAB PERSONNEL:

6-8 Graduate Students, 1-2 Postdocs

2 Undergraduate Students

2-3 High School Students each summer

RESEARCH AREAS: Advanced Materials Processing

Microsystems and Micromanufacturing

Fuel Cells/Energy

Design and Manufacturing

Core Sciences

Research Sponsors ($4M)

Industries7%NASA

11%

DOD44%

NSF38%

$4.7M total funding

Polymer Electrolyte Membrane (PEM) Fuel Cells

Fuel cells convert chemical energy directly to electrical energy. With the

byproducts being only water and heat, they are attractive candidates for

clean power generation.

Fuel Cell Performance and Related Issues

Measured in terms of a Cell voltage – Current density variation, referred to

as a polarization curve.

Ce

ll V

olt

ag

e, V

Average Current Density, I

Local current density could be high and its spatial

variation is a factor influencing membrane reliability; it is

desirable to minimize the spatial variation.

A second issue pertains to the system complexity

associated with balance of plant; it is desirable to

reduce system complexity.

Outline

Uniformity of current density in fuel cells

Tailoring of operating parameters

Materials design

Air-breathing fuel cells for reduced complexity

Micro fuel cells

cells E

0 y

y const.; p

0 y

v ; 0

y

u

ia

0x

mm

0 x

s

s

Mem

bra

ne

An

od

e g

as d

iffusio

n

An

od

e c

ata

lyst

const.y

const.y ;0y

const.v ;0u

OH

OH

2

22

const.y

0y const.;y

const.v ;0u

OH

OH

2

22

0s

xy

0 y

y const.; p

0 y

v ; 0

y

u

ic

Cath

od

e g

as d

iffusio

n

Cath

od

e c

han

nel

An

od

e c

han

nel

Cath

od

e c

ata

lyst

Computational Modeling

(r V ) Sc

(r V

r V ) p (

r V ) Su

(r V y i) ( Di

eff y i) Si

( s

eff

s) Ss 0.0

( m

eff

m ) Sm 0.0

0

anode:

cathode:

0

0

Sc

0 0Membrane

anode:

cathode:Catalystlayers

0 0GDL/screen

0 00Gas channels

Ss , Sm Si SuDescription

OHc

Oc M

F

jM

F

j22 24

22 H

a MF

j22

Ha MF

j

24 O

c MF

j

OHc MF

j22

0

0

am

as

jS

jS

0

0

cm

cs

jS

jS

Vk

mffFcz

k

kV

k

mffFcz

k

kV

k

cells E

0 y

y const.; p

0 y

v ; 0

y

u

ia

0x

mm

0 x

s

s

Mem

bra

ne

An

od

e g

as d

iffusio

n

An

od

e c

ata

lyst

const.y

const.y ;0y

const.v ;0u

OH

OH

2

22

const.y

0y const.;y

const.v ;0u

OH

OH

2

22

0s

xy

0 y

y const.; p

0 y

v ; 0

y

u

ic

Cath

od

e g

as d

iffusio

n

Cath

od

e c

han

nel

An

od

e c

han

nel

Cath

od

e c

ata

lyst

Butler-Volmer equations: ja ja,ref (xh2

xh2,ref

) a (ea F

RTa

ea F

RTa

); jc jc,ref (xo2

xo2,ref

) c (ecF

RTc

ecF

RTc

)

Anode: msa c s m EcellCathode:

Local Current Density Variation

Iave = 1.09 A/cm2; ΔI = 1.10 A/cm2

0

1

2

3

4

5

6

7

0.105 0.110 0.115 0.120 0.125

Location across the cell in the membrane, x [cm]

I [A/cm2]

1.700

1.500

1.300

1.100

0.900

0.700E

cell = 0.2 V

Locatio

n a

lon

g the

chan

ne

l, y

[cm

]

(a)

0

1

2

3

4

5

6

7

0.105 0.110 0.115 0.120 0.125

Locatio

n a

lon

g the

chan

ne

l, y

[cm

]Location across the cell in the membrane, x [cm]

I [A/cm2]

0.282

0.278

0.274

0.270

(b)E

cell = 0.8 V

Loca

tion a

long t

he c

hannel, y

[cm

] Iave = 0.28 A/cm2; ΔI = 0.02 A/cm2

Mem

bra

ne

An

od

e g

as d

iffusio

n

An

od

e c

ata

lyst

Cath

od

e g

as d

iffusio

n

Cath

od

e c

han

nel

An

od

e c

han

nel

Cath

od

e c

ata

lyst

xy

Bounds on Operating Parameters

330

340

350

360

370

0.2 0.3 0.4 0.5 0.6 0.7 0.8

Cell Voltage, Ecell

[V]

Cell

Tem

pera

ture

, T

[K

] a = 1.3

2.0

5.0

1.5

8.0

12

18

I/Imax

< 20%

3.0

(c)

A

B

C

A design window can be constructed by identifying the bounds of operating parameter inwhich the current density variation is within a specified constraint. The constraint of 0.2(20 percent) is used as an example to illustrate the methodology.

There is an upper bound on the temperature which keeps the non-uniformity of thecurrent density lower than 20%. Decreasing the temperature can help decrease the non-uniformity of the current density.

The maximum power density occurs around Ecell = 0.5 V and T = 353 K (Point A). Fromthat point, power density decreases with either increasing the temperature or decreasingthe temperature.

The stoichiometry can be another criterion to decide the optimum operating conditions.Increasing anode stoichiometry decreases the non-uniformity of the current density.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Ecell

= 0.20 V

Ecell

= 0.35 V

Ecell

= 0.50 V

Ecell

= 0.65 V

Ecell

= 0.80 V

323 333 343 353 363 373

Curr

en

t D

en

sity V

ari

atio

n,

I/I m

ax

Temperature, T [K]

(a)

Cu

rre

nt D

ensity V

ariatio

n

I/I m

ax

330

340

350

360

370

0.2 0.3 0.4 0.5 0.6 0.7 0.8

Cell Voltage, Ecell

[V]C

ell

Tem

pera

ture

, T

[K

]

0.45

0.40

0.30

0.20

Pd = 0.20

0.30

I/Imax

< 20%

(b)

A

Ce

ll T

em

pe

ratu

re, T

[K

]

Y. Zhang, A. Mawardi, R. Pitchumani, ASME J. Fuel Cell Sci. Tech., 2006

Operational DesignY. Zhang, A. Mawardi, R. Pitchumani, ASME J. Fuel Cell Sci. Tech., 2006

Cell Voltage 0.60 V Cell Voltage 0.70 V

max Pd min a

max Pd min a max Pd min a

Ecell [V] 0.45 0.39 0.60 0.60 0.70 0.70

T [K] 353 353 353 361 369 353

pa [atm] 3 3 3 3 3 3

pc [atm] 3 3 7 3 3 3

RHa 1.0 1.0 1.0 1.0 1.0 1.0

RHc 1.0 1.0 1.0 1.0 1.0 1.0

ma [kg/s] 6.5 x 10-5

6.5 x 10-5

6.5 x 10-5

6.5 x 10-5

6.5 x 10-5

2.0 x 10-5

Op

era

tin

g P

ara

mete

r

mc [kg/s] 5.0 x 10-3

5.0 x 10-3

5.0 x 10-4

5.0 x 10-4

5.0 x 10-4

5.0 x 10-4

Pd [W/cm2] 0.52

0.51 0.47 0.42 0.40 0.34

Ob

jecti

ve

1.6 1.4 2.5 2.0 2.2 2.1

Design Window Fig. 11c Fig. 11d Fig. 11c Fig. 8b Fig. 8a Fig. 11b

Concept:

The reactant species concentrations decrease along the channel due tothe reaction consumption, which leads to non-uniform speciesdistribution and the non-uniform current density distribution.

The purpose of the gas diffusion layers in a fuel cell is to distribute thereactant gases into the catalyst layers and to allow for electronicconduction simultaneously.

The gas diffusion layer with gradually increasing porosity along thechannel will help to distribute the reactant gases into the catalyst layermore evenly, correspondingly achieving a uniform current densitydistribution.

Larger catalyst loading increases the surface area for electrochemicalreactions and more reactant species are involved into the reactions.

Implementing gradually increasing catalyst loading on the membranesurface along the channel can compensate for depletion of reactantspecies and reduce the current density variation.

Variations most effective on the cathode side.

Innovative Material Designs

tGDL tmesh

eff

tGDL

GDL

tmesh

mesh

The graded gas diffusion layer consists two parallel layers along the channel—a regular carbon paper gas diffusion layer and a layer of metal mesh with graded porosity along the channel.

The effective local GDL porosity is calculated as the thickness-weighted harmonic mean of the porosities of the two layers, expressed as:

1

Graded GDL

Gasket

+ =

Graded metal meshCarbon paper

2

3

C-paper

GDL

Graded

metal mesh

tGDL tmesh

GDL mesh

Fabrication of a Graded Porosity GDL

The catalyst loading is decided by the porosity of the screens; largerporosity of the screen or multiple printing leads to more catalystparticles being deposited on the membrane surface and increases thecatalyst loading.

The mixture ink of the carbon particles, catalyst particles, liquidmembrane solution and related solvent was screen printed on Teflonfilms using a Systematic Automation Model 81 Series Screen Printer.

Multiple screen printings are used to obtain the graded catalystloading: the first printing covers the entire area and the followingprintings gradually decrease the printing area to obtain aprogressively increasing catalyst loading along the length.

screen

screen printer

The MEA with graded cathode catalyst loading was fabricated through screen printing.

first printing second printing third printing final graded catalyst loading

dry dry dry

The decals are placed on the two sides of the Nafion 112 membrane from Du Pont. After dryingand hot pressing at 403 K and 70 kg/cm2 for 3 minutes with Nafion 112, the Teflon support filmswere peeled off from the anode and cathode sides of the MEA.

Fabrication of Graded Catalyst MEA

Teflon

Teflon

uniform catalyst loading

graded catalyst loadingmembrane

copper wire

1, 5. Anode and Cathode flow channel plates – glass-fiber epoxy composite

2. Anode current collector – metal mesh (Nickel, Dexmet)

3. GDL (SIGRACETR® GDL 10BB, SGL Technologies) and MEA (NRE-211, DuPont)

4. Cathode segmented current collector – metal mesh (Nickel, Dexmet)

6. Teflon Gasket

1 2 3 4 5

6

Local Current Density Measurement

data

data

Gas flow

resistors

Fuel

cell

PC

R6

R5

R4

R3

R2

R1

Data

acquisition

V1

V2

V3

V4

V5

V6

Test load

i

ilocal

R

Vi

2

3

4

1. Fuel cell test station

2. Test load

3. Data acquisition

4. Fuel cell

1

0.0

0.1

0.2

0.3

0.4

0.5

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

Iave

= 0.5 A Iave

= 0.5 A

Iave

= 1.0 A Iave

= 1.0 A

Iave

= 1.5 A Iave

= 1.5 A

Location in the y direction, y [m]

Lo

ca

l C

urr

en

t, I [A

]

The local current distributions with the constant porosity and catalyst loadinggenerally decrease with location along the channel. The variation of the localcurrent along the entire channel increases in magnitude with increase of averagecurrent.

The local current variation along the entire channel with graded parametersdecreases compared with the distribution with the constant parameters at thesame average current.

The design task is to determine the optimum variations of the porosity and thecatalyst loading.

Constant = 0.53 (solid lines)

Graded = 0.25, 0.53, 0.79

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

Iave

= 0.5 A

Iave

= 1.0 A

Iave

= 1.5 A

Iave

= 2.0 A

Iave

= 0.5 A

Iave

= 1.0 A

Iave

= 1.5 A

Iave

= 2.0 A

Lo

ca

l C

urr

en

t, I [A

]


Constant Lc = 0.3 mg/cm2 (solid lines)

Graded Lc = 0.21, 0.32, 0.43 mg/cm2

Measured Local Current Distributions

Lo

ca

l C

urr

en

t [A

]

Lo

ca

l C

urr

en

t [A

]

Parametrization of the gradations: The porosity and the catalyst loadingdistributions are parameterized using

f f0 a(y

L)b;

f for graded porosity GDL

f Lc for graded catalyst loading

f

f1 (0 y y1)

f2 (y1 y y2)

f3 (y2 y L)

Design of the variations is posed as an optimization problem

Optimum GDL and Catalyst Gradations

power law functional form

piecewise constant form

y = 0 y = L

y1 y2

f1

f2

f3

Optimum

f0, a, b

or

f1, f2, f3

Yes

Fuel Cell Simulation

(Fluent)

Nelder–Mead

Simplex Optimization

(MATLAB)

Initial guess of

parameters

f0, a, b or f1, f2, f3

∆I/Imin and

Pd

Optimality

Conditions

Satisfied?

No

new

f0, a, b

or

f1, f2, f3

Maximizef0 ,a,b or f1 , f2 , f3

Pd

I

Imin

Imax Imin

Imin

%

0 f0 (1 a) 0 < f1 1

a 0 or 0 < f2 1

b 0 0 < f3 1

0.0

0.2

0.4

0.6

0.8

1.0

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

= 0.482

= 0.20+0.797(y/L)1.84Poro

sity o

f C

ath

ode

GD

L,


Ecell

= 0.5 V, I/Imin

= 5%

(a)

9000

9500

10000

10500

11000

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

= 0.482

= 0.20+0.797(y/L)1.84

Lo

ca

l C

urr

ent D

en

sity

, I [A

/m2]


Ecell

= 0.5 V, I/Imin

= 5%

(b)

Optimum Parameters and Current Density Distributions

GD

L P

oro

sity

Lo

ca

l C

urr

en

t D

en

sity [A

/m2]

4500

4700

4900

5100

5300

5500

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

Lc = 0.31

Lc = 0.23+0.16(y/L)1.18

Lo

ca

l C

urr

en

t D

en

sity, I [A

/m2]


Ecell

= 0.50 V, I/Imin

= 5%

(b)

0.0

0.1

0.2

0.3

0.4

0.5

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

Lc = 0.31

Lc = 0.23+0.16(y/L)1.18

Ca

tho

de

Ca

taly

st L

oa

din

g, L

c [m

g/c

m2]


Ecell

= 0.50 V, I/Imin

= 5%

(a)

Lo

ca

l C

urr

en

t D

en

sity,

[A

/m2]

Cata

lyst L

oa

din

g [m

g/c

m2]

9000

10000

11000

12000

13000

14000

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

= 0.175+0.824(y/L)2.92

= 0.184, 0.307, 0.985Lo

ca

l C

urr

ent D

en

sity

, I [A

/m2]


Ecell

= 0.35 V, I/Imin

= 20%(b)

0.0

0.1

0.2

0.3

0.4

0.5

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

Lc = 0.18+0.26(y/L)1.74


Ca

tho

de C

ata

lyst L

oad

ing, L

c [

mg

/cm

2]

(a)

Ecell

= 0.35 V, I/Imin

= 10%

0.190.22

0.37

0.0

0.2

0.4

0.6

0.8

1.0

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

= 0.174+0.829(y/L)3.08

Po

rosity

of C

ath

od

e G

DL,


(a)E

cell = 0.35 V, I/I

min = 20%

0.184

0.307

0.985

6500

7000

7500

8000

8500

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

Lc = 0.18+0.26(y/L)1.74

Lc = 0.19, 0.22, 0.37Lo

ca

l C

urr

en

t D

en

sity, I [A

/m2]


Ecell

= 0.35 V, I/Imin

= 10%(b)

Comparison Between Discrete and Continuous Profiles

GD

L P

oro

sity

Lo

ca

l C

urr

en

t D

en

sity [A

/m2]

Lo

ca

l C

urr

en

t D

en

sity,

[A

/m2]

Cata

lyst L

oa

din

g [m

g/c

m2]

Air-breathing Fuel Cells

If the cathode gas channel is eliminated, and the cathode surface is

directly exposed to the ambient air, the fuel cell draws air by natural

convection

The design eliminates the need for a pumping system and flow channels

at the cathode (partially-passive design)

FC System Cost Breakdown (Carlson, et al., 2005):

– 63% stack (77% bipolar plate); 34% BOP

An air-breathing fuel cell cartridge consists of two fuel cells sharing a

common hydrogen flow chamber at the anode

An array of several cartridges can be used to construct a fuel stack to

meet application requirements

Air Breathing PEMFC Cartridge and Stack

Fuel cell cartridges

Power Converter

Active Natural Convection

Area

2b

H

h

Ls

2 15 4 3

yx

H

1. Frame2. Metal mesh3. GDL4. Catalyst5. Membrane6. H2 chamber

Na

tura

l Co

nv

ectio

n

AirH2

Na

tura

l Co

nv

ectio

n

Air

6

Computational Modeling

solidgas

eff

m

51eff

m

s

eff

s

refi

51eff

i

mm

eff

m

ss

eff

s

T

eff

p

ii

eff

ii

V

c

k1kk

1

DD

Where

00S

00S

STkTVc

SyDyV

SgVpVV

SV

)(

)(

.)(

.)(

)()(

)()(

)()(

)(

.

,

.

Symmetric

(stack)

Heated Bottom

Wall (stack)

ST

ja ai2

meff

(anode)

jc ci2

meff

(cathode)

i2

meff

(membrane)

Validation and Results

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Experiment (ma = 0.1 lpm)

Simulation (ma = 0.1 lpm)

0 1,000 2,000 3,000 4,000 5,000

Cell

Voltage, E

cell [

V]

Current Density, I [A/m 2]

T = 298 K, RHa = 0, H = 1.68 cm

0.0

2.0

4.0

6.0

8.0

10.0

Simulation

Experiment

0 1,000 2,000 3,000 4,000

Current Density, I [A/m2]

Sta

ck V

oltage, E

sta

ck [V

]

H = 5.0 cm, Number of Cartridges: 5

0.0

0.2

0.4

0.6

0.8

1.0

h = 0.0 mm

h = 0.5 mm

h = 2.0 mm

h = 10.0 mm

0 2,000 4,000 6,000 8,000


Cell

Voltage, E

ce

ll [V

]

H = 5.0 cm

0.0

0.2

0.4

0.6

0.8

1.0

b = 2.0 mm

b = 4.0 mm

b = 6.0 mm

0 2,000 4,000 6,000 8,000


Cell

Voltage, E

ce

ll [V

]

H = 5.0 cm


Power Converter


Area

2b

H

h

Ls

Y. Zhang, A. Mawardi, R. Pitchumani, J. Power Sources, 2007

Y. Zhang and R. Pitchumani, Int. J. Heat and Mass Transfer, 2007

Stack Design Example

From the polarization curves for various cartridge spacing, the relation between current densityand power density and cartridge spacing can be derived.

The peak current density and power density decreases as cell voltage density increases

A design case where the fuel cell is specified to operate at Estack = 8 V, Pstack = 40 W, and themaximum stack length, Ls= 8 cm, is considered. The cartridge thickness is t = 6.5 mm.

The required cell voltage density is E’ = Estack/Ls = 0.1 V/mm, which has a peak power density of1700 W/m2 at an inter-cartridge spacing of 2b = 3.5 mm (Point A).

The number of cartridges required is: N = Ls/(2b+t) = 8. The cell voltage Ecell = Estack/2N = 0.5 V.

Since, for the value of E’ = 0.1 V/mm and 2b = 3.5 mm, the current density is I = 3450 A/m2, andthe current required is I stack= Pstack / Estack= 5 A, the active area of each side of the cartridge is A= Istack / I= 14.5 cm2. The cartridge width is W = A/H=2.9 cm.

Y. Zhang, A. Mawardi, R. Pitchumani,

J. Power Sources, 2007

0

500

1,000

1,500

2,000

2,500

3,000

E' = 0.050 V/mm

E' = 0.075 V/mm

E' = 0.100 V/mm

E' = 0.150 V/mm

0 2 4 6 8 10 12

Cartridge Spacing, 2b [mm]

H = 5.0 cm

Po

we

r D

en

sity, P

d [W

/m2]

A

(b)

Pow

er

Density [

W/m

2]

0

3,000

6,000

9,000

E' = 0.050 V/mm

E' = 0.075 V/mm

E' = 0.100 V/mm

E' = 0.150 V/mm

0 2 4 6 8 10 12

Cartridge Spacing, 2b [mm]

H = 5.0 cm

Ave

rag

e C

urr

en

t D

en

sity, I a

ve [A

/m2]

(a)

A

Ave C

urr

ent D

ensity [

A/m

2]

0.0

0.2

0.4

0.6

0.8

1.0

b = 2.0 mm

b = 4.0 mm

b = 6.0 mm

0 2,000 4,000 6,000 8,000


Cell

Voltage, E

ce

ll [V

]

H = 5.0 cm


Power Converter


Area

2b

H

h

Ls

Hybrid Fuel Cell/Battery System

Design specifications:

25 W avg. power, 40 W peak power (9:1 nominal/peak power duration ratio)

Power delivery at 12 VDC (regulated)

Hydrogen fuel, and air-cooled

Provide at least 1800 Wh of energy over 72 hrs

Fuel Cell

DC/DC

Converter12 VDC

01

16

Fu

el C

ell

Sta

ck

Wide Input Range

DC-DC Converter

Up to 16 Channels

12V Output

Computer

RS-232 Serial

Communication

Power Management

MicrocontrollerADC

Memory

(EEPROM)

Real-time Clock

Multiplexer

Backup Battery

CSR

CSR

CSR

CSR: Current Sensing Resistor

ADC: Analog to Digital Converter

Monitor/

ControlControl

On-board

Temperature

Sensor

MultiplexerVoltage/Current

LCD

Prototype System

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15.0

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35

0 1 2 3 4

Voltage (V)

Power (W)

Current, I [A]

Sta

ck V

olta

ge

, E

Sta

ck [

V]

Po

we

r, P [W

]

T = 25 oC, RHa = 0 %, H

2 Pressure=5 psi

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Voltage (V)

Power (W)

Po

wer

(W)

Vo

ltag

e (

V)

Time (Hrs)

Long Term TestFive units (10 fuel cells), room temperature, flow rate = 0.75lpm

Planar PEM Micro Fuel Cell (µPEMFC)

Traditional fuel cell designs are based on a ―sandwich‖ construction of

stacking constituent layers

Micro and miniature fuel cell designs have also focused primarily on the

layered design, while shrinking the size

Proposed concept is that of combining microfabrication techniques with

fuel cell technologies to achieve compact, modular, and scalable designs

for high power density

A unique feature of the PEMFC design is that the cathode and the

anode channels are patterned in a planer configuration. The design also

eliminates gas diffusion layers

Design lends itself to fabrication of fuel cell arrays with associated

circuitry on a single wafer

Planar PEM Micro Fuel Cell (µPEMFC)

H+

Patterned Nafion® micro channels

No gas diffusion layers

H2 and air operation

Concept also applicable to direct methanol fuel cells (DMFC)

H2

O2

Membrane

x

y

(a) y

zCatalystCatalyst

H2 O2

(b)

View A-A’

PDMS

A

A’

500 m Si Substrate

40~50 m Nafion®

Fabrication

Si Substrate

Nafion®

Si Micro Die

1. Solution casting

2. Hot pressing of microchannels

3. Current collector depositionAu Au

mask

Substrate

Substrate

Nafion

Pt/C Catalyst

mask

4. Catalyst deposition

Substrate

PDMS

H+H2 O2

5. Sealing with PDMS Active area ~0.33 mm2

Channel width = 500 um

Channel length = 25 mm

PEMFC Testing

0

0.1

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0.4

0.5

0.6

0.7

0.8

0.9

0.00 42.67 85.33 128.00 218.66 253.33

I (mA/cm2)

V (

V)

0

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P (

mW

/cm

2)

V (V)

P (mW/cm2)

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140

Po

we

r D

en

sit

y (

mW

/cm

2)

Min

ne

so

ta

Fra

un

ho

fer

UC

ON

N

Be

ll La

bs

Sta

nfo

rd

Illino

is

Ca

se

We

ste

rn

Lo

uis

ian

a T

ech

Research Group

Comparison of Power Densities Obtained by Various Research Groups

PEMFC Arrays and Interdigitated Stacks

Parallel stack of 7 PEMFCs

Series-parallel stack of 21 PEMFCs

Summary

Strategies for achieving uniformity of current density in a PEM fuel cell were discussed. One approach is based on tailoring the operating parameters while the other approach is that of using graded gas diffusion and/or catalyst layers.

A semi-passive air-breathing fuel cell design was presented. A prototype stack was developed to meet target requirements.

A novel planar micro fuel cell design was discussed, which presents opportunities for high density micro power generation and integration with microelectronics.

Acknowledgments

The work was funded by the U.S. Army RDE-COM through Contract No. DAAB07-03-3-K-415.

Students, postdocs and collaborators

Dr. Andryas Mawardi (Chrysler Corporation)

Dr. Yanyan Zhang (GM Fuel Cells)

Dr. Richard Johnson (ASML)

Brian Elolampi (Analog Devices)

Simon Wong (Cornell)

Runhong Deng (Symbol Technologies)

Profs. Lei Zhu (CMBE) and Robert Magnusson (ECE)

Documents

RPI Talk Fuel Cells