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Development of high temperature PEM fuel cells. Simplification and CO tolerancemapping

Jensen, Jens Oluf; Fernandez, Santiago Martin; Vassiliev, Anton; Cleemann, Lars Nilausen; Li, Qingfeng

Publication date:2015

Document VersionPublisher's PDF, also known as Version of record

Link back to DTU Orbit

Citation (APA):Jensen, J. O. (Author), Fernandez, S. M. (Author), Vassiliev, A. (Author), Cleemann, L. N. (Author), & Li, Q.(Author). (2015). Development of high temperature PEM fuel cells. Simplification and CO tolerance mapping.Sound/Visual production (digital)

https://orbit.dtu.dk/en/publications/0cf7d63d-185f-40d5-906c-0a6ab707f820

DTU Energy Technical University of Denmark

Development of

high temperature PEM fuel cells.

Simplification and CO tolerance mapping Jens Oluf Jensen, Santiago Martin, Anton Vassiliev, Lars N. Cleemann and Qingfeng Li Proton Conductors Department of Energy Conversion and Storage Kemitorvet 207 Technical University of Denmark DK-2800 Lyngby Denmark [email protected]

J.O. Jensen – at "Neptune’s Hydrogen and Fuel Cells", Naples, Dec. 15, 2015



Outline

• The choice of fuel

• CO effect on the PEM fuel cell

• Binderless electrodes

• Lowering the platinum loading



Fueling of fuel cells

Type I Hydrogen

Type II Methanol Dimethyl ether

Type III Natural gas Gasoline/diesel LPG Ethanol

LT PEMFC

Simple reformer

Complex reformer

Purification

HT-PEMFC

Fuel Reforming Purification Fuel cell



Fueling of fuel cells

Type I Hydrogen

Type II Methanol

Dimethyl ether

Type III Natural gas

Gasoline/diesel LPG

Ethanol

Hydrogen Methanol HC

Fuel efficency Systme simplicity Availability Ease of storage



FC temperatures

RT 200ºC 600ºC 1000ºC

MCFC (O2- as CO32-)

SOFC (O2-)

PEMFC (H+)

AFC (H+ via OH-)

PAFC (H+)

100ºC

High temperature fuel cells

Intermediate temperature

fuel cells ?

Low temperature fuel cells



Results with PBI membranes

N

N

N

Nn

HH

Poly (2,2´-m-(phenylene)-5,5´-bibenzimidazole)

Well-known temperature resistant polymer Tg = ~430ºC

When doped with phosphoric acid:

Proton conductor

Wainright and Savinell. J. Electrochem. Soc. 142 (1995) L121

Polybenzimidazole



Reformer / Reformer Brændselscelle / Fuel cell

El Nat. Gas, Methanol

H2 CO2 CO CO-oprensning

til 0,001 % CO clean-up to 0,001 %

H2 CO2

Varme/heat

Luft ind Air in

Luft ud Air out

Befugtning af luften Humidification of the air



Luft ind Air in

Luft ud Air out

Befugtning af luften Humidification of the air

H2 CO2

H2 CO2 CO CO-oprensning

til 0,001 % CO clean-up to 0,001 %

Reformer / Reformer Brændselscelle / Fuel cell

El Nat. Gas, Methanol

Varme/heat


Integration with methanol reformer


Li Qingfeng et al. Electrochemical and Solid-State Letters, 5 (6) A125-A128 (2002)

Oxygen MeOH +H2O

Pump

Ref

orm

er

200º

C

Condenser

Fuel cell 200ºC



CO tolerance

BA

SF,

Cel

tec®

P11

00W

pro

spec

t



Response to diluted hydrogen

0

50

100

150

200

250

300

350

400

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

0 500 1000 1500Po

wer

den

sity

/ m

W c

m-2

Volta

ge /

V

Current density / mA cm-2

0% CO0.7% CO2.5% CO

Model composition: CO: 0.7%; H2: 34.8%; N2: 64.5% CO: 1.7%; H2: 33.9%; N2: 64.4%

0

50

100

150

200

250

300

350

400

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

0 500 1000 1500

Pow

er d

ensi

ty /

mW

cm

-2

Volta

ge /

V

Current density / mA cm-2

0% CO0.7% CO1.7% CO

λH2 = 1.2 (0.35 mgPt cm-2) λair = 2.0 (0.83 mgPt cm-2)



Dilution of hydrogen with CO λ(air): 2, λ(H2): 1.5 Cathode: 1.3 mgPt cm-2 Anode: 1.3 mgPt cm-2.

100% H2

1%CO;99%H2

1%CO;20%H2

(160ºC)

100% H2

1%CO;99%H2 1%CO;20%H2



High surface adsorption, Langmuir Equilibrium:

or: θθ NkPNk da =− )1(

KPKP

Pkk

Pkk

d

a

d

a

+=

+=

11θ

K = K(T)

N: no. of sites θ: surface fraction occupied P: pressure t: time ka, kd: rate constants for adsorption and desorption

kd

ka

Catalyst

Cov

erag

e

Activity (pressure)

Higher reactant partial pressure

⇓ higher reaction rate

(current) At any given polarization



Competition with CO

H2 coverage CO coverage

Langmuir basis for H2 Langmuir basis for CO

cba


0 200 400 600 800 1000 1200 1400 16000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0 Pure H2 at 1 h 0.2 ppm H2S at 2 h 0.5 ppm H2S at 4 h 1 ppm H2S at 6 h 2 ppm H2S at 7 h 5 ppm H2S at 10 h 10 ppm H2S at 12 h 20 ppm H2S at 13 h 50 ppm H2S at 14 h Pure H2 at 22 h

Cel

l pot

entia

l (V

)

Current density (mA/cm²)

160 °C, 1 mg/cm² Pt/C, λH2=1.2, λair=2



0 200 400 600 800 1000 1200 1400 16000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0 Day 2, pure H2

Day 2 + 2 hours, 2 ppm H2S Day 2 + 7 hours, 2 ppm H2S Day 3, 2 ppm H2S Day 4, 2 ppm H2S Day 5, 2 ppm H2S Day 5 + 2 hours, pure H2

Day 6, pure H2, stable

Cel

l pot

entia

l (V

)

Current density (mA/cm²)

160 °C, 1 mg/cm² Pt/C, λH2=1.2, λair=2




Reduction of binder

Experiments say: Less binder (PBI) gives better performance. What is the optimum/minimum?

What happens if we go to the extreme and make electrode completely without the binder? 1. Nothing. The binder is not needed 2. The catalyst layer falls off too easily 3. The proton transport is mostly blocked 4. Reduction to a certain level improved performance and then

it breaks down



Single cell dev., binderless electrodes

Ultrasonic stirring

(1 hour)

Ultrasonic spraying d=13cm

Flow rate=0.25ml/min Catalytic suspension

Catalytic deposit

New ink

Pt/C Ethanol

Ultrasonic stirring

(24 hours)

Catalytic suspension

Catalytic deposit

Standard ink

Pt/C H3PO4 PBI

Formic acid

Ultrasonic spraying d=13cm

Flow rate=0.25ml/min



Binderless electrodes

S. M

artin

, Q. L

i, T.

Ste

enbe

rg, J

.O. J

ense

n.

J. P

ower

Sou

rces

272

(201

4) 5

59-5

66

H2/Air, 160°C



Binderless electrodes

S. M

artin

, Q. L

i, T.

Ste

enbe

rg, J

.O. J

ense

n.

J. P

ower

Sou

rces

272

(201

4) 5

59-5

66

H2/Air, 160°C



Reducing Pt loading on anode

S. M

artin

, Q. L

i, T.

Ste

enbe

rg, J

.O. J

ense

n.

J. P

ower

Sou

rces

272

(201

4) 5

59-5

66



Reducing Pt loading on cathode

S. M

artin

, Q. L

i, T.

Ste

enbe

rg, J

.O. J

ense

n.

J. P

ower

Sou

rces

272

(201

4) 5

59-5

66



Reducing Pt loading to 0.1 mgPt /cm2 (each)

S. M

artin

, Q. L

i, J.

O. J

ense

n.

J. P

ower

Sou

rces

293

(201

5) 5

1-56

No markers: SOA, 0.6/0.6 mg Markers: 0.1/0.1 mg



Reducing Pt loading to 0.1 mgPt /cm2

S. M

artin

, Q. L

i, J.

O. J

ense

n.

J. P

ower

Sou

rces

293

(201

5) 5

1-56



A closer look a the catalyst materials (JM) Pt on carbon / wt.% 10 20 40 60

Pt loading cathode/anode / mg cm-2 0.098/0.094 0.098/0.094 0.098/0.096 0.098/0.098

Peak power densitya / mW cm-2 321(482) 301 268 215

Pt utilizationa / kWgPt-1

overall cathodic

1.67(2.51) 3.27(4.92)

1.57 3.08

1.38 2.73

1.10 2.19

Voltage at 200 mA cm-2,a / V 0.557(0.618) 0.544 0.513 0.489

Catalyst layer thickness / μm ~ 18 ~ 8 ~ 3.5 ~ 2.5

Pt XRD crystallite sizeb / nm 2.5 2.7 3.3 3.2



Partial flooding?



Acknowledgement

" Development of Auxiliary Power Unit for Recreational

yachts “ (PURE)

Grant agreement no: 303457

Seventh Framework Programme

Book, Springer 2015

Documents

Development of high temperature PEM fuel cells ... · high temperature PEM fuel cells. Simplification and CO tolerance mapping Jens Oluf Jensen, Santiago Martin, Anton Vassiliev,