Development of high temperature PEM fuel cells. Simplification and CO tolerance mapping

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1 Downloaded from orbit.dtu.dk on: Jul 07, 2018 Development of high temperature PEM fuel cells. Simplification and CO tolerance mapping Jensen, Jens Oluf; Fernandez, Santiago Martin; Vassiliev, Anton; Cleemann, Lars Nilausen; Li, Qingfeng Publication date: 2015 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Jensen, J. O., Fernandez, S. M., Vassiliev, A., Cleemann, L. N., & Li, Q. (2015). Development of high temperature PEM fuel cells. Simplification and CO tolerance mapping [Sound/Visual production (digital)]. PURE Workshop: Neptune's Hydrogen and Fuel cells, Naples, Italy, 15/12/2015 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

2 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 DK-2800 Lyngby Denmark

3 Outline The choice of fuel CO effect on the PEM fuel cell Binderless electrodes Lowering the platinum loading

4 Fueling of fuel cells Fuel Reforming Purification Fuel cell Type I Hydrogen LT PEMFC Type II Methanol Dimethyl ether Simple reformer Purification Type III Natural gas Gasoline/diesel LPG Ethanol Complex reformer HT-PEMFC

5 Fueling of fuel cells Fuel efficency Systme simplicity Availability Ease of storage Hydrogen Methanol HC Type I Hydrogen Type II Methanol Dimethyl ether Type III Natural gas Gasoline/diesel LPG Ethanol

6 AFC (H + via OH - ) FC temperatures PEMFC (H + ) PAFC (H + ) Low temperature fuel cells Intermediate temperature fuel cells? High temperature fuel cells MCFC (O 2- as CO 3 2- ) SOFC (O 2- ) RT 100ºC 200ºC 600ºC 1000ºC

7 Results with PBI membranes Polybenzimidazole H N N H N N n Poly (2,2 -m-(phenylene)-5,5 -bibenzimidazole) Well-known temperature resistant polymer T g = ~430ºC When doped with phosphoric acid: Proton conductor Wainright and Savinell. J. Electrochem. Soc. 142 (1995) L121

8 Reformer / Reformer Brændselscelle / Fuel cell Nat. Gas, Methanol El Varme/heat CO-oprensning til 0,001 % CO clean-up to 0,001 % H 2 CO 2 CO H 2 CO 2 Luft ind Air in Luft ud Air out Befugtning af luften Humidification of the air

9 Reformer / Reformer Brændselscelle / Fuel cell Nat. Gas, Methanol El Varme/heat CO-oprensning til 0,001 % CO clean-up to 0,001 % H 2 CO 2 CO H 2 CO 2 Luft ind Air in Luft ud Air out Befugtning af luften Humidification of the air

10 Integration with methanol reformer Condenser MeOH +H 2 O Reformer 200ºC Fuel cell 200ºC Oxygen Pump Li Qingfeng et al. Electrochemical and Solid- State Letters, 5 (6) A125-A128 (2002)

11 CO tolerance BASF, Celtec P1100W prospect

12 Response to diluted hydrogen Voltage / V 1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0% CO 0.7% CO 2.5% CO Power density / mw cm -2 Voltage / V 1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0% CO 0.7% CO 1.7% CO Power density / mw cm Current density / ma cm Current density / ma cm -2 Model composition: CO: 0.7%; H 2 : 34.8%; N 2 : 64.5% CO: 1.7%; H 2 : 33.9%; N 2 : 64.4% λ H2 = 1.2 (0.35 mg Pt cm -2 ) λ air = 2.0 (0.83 mg Pt cm -2 )

13 Dilution of hydrogen with CO λ(air): 2, λ(h 2 ): 1.5 Cathode: 1.3 mg Pt cm -2 Anode: 1.3 mg Pt cm -2. (160ºC) 100% H 2 1%CO;99%H 2 1%CO;20%H 2 100% H 2 1%CO;20%H 2 1%CO;99%H 2

14 High surface adsorption, Langmuir k a k d k Equilibrium: PN(1 θ ) k Nθ a = or: d Catalyst θ = ka P kd ka 1+ P k d = KP 1+ KP Coverage Activity (pressure) Higher reactant partial pressure higher reaction rate (current) At any given polarization N: no. of sites θ: surface fraction occupied P: pressure t: time k a, k d : rate constants for adsorption and desorption K = K(T)

15 Competition with CO Langmuir basis for H 2 Langmuir basis for CO a b c H 2 coverage CO coverage

16 Cell potential (V) 160 C, 1 mg/cm² Pt/C, λ H2 =1.2, λ air =2 1.0 Pure H 2 at 1 h 0.2 ppm H 2 S at 2 h ppm H 2 S at 4 h ppm H 2 S at 6 h 2 ppm H 2 S at 7 h ppm H 2 S at 10 h ppm H 2 S at 12 h 20 ppm H 2 S at 13 h 50 ppm H 2 S at 14 h Pure H 2 at 22 h Current density (ma/cm²)

17 Cell potential (V) C, 1 mg/cm² Pt/C, λ H2 =1.2, λ air =2 Day 2, pure H 2 Day hours, 2 ppm H 2 S Day hours, 2 ppm H 2 S Day 3, 2 ppm H 2 S Day 4, 2 ppm H 2 S Day 5, 2 ppm H 2 S Day hours, pure H 2 Day 6, pure H 2, stable Current density (ma/cm²)

18 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

19 Single cell dev., binderless electrodes Pt/C PBI H 3 PO 4 Formic acid Standard ink Ultrasonic Ultrasonic spraying stirring d=13cm (24 hours) Catalytic Flow rate=0.25ml/min suspension Catalytic deposit Pt/C Ethanol New ink Ultrasonic stirring (1 hour) Catalytic suspension Ultrasonic spraying d=13cm Flow rate=0.25ml/min Catalytic deposit

20 Binderless electrodes H 2 /Air, 160 C S. Martin, Q. Li, T. Steenberg, J.O. Jensen. J. Power Sources 272 (2014)

21 Binderless electrodes H 2 /Air, 160 C S. Martin, Q. Li, T. Steenberg, J.O. Jensen. J. Power Sources 272 (2014)

22 Reducing Pt loading on anode S. Martin, Q. Li, T. Steenberg, J.O. Jensen. J. Power Sources 272 (2014)

23 Reducing Pt loading on cathode S. Martin, Q. Li, T. Steenberg, J.O. Jensen. J. Power Sources 272 (2014)

24 Reducing Pt loading to 0.1 mg Pt /cm 2 (each) No markers: SOA, 0.6/0.6 mg Markers: 0.1/0.1 mg S. Martin, Q. Li, J.O. Jensen. J. Power Sources 293 (2015) 51-56

25 Reducing Pt loading to 0.1 mg Pt /cm 2 S. Martin, Q. Li, J.O. Jensen. J. Power Sources 293 (2015) 51-56

26 A closer look a the catalyst materials (JM) Pt on carbon / wt.% Pt loading cathode/anode / mg cm / / / /0.098 Peak power density a / mw cm (482) Pt utilization a / kwg Pt -1 overall cathodic 1.67(2.51) 3.27(4.92) Voltage at 200 ma cm -2,a / V Catalyst layer thickness / μm Pt XRD crystallite size b / nm 0.557(0.618) ~ 18 ~ 8 ~ 3.5 ~

27 Partial flooding?

28 Acknowledgement " Development of Auxiliary Power Unit for Recreational yachts (PURE) Grant agreement no: Seventh Framework Programme Book, Springer 2015