Fuel Cells. any challenges left? Anna Martinelli Applied Surface Chemistry Chalmers University of Technology

Transcription

1 Fuel Cells any challenges left? Anna Martinelli Applied Surface Chemistry Chalmers University of Technology

2 Outline Technical aspects Developments in PEM materials Current future challenges

3 Li-ion Batteries and Fuel Cells: a comparison Li-ion BATTERIES PEM FUEL CELL Li + H + M. Armand et al., Nature Materials, 8, 2009 Anode Cathode Electrolyte

4 Fuel Cells: technical aspects Anode (ox.): H 2 2H + + 2e - Cathode (red.): 2e - + 2H + + 1/2O 2 H 2 O PEM FUEL CELL Net: H 2 + 1/2O 2 H 2 O H + Anode Cathode Electrolyte

5 Fuel Cells: technical aspects Anode (ox.): H 2 2H + + 2e - Cathode (red.): 2e - + 2H + + 1/2O 2 H 2 O PEM FUEL CELL Net: H 2 + 1/2O 2 H 2 O OCV th = 1.23 V OCV real = V H + Anode Cathode Electrolyte

6 Fuel Cells: technical aspects Anode (ox.): H 2 2H + + 2e - Cathode (red.): 2e - + 2H + + 1/2O 2 H 2 O PEM FUEL CELL Net: H 2 + 1/2O 2 H 2 O OCV th = 1.23 V OCV real = V Key figures: i: ma/cm 2 Power: i*v=mw/cm 2 Specific Power: W/kg Cost: US$/kW H + - Bipolar plates to connect FCs in series and achieve the desired power: stacks Anode Cathode Electrolyte

7 Fuel Cells: technical aspects Anode (ox.): H 2 2H + + 2e - Cathode (red.): 2e - + 2H + + 1/2O 2 H 2 O PEM FUEL CELL Net: H 2 + 1/2O 2 H 2 O OCV th = 1.23 V OCV real = V Key figures: i: ma/cm 2 Power: i*v=mw/cm 2 Specific Power: W/kg Cost: US$/kW - Bipolar plates to connect FCs in series and achieve the desired power: stacks a few W <---> 1100 kw

8 Li-ion Batteries and Fuel Cells: complementary not mutually exclusive Battery Weight Transport sector: Hybrid vehicles* Both Fuel Cell and Li-ion battery (FCEV) Honda FCX Fuel Cell Energy *but also airplanes (Boeing), scooters, etc.

9 The Honda FCX hybrid vehicle 1999 HONDA FCX-V1 (H 2 ) HONDA FCX-V1 (methanol) Prototype 2002 HONDA FCX PEMFC 86 kw 2006 HONDA FCX Concept PEMFC 100 kw Smaller/lighter +3 electric motors (driving front and rear wheels) 2008-present HONDA FCX Clarity PEMFC 100 kw - World Green Car of the Year Good Design Award from the Japan Industrial Design Promotion Organization - Most important car for 100 years (BBC) 115 km/kg of H 2 + innovative cockpit

10 PEM Fuel Cell: applications Portable Power W Scooter 5 kw Aviation kw Transport. (cars) Audi Q5 90 kw Fuel Cell Stationary Power Generation* kw Brewery (CA) 250 kw Power *Site: CEA (Saclay) Manufacturer: HELION, 2006

11 Fuel Cells: Development programs U.S. DOE Costs Efficiency Integration Durability Multi-years development program for the Fuel Cell technology reduce catalyst (Pt) loading on electrodes reduce fuel crossover, increase catalyst selectivity/tolerance to impurities reduce size and weight PEM performance (conductivity, chemical stability, ) Accelerating commercialization Projected Transportation Fuel Cell System Cost Cumulative number of Commercial Technologies Fuel Cells H 2 Production/Delivery H 2 Storage FC system cost / $/kw $275/kW Initial estimate Balance of plant Stack $108/kW Target $94/kW $30/kW $73/kW $61/kW $51/kW $49/kW 0 < Develop new electrolyte materials and materials support

12 Fuel Cells: PEM materials Nafion the archetypical PEM electrolyte To be functional a PEM should provide: - Protons - Open channels - Medium that transports protons - proton Perfluorinated backbone Acidic/hydrophilic termination Reproduced from: K.D. Kreuer, J. Memb. Sci., 185 (2001)

13 Fuel Cells: PEM materials - conductivity Nafion U.S. DOE: σ > 10-1 Scm T > 120 C

14 Fuel Cells: PEM materials - conductivity Nafion Imidazole - Benzimidazole Poly-benzimidazole

15 Fuel Cells: PEM materials - conductivity Nafion Imidazole - Benzimidazole Poly-benzimidazole Ionic Liquids

16 - Non-volatile molecular salts - Very low T m - Protic - Designer solvents An infinite variation of cation:anion structural pairs Fuel Cells: PEM materials Ionic Liquids

17 Fuel Cells: PEM materials Ionic Liquids - Non-volatile molecular salts - Very low T m - Protic - Designer solvents An infinite variation of cation:anion structural pairs Triethylammonium methane sulfonate C. Iojoiu et al., Polym. Adv. Technol., 19, 2008,

18 Fuel Cells: PEM materials Ionic Liquids - Non-volatile molecular salts - Very low T m - Protic - Designer solvents An infinite variation of cation:anion structural pairs Dilemma: ionic liquids are liquid! Triethylammonium methane sulfonate C. Iojoiu et al., Polym. Adv. Technol., 19, 2008,

19 Fuel Cells: PEM materials Ionic Liquid derived materials

20 Fuel Cells: PEM materials Ionic Liquid derived materials Swelled polymer membranes i.e. Nafion Decent conductivities: Scm max 190 C Drawback: Weak mechanical properties

21 Fuel Cells: PEM materials Ionic Liquid derived materials Swelled polymer membranes i.e. Nafion Decent conductivities: Scm max 190 C Drawback: Weak mechanical properties A. Martinelli et al., Fuel Cells, 2011, doi: /fuce

22 Fuel Cells: PEM materials Ionic Liquid derived materials Nanoconfine Ionic Liquids: in SiO 2 - Ionogels Good conductivities: > 10-1 Scm 200 C glass-like gel-like Ionic Liquid concentration a Le Bideau et al., PCCP, 9(40), 2007 b Neouze et al., Chem. Mater., 18, 2006 Shimano et al., Chem. Mater., 2007, 19, Ueno et al., JPC B, 2008, 112,

23 Fuel Cells: PEM materials Ionic Liquid derived materials Nanoconfine Ionic Liquids: in SiO 2 - Ionogels Liquid-like properties in solid-like materials time Good conductivities: > 10-1 Scm 200 C Eller eget t gel Time-resolved 1 H NMR spectra of ionogel glass-like gel-like Ionic Liquid concentration A. Martinelli et al., in manuscript for PCCP, 2012 Shimano et al., Chem. Mater., 2007, 19, Ueno et al., JPC B, 2008, 112,

24 Fuel Cells: Future Challenges PEM Materials Are Ionic-Liquid derived materials really the most promising? They are at least the most intensively investigated Brewery-Fuel Cell

25 Fuel Cells: Future Challenges Micro Fuel-Cells The research on Fuel Cells is going towards miniaturization. Applications in microelectronics industry - Implementation of silicon-chip fabrication techniques - Hydrogen generation from chemical hydrides mw/cm 2 1W/cm 2 Micro Fuel-Cell

26 Fuel Cells: Future Challenges Synergies The Brewery-integrated Fuel Cell power generation is a good example of governmental incentive in technological development. In Sweden this kind of synergies must be stimulated. Collaborations: Brewery Fuel-Cell - intra-researchers - with established companies

27 Fuel Cells: Future Challenges "Honda sees mass production of Fuel-Cell cars possible by (Green Car Congress) Commercialization Delicately dependent on available infrastructure (transport sector)

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33 g/info/charts/specialty. pdf For applications and type of fuel cells Applications: Fuel cell Stationary power generation Breweries/wineries Battery Also g/info/pubs.html Transportation (cars, buses, scooters, APU, planes (Boeing is developing a fuel cell plane)) Portable power (back-up systems, military) Micro power (consumer electronics) Fuel cells nanotechnology applications

34 Compare Li-ion batteries (talks before) with fuel cells. Complementary? Energy/costs/commercialization? Cronological short story of the FC? Hystogram of published papers? Interesting trends between #articles and funding? Cronological of the types of materials used as electrolytes? What are hot materials now? What are governmental programs sustaining? And in which countries? Pilot programs? When will we have FC in transport sector? Ex of Volvo trucks What kind of research is most hot now? In situ? Green? Microcells for medical applications? (not only transport)

35 DOE fuel cell requirements See also See also news from Vätgas Sverige I mina mails.

36 Applications: Fuel cell Stationary power generation Breweries/wineries Transportation (cars, buses, scooters, APU, planes (Boeing is developing a fuel cell plane)) Portable power (back-up systems, military) Micro power (consumer electronics: laptops, cellular phones)

37 Fuel Cells: some theoretical aspects H 2 2H + + 2e - 2e - + 2H + + 1/2O 2 H 2 O H 2 + 1/2O 2 H 2 O (+ heat) The voltage of this reaction is 1.23 V (real V due to?) Comes from? Normal current from one cell is? Therefore for real applications we need stacks, the voltage becomes additive. How is power defined? Typical U-I curves? Cell durability: cycles/ years? as long as it is fueled Cell Voltage: (of 1.23 th.) Specific energy: Wh/kg Specific power: W/kg 5W/kg (for <2W)