Fuel Cells…

… any challenges left?

Anna Martinelli Applied Surface Chemistry Chalmers University of Technology anna.martinelli@chalmers.se

Outline

Technical aspects Developments in PEM materials Current future challenges

Li-ion Batteries and Fuel Cells: a comparison

Li-ion BATTERIES

H+

PEM FUEL CELL

Anode Cathode Electrolyte

M. Armand et al., Nature Materials, 8, 2009

Li+

H+

PEM FUEL CELL

Anode Cathode Electrolyte

Fuel Cells: technical aspects

Anode (ox.): H2 2H+ + 2e- Cathode (red.): 2e- + 2H+ + 1/2O2 H2O Net: H2 + 1/2O2 H2O

H+

PEM FUEL CELL

Anode Cathode Electrolyte

Fuel Cells: technical aspects

Anode (ox.): H2 2H+ + 2e- Cathode (red.): 2e- + 2H+ + 1/2O2 H2O Net: H2 + 1/2O2 H2O

OCVth = 1.23 V OCVreal = 0.7-0.9 V

H+

PEM FUEL CELL

Anode Cathode Electrolyte

Fuel Cells: technical aspects

Anode (ox.): H2 2H+ + 2e- Cathode (red.): 2e- + 2H+ + 1/2O2 H2O Net: H2 + 1/2O2 H2O

OCVth = 1.23 V OCVreal = 0.7-0.9 V Key figures: i: mA/cm2 Power: i*V=mW/cm2

Specific Power: W/kg Cost: US$/kW - Bipolar plates to connect FCs in series and achieve the desired power: stacks

PEM FUEL CELL

Fuel Cells: technical aspects

Anode (ox.): H2 2H+ + 2e- Cathode (red.): 2e- + 2H+ + 1/2O2 H2O Net: H2 + 1/2O2 H2O

OCVth = 1.23 V OCVreal = 0.7-0.9 V Key figures: i: mA/cm2 Power: i*V=mW/cm2

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

Wei

ght

Energy

Battery

Fuel Cell

*but also airplanes (Boeing), scooters, etc.

Transport sector: Hybrid vehicles* Both Fuel Cell and Li-ion battery (FCEV) Honda FCX

Li-ion Batteries and Fuel Cells: complementary not mutually exclusive

1999 HONDA FCX-V1 (H2) 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 ≈115 km/kg of H2 + innovative cockpit

The Honda FCX hybrid vehicle

- World Green Car of the Year – 2009 - 2008 Good Design Award from the Japan Industrial Design Promotion Organization - Most important car for 100 years (BBC)

PEM Fuel Cell: applications

Power

Fuel Cell

*Site: CEA (Saclay) Manufacturer: HELION, 2006

Scooter 5 kW

Aviation 20-75 kW

Transport. (cars) Audi Q5 ≈90 kW

Stationary Power Generation* 5-250 kW

Brewery (CA) 250 kW

Portable Power

15-30 W

Fuel Cells: Development programs

http://www1.eere.energy.gov/hydrogenandfuelcells/accomplishments.html

U.S. DOE Multi-years development program for the Fuel Cell technology Costs reduce catalyst (Pt) loading on electrodes Efficiency reduce fuel crossover, increase catalyst selectivity/tolerance to impurities Integration reduce size and weight Durability PEM performance (conductivity, chemical stability, …)

<2000 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Cum

ulat

ive

num

ber o

f Co

mm

erci

al T

echn

olog

ies

30 25 20 15 10 5 0

Fuel Cells H2 Production/Delivery H2 Storage

Accelerating commercialization

Target $30/kW

300 250 200 150 100 50 0 2002 2006 2007 2008 2009 2010 2011 2017

FC sy

stem

cost

/ $/

kW

$275/kW

$108/kW $94/kW

$73/kW $61/kW

$51/kW $49/kW

Initial estimate Balance of plant Stack

Projected Transportation Fuel Cell System Cost

Develop new electrolyte materials and materials’ support

Fuel Cells: PEM materials Nafion the archetypical PEM electrolyte

Perfluorinated backbone

Acidic/hydrophilic termination

proton

Reproduced from: K.D. Kreuer, J. Memb. Sci., 185 (2001)

To be functional a PEM should provide: - Protons - Open channels - Medium that transports protons - …

Fuel Cells: PEM materials - conductivity Nafion

U.S. DOE: σ > 10-1 Scm-1 @ T > 120 °C

Fuel Cells: PEM materials - conductivity Nafion

Benzimidazole ∧

Imidazole -

Poly-benzimidazole

Fuel Cells: PEM materials - conductivity Nafion

Benzimidazole ∧

Imidazole -

Poly-benzimidazole Ionic Liquids

Fuel Cells: PEM materials – Ionic Liquids

- Non-volatile molecular salts - Very low Tm - Protic - Designer solvents An infinite variation of cation:anion structural pairs

Fuel Cells: PEM materials – Ionic Liquids

Triethylammonium methane sulfonate

- Non-volatile molecular salts - Very low Tm - Protic - Designer solvents An infinite variation of cation:anion structural pairs

C. Iojoiu et al., Polym. Adv. Technol., 19, 2008, 1406-1414

Fuel Cells: PEM materials – Ionic Liquids

- Non-volatile molecular salts - Very low Tm - 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, 1406-1414

Fuel Cells: PEM materials – Ionic Liquid derived materials

Fuel Cells: PEM materials – Ionic Liquid derived materials

Swelled polymer membranes i.e. Nafion

Decent conductivities: 10-2–10-1 Scm-1 @ max 190 °C Drawback: Weak mechanical properties

Fuel Cells: PEM materials – Ionic Liquid derived materials

Swelled polymer membranes i.e. Nafion

Decent conductivities: 10-2–10-1 Scm-1 @ max 190 °C Drawback: Weak mechanical properties

A. Martinelli et al., Fuel Cells, 2011, doi: 10.1002/fuce.201100098

Nanoconfine Ionic Liquids: in SiO2 - Ionogels

Good conductivities: > 10-1 Scm-1 @ ≈ 200 °C

glass-like gel-like Ionic Liquid concentration

aLe Bideau et al., PCCP, 9(40), 2007 bNeouze et al., Chem. Mater., 18, 2006 Shimano et al., Chem. Mater., 2007, 19, 5216-5221 Ueno et al., JPC B, 2008, 112, 9013-9019

Fuel Cells: PEM materials – Ionic Liquid derived materials

Fuel Cells: PEM materials – Ionic Liquid derived materials

Nanoconfine Ionic Liquids: in SiO2 - Ionogels

Good conductivities: > 10-1 Scm-1 @ ≈ 200 °C

glass-like gel-like Ionic Liquid concentration

A. Martinelli et al., in manuscript for PCCP, 2012 Shimano et al., Chem. Mater., 2007, 19, 5216-5221 Ueno et al., JPC B, 2008, 112, 9013-9019

Eller eget

Liquid-like properties in solid-like materials

tgel

Time-resolved 1H NMR spectra of ionogel

time

Fuel Cells: Future Challenges

Brewery-Fuel Cell

PEM Materials Are Ionic-Liquid derived materials really the most promising?

They are at least the most intensively investigated …

Fuel Cells: Future Challenges

Micro Fuel-Cell

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

- 300 mW/cm2 1W/cm2

Fuel Cells: Future Challenges

Brewery Fuel-Cell

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: - intra-researchers - with established companies

Fuel Cells: Future Challenges

Commercialization Delicately dependent on available infrastructure (transport sector)

"Honda sees mass production of Fuel-Cell cars possible by 2018”. (Green Car Congress)

Applications: Fuel cell Battery 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)

http://www.fuelcells.org/info/charts/specialty.pdf For applications and type of fuel cells Also http://www.fuelcells.org/info/pubs.html

Fuel cells nanotechnology applications http://www.understandingnano.com/fuel-cells.html

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)

DOE fuel cell requirements http://www1.eere.energy.gov/hydrogenandfuelcells/accomplishments.html See also http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/iphe_commercialization2010.pd See also news from Vätgas Sverige I mina mails. http://techon.nikkeibp.co.jp/NEA/archive/200208/200149/

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)

Fuel Cells: some theoretical aspects

Cell durability: 400-1200 cycles/ years? as long as it is fueled Cell Voltage: 3.6 0.7-0.9 (of 1.23 th.) Specific energy: 100-250 Wh/kg Specific power: 250-340 W/kg 5W/kg (for <2W) 15W/kg (for 10-50W)

H22H+ + 2e- 2e- + 2H+ + 1/2O2 H2O H2 + 1/2O2 H2O (+ heat) The voltage of this reaction is 1.23 V (real 0.7-0.9 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?