Ethanol Fuel as Portable Power Source in Alkaline Fuel CellsProf. Shingjiang Jessie Lue

Chair and professor, Department of Chemical and Materials Engineering

Group leader, Green Technology Research Center

Chang Gung University, Taiwan

Fuel cell cars powered by bioethanol: Green energy

H2 + O2 H2O + i

Chemical energy electricity Oxidation/combustion of

fuels Spontaneous reaction Catalysts speed up reaction

rate (more electrons generated; higher electrical current)

Various process steps for biomass conversion to ethanol and co-products

Badwal et al., Appl. Energ. 145 (2015) 80.

Various sources of ethanol, energy output/ input ratios and commercial statusSource type Sources Energy output/input ratio Commercialization stage

Food crops CornWheatBarleySugarcaneSugar beetCassavaSorghum

Corn: 1.4, 2a and 2.8b

Sugarcane:~8 (Brazil) Sugar beet: 2

Commercial plants of ethanol mainly from corn (US) and sugarcane

Inedible parts of plant-cellulosic ethanol

Corn stoverWheat strawRice strawSugarcane bagasse

5.2–5.545.2–32

Pre-commercial stage, pilot scale or demonstration plants with subsidies and local government support

Cellulosic ethanol-others Switch grassPoplarForest residueAgricultural wasteMunicipality waste

2–36 Pilot scale or demonstration plants with subsidies and local government support

a For ‘‘a dry grind ethanol plant that produces and sells dry distiller’s grains and uses conventional fossil fuel power for thermal energy and electricity’’.b For ‘‘a dry grind ethanol plant that produces and sells dry distiller’s grains and uses’’ 50% biomass power.

Badwal et al., Appl. Energ. 145 (2015) 80.

Potential fuels: hydrogen and alcohols

Badwal et al., Appl. Energ. 145 (2015) 80.

Electrochemical reactions involved in various types of alcohol fuel cells

Badwal et al., Appl. Energ. 145 (2015) 80.

Proton- and hydroxide-conducting DEFCs

C2H5OH + 3O2 → 2 CO2 + 3 H2O Eo=1.14 V, ΔGo= -1325 kJ mol–1

Disadvantages:Ethanol cross-over -- Fuel loss -- Mixed cell potentialExpensive Pt based catalystProton exchange membrane

Advantages:Faster ethanol oxidation rate in alkaline mediaCan use less expensive non-Pt catalystsDirection of OH− anion motion opposes ethanol permeability: less EtOH cross-overEasy water management

C2H5OH + 3O2 → 2 CO2 + 3 H2O Eo=1.14 V, ΔGo= -1325 kJ mol–1

Acid Alkaline

Front. Energy Power Eng. China 4 (2010) 443; J. Membr. Sc. 367 (2011) 256.

Electrochemical performance

Polarization curve (V-I curve)

Voc (open-circuit voltage): governed by catalytic activity and fuel cross-over rate

Ohmic loss: governed by cell electric resistance (esp. membrane electrolyte)

Power density curve (P-I curve)

P=VI

Pmax (peak power density): more reproducible than Voc

Pmax: indicator of fuel cell performance

http://www.intechopen.com/

DEFC performance reported in literatures

An et al., Renew. Sust. Energ. Rev. 50 (2015) 1462.

DEFC prototype stack

Badwal et al., Appl. Energ. 145 (2015) 80.

10 kW DEFC stack (by NDC Power)1 kW DEFC stack (by NDC Power)

Our Research Focuses

Prepare and synthesize frontier materials for energy applicationsSolar cell

Fuel cell

Lithium-air battery Membrane Requirements : High conductivity and low fuel permeability

Working Mechanism of Alkaline Alcoholic Fuel Cells

O2+H2O

CO2+H2O

C2H5OH+KOH

Nanocomposite Membrane

C2H5OH

Anode: C2H5OH+12OH-→2CO2+9H2O+12e-

Cathode: 3O2+6H2O+12e-→12OH- Overall: C2H5OH+3O2→2CO2+3H2O

Hydroxide transport mechanisms

Vehicular diffusion

Hopping mechanism

Surface diffusion

Polymer/nano-fillersPolymer/carbon nano-tubesPolymer/anion-

exchange moiety

Our Membrane Electrolyte Development Strategy

PVA/CNTPBI/CNT

Q-PVA/Q-chitosan

Blend with Q-chitosannanoparticles

J. Polym. Sci. Phys. 51 (2013) 1779J. Membr. Sci. 376 (2011) 225J. Power Sources 202 (2012) 1J. Power Sources 246 (2014) 39

J. Membr. Sci. 485 (2015) 17

Nafion/GOPBI/GO

J. Membr. Sci. 493 (2015) 212

Pristine GO

GO on Nafion

Single cell assembly and test

MEA (membrane electrode assembly) Anode (catalyst on gas diffusion electrode): Pt-Ru/C or non-Pt/C on carbon cloth Membrane electrolyte Cathode (catalyst on gas diffusion electrode): Pt/C or non-Pt on carbon cloth

Fuel/KOH

J. Membr. Sci. 464 (2014) 43.

DEFC performance: PTFE/sSEBS

DEFC at 30 and 60ºC

Pmax = 17 mW cm-2

at 30ºC

at 60ºC

Pmax = 7.6 mW cm-2

Anode: PtRu/C (6 mg cm-2)Cathode: Pt/C (5 mg cm-2)

Sulfonated styrene-ethylene-butylene-styrene block copolymer

J. Membr. Sci. 493 (2015) 212.3 M ethanol at 80ºC

DEFC performance: Graphene oxide (GO)/Nafion

Pmax = 35 mW cm-2

Anode: PtRu/C (6 mg cm-

2)Cathode: Pt/C (5 mg cm-

2)

(a)

(b)

(c)

(d)

ADEFC performance: polyvinyl alcohol/carbon nanotubes (PVA/CNT)

ADEFC in 5 M KOH

at 30ºC

PVA/CNT

at 60ºC

J. Power Sources, in review.

Fractional free volume: 2.48 to 3.53% (containing CNT)

Pmax = 33 mW cm-2 Pmax = 65 mW cm-2

Anode: PtRu/C (6 mg cm-2), cathode: Pt/C (5 mg cm-2)

J. Membr. Sci. 485 (2015) 17.3 M ethanol in 5 M KOH

Anode: PtRu/C (6 mg cm-2)Cathode: Pt/C (5 mg cm-2)

Anode: PdCeO2/C (6 mg cm-2)Cathode: CuFe/C(5 mg cm-2)

ADEFC performance: Q-PVA/Q-chitosan

EtOH

Pmax = 20 mW cm-2

Pmax = 59 mW cm-2

J. Membr. Sci. In preparation.3 M ethanol in 5 M KOH

ADEFC performance: GO/PBI

Anode: PtRu/C (6 mg cm-2)Cathode: Pt/C (5 mg cm-2)

Anode: PdCeO2/C (6 mg cm-2)Cathode: CuFe/C 5 mg cm-2)

Pt-based catalyst Non Pt-based catalyst

Pmax = 120 mW cm-2 Pmax = 100 mW cm-2

Our Alkaline Fuel Cell Performance

Conclusion Ethanol is a potent fuel source for direct alcohol

fuel cells We have designed various nanocomposite

electrolytes for acidic and alkaline DEFCs Our alkaline DEFC reached peak power density of

120 mW cm-2

Continued investigation on stable, high-performance catalysts on ethanol oxidation and oxygen reduction reactions is in strong demand

An et al., Renew. Sust. Energ. Rev. 50 (2015) 1462.

Acknowledgements

Ministry of Science and Technology, Taiwan Chang Gung Hospital Project Mr. Bor-Chern Yu, Mr. Guan-Ming Liao, Ms. Pin-

Chieh Li, Ms. Jia-Shiun Lin, Dr. Hsieh-Yu Li, Dr. Chao-Ming Shih, Dr. Rajesh Kumar

Thank you for your attention!