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Ethanol Fuel as Portable Power Source in Alkaline Fuel Cells

Ethanol Fuel as Portable Power Source in Alkaline Fuel Cells. Prof. 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.

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Ethanol Fuel as Portable Power Source in Alkaline Fuel Cells

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  1. Ethanol Fuel as Portable Power Source in Alkaline Fuel Cells Prof. Shingjiang Jessie Lue Chair and professor, Department of Chemical and Materials Engineering Group leader, Green Technology Research Center Chang Gung University, Taiwan

  2. 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)

  3. Various process steps for biomass conversion to ethanol and co-products Badwal et al., Appl. Energ. 145 (2015) 80.

  4. Various sources of ethanol, energy output/ input ratios and commercial status 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.

  5. Potential fuels: hydrogen and alcohols Badwal et al., Appl. Energ. 145 (2015) 80.

  6. Electrochemical reactions involved in various types of alcohol fuel cells Badwal et al., Appl. Energ. 145 (2015) 80.

  7. Proton- and hydroxide-conducting DEFCs Alkaline Acid C2H5OH + 3O2 → 2 CO2 + 3 H2O Eo=1.14 V, ΔGo= -1325 kJ mol–1 C2H5OH + 3O2 → 2 CO2 + 3 H2O Eo=1.14 V, ΔGo= -1325 kJ mol–1 • Disadvantages: • Ethanol cross-over • -- Fuel loss • -- Mixed cell potential • Expensive Pt based catalyst • Proton exchange membrane • Advantages: • Faster ethanol oxidation rate in alkaline media • Can use less expensive non-Pt catalysts • Direction of OH− anion motion opposes ethanol permeability: less EtOH cross-over • Easy water management Front. Energy Power Eng. China 4 (2010) 443; J. Membr. Sc. 367 (2011) 256.

  8. 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/

  9. DEFC performance reported in literatures An et al., Renew. Sust. Energ. Rev. 50 (2015) 1462.

  10. DEFC prototype stack 1 kW DEFC stack (by NDC Power) 10 kW DEFC stack (by NDC Power) Badwal et al., Appl. Energ. 145 (2015) 80.

  11. Our Research Focuses Prepare and synthesize frontier materials for energy applications Solar cell Nanocomposite Membrane C2H5OH CO2+H2O O2+H2O C2H5OH+KOH Energy Applications Fuel cell Anode: C2H5OH+12OH-→2CO2+9H2O+12e- Cathode: 3O2+6H2O+12e-→12OH- Overall: C2H5OH+3O2→2CO2+3H2O Working Mechanism of Alkaline Alcoholic Fuel Cells Lithium-air battery Membrane Requirements : High conductivity and low fuel permeability

  12. Hydroxide transport mechanisms Vehicular diffusion Hopping mechanism Surface diffusion Polymer/anion-exchange moiety Polymer/carbon nano-tubes Polymer/nano-fillers

  13. Our Membrane Electrolyte Development Strategy Q-PVA/Q-chitosan Pristine GO Nafion/GO PBI/GO Blend with Q-chitosan nanoparticles J. Polym. Sci. Phys. 51 (2013) 1779 J. Membr. Sci. 376 (2011) 225 J. Power Sources 202 (2012) 1 J. Power Sources 246 (2014) 39 GO on Nafion J. Membr. Sci. 485 (2015) 17 PVA/CNT PBI/CNT J. Membr. Sci. 493 (2015) 212

  14. Single cell assembly and test Fuel/KOH 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

  15. DEFC performance: PTFE/sSEBS at 30ºC Pmax = 7.6 mW cm-2 at 60ºC Sulfonated styrene-ethylene-butylene-styrene block copolymer Pmax = 17 mW cm-2 Anode: PtRu/C (6 mg cm-2) Cathode: Pt/C (5 mg cm-2) J. Membr. Sci. 464 (2014) 43. DEFC at 30 and 60ºC

  16. 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) J. Membr. Sci. 493 (2015) 212. 3 M ethanol at 80ºC

  17. ADEFC performance: polyvinyl alcohol/carbon nanotubes (PVA/CNT) Fractional free volume: 2.48 to 3.53% (containing CNT) at 30ºC at 60ºC PVA/CNT Pmax = 33 mW cm-2 Pmax = 65 mW cm-2 J. Power Sources, in review. Anode: PtRu/C (6 mg cm-2), cathode: Pt/C (5 mg cm-2) ADEFC in 5 M KOH

  18. ADEFC performance: Q-PVA/Q-chitosan Anode: PtRu/C (6 mg cm-2) Cathode: Pt/C (5 mg cm-2) EtOH Pmax = 59 mW cm-2 Anode: PdCeO2/C (6 mg cm-2) Cathode: CuFe/C(5 mg cm-2) Pmax = 20 mW cm-2 J. Membr. Sci. 485 (2015) 17. 3 M ethanol in 5 M KOH

  19. ADEFC performance: GO/PBI Non Pt-based catalyst Pt-based catalyst Anode: PdCeO2/C (6 mg cm-2) Cathode: CuFe/C 5 mg cm-2) Anode: PtRu/C (6 mg cm-2) Cathode: Pt/C (5 mg cm-2) Pmax = 120 mW cm-2 Pmax = 100 mW cm-2 3 M ethanol in 5 M KOH J. Membr. Sci. In preparation.

  20. Our Alkaline Fuel Cell Performance

  21. 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.

  22. 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

  23. Thank you for your attention!

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