新能源材料与技术Renewable Energy: Materials and TechnologiesL6: Hydrogen Fuel Cells1:Basic Principles, Thermodynamics & Electrodics2: Performance Characteristics3:Engineering & Materials ChallengesDr Yimin Chaoy.chao@uea.ac.ukwww.uea.ac.uk/chemistry/people/faculty/chao
新能源材料与技术 Renewable Energy: Materials and Technologies L6: Hydrogen Fuel Cells 1:Basic Principles, Thermodynamics & Electrodics 2: Performance Characteristics 3:Engineering & Materials Challenges Dr Yimin Chao y.chao@uea.ac.uk www.uea.ac.uk/chemistry/people/faculty/chao
HydrogenFuel Cells1:BasicPrinciples,Thermodynamics&Electrodics
Hydrogen Fuel Cells 1:Basic Principles, Thermodynamics & Electrodics
BasicEnergyDevicesAbatterystoreselectrical energyaschemicalenergyNegativeplate:PbSO4+H++2e-+Pb+HSO4DilutePbsoPbSOPbO2H2SO4(aq)Pb→PbO+HSO-+3H++2ePositiveplate:PbSO4+2H,OH2SO4FullydischargedFully chargedAnelectrolyzerconvertselectrical energyintochemical energy (fuel)CathodeAnodeNegativeelectrode:2H++2e-HPositiveelectrode:H,0-→2H++2e-+1/20vdrOxvoOverall:H,0-→H,+1/202ahhStandard Electrolysis
Basic Energy Devices • A ba#ery stores electrical energy as chemical energy. • An electrolyzer converts electrical energy into chemical energy (fuel). Negative plate: PbSO4 + H+ + 2e– Pb + HSO4 – Positive plate: PbSO4 + 2H2O PbO2 + HSO4 – + 3H+ + 2e– Fully charged Fully discharged Negative electrode: 2H+ + 2e– H2 Positive electrode: H2O 2H+ + 2e– + 1/2O2 Overall: H2O H2 + 1/2O2
BasicEnergyDevicesAfuel cell converts chemical energyinto electrical energy-(the reverseofanelectrolyzer).LoadH.ONegativeelectrode:1/2O+2e-+2H+Positiveelectrode:H,→2H++2e-Overall:H2+1/202H,OH2H,0cathanodeelectrolyteAllofthesedevicesthereforeinvolveelectrochemicalreactions!
Basic Energy Devices • A fuel cell converts chemical energy into electrical energy – (the reverse of an electrolyzer). • All of these devices therefore involve electrochemical reacGons! Negative electrode: 1/2 O2 + 2e– + 2H+ H2O Positive electrode: H2 2H+ + 2e– Overall: H2 + 1/2O2 H2O
Typesof Fuel CellsTheconcept of a fuel cell is“deceptively”simple!: Any fuel (chemical energy source) can be"burned"in oxygen.Instead of combusting thefuel togenerateheat energy,onesimplyperforms"cold"combustionvia 2 electrochemical“half-reactions"to generate electrical energy
Types of Fuel Cells • The concept of a fuel cell is “decepGvely” simple! • Any fuel (chemical energy source) can be “burned” in oxygen. • Instead of combusGng the fuel to generate heat energy, one simply performs “cold” combusGon via 2 electrochemical “halfreacGons” to generate electrical energy