電動(dòng)勢(shì)與熱動(dòng)力學(xué)燃料電池

電動(dòng)勢(shì)與熱動(dòng)力學(xué)燃料電池第1頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月Reversibility1)ChemicalReversibilityPtis0.222VmorenegativethanAgShortedExternalbatterychemicallyreversible:Reversingthecellcurrentmerelyreversesthecellreaction.Nonewreactionsappear,thusthecellistermed;chemicallyirreversible:differentelectrodereactionsaswellasadifferentnetprocessuponcurrentreversal;第2頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月ReversibilityThermodynamicallyreversible:whenaninfinitesimalreversalinadrivingforcecausesittoreversedirectionInelectrochemistryIfasystemfollowstheNernstequationoranequationderivedfromit,theelectrodereactionisoftensaidtobethermodynamicallyorelectrochemicallyreversible(ornernstian).第3頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月FreeEnergyandCellemf第4頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月ReductionPotentialsTheprimaryreference,chosenbyconvention,isthenormalhydrogenelectrode(NHE),alsocalledthestandardhydrogenelectrode(SHE):第5頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月emfandConcentration第6頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月ReferenceElectrodes第7頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月第8頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月ImpedanceSpectroscopy(Or,howasinusoidallyvaryingvoltageisused

toprobemultipleelectricalpropertiesofmaterials)第9頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月IntroductionISmeasurestheresistanceofacircuittoanappliedvoltageZ(t)=E(t)/I(t),Z()=E()/I()WhenEisappliedasasinusoidalfunctioninalinearsystem,Iresponsecanberepresentedbyasumofsinusoidalfuctionswithphaseshifts.Ifanequivalentcircuitforthesystembeingprobedcanbeconstructed,thentheresistanceorcapacitancevaluesforeachcircuitelementcanbebackedoutfromZ.Especiallyinelectrochemicalimpendancespectroscopy(EIS),thethevoltageprobesignalissmall(1-10mV)sothecurrentresponseispseudolinear(sidebenefit:itdoesn’tperturbthesampleverymuch)ABardandLFaulkner,ElectrochemicalMethods:FundamentalsandApplications(2000)/G2/Appnotes/Reference/eistheory/theory/EIS_Theory.htm第10頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月Background–ImpedanceandCircuitElementsE(t)=E0cos(

t),=2fI(t)=I0cos(t-)Or,ifonewritesincomplexnotation:E(t)=E0exp(it)I(t)=I0exp(it-i)Z(t)=Z0exp(i)=Z0(cos+isin)E/Iresponseforaresistor(=0)E/Iresponseforacapacitor(=-90)E/Iresponseforaninductor(=90)/G2/Appnotes/Reference/eistheory/theory/EIS_Theory.htmhttp://www.bath.ac.uk/~chsacf/solartron/circp/html/acrci.htm第11頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月

=-jXc=jXlhttp://www.bath.ac.uk/~chsacf/solartron/circp/html/acrci.htmRFormorecomplexcircuits,useKirchoff’srules第12頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月PlottingImpedance

ACole-Cole(orNyquist)plotoftherealandimaginarycomponentsofZ

foracircuitcontainingacapacitorandresistorinparallel(realworld

example:achargedlayerataninterface).=1/=1/RCNamedafterKSColeandRHCole,JChemPhys

9,341(1941)第13頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月PlottingImpedanceABodeplotofacircuitcontainingacapacitorandresistorinparallel.log|Z|andvs.logareplotted,showingexplicitlytheimpactof

impedance./G2/Appnotes/Reference/eistheory/theory/EIS_Theory.htm第14頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月CircuitElementsfromElectrochemistryElectrolyteresistanceDoublelayercapacitance(~30

F/cm2foraqueoussystems)PolarizationresistanceChargetransferresistanceCoatingcapacitance

Constantphaseelement(afudgefactor)Virtualinductor(adsorption?)And…lAWE,RE,CER=l/

A/G2/Appnotes/Reference/eistheory/theory/EIS_Theory.htm第15頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月Diffusion(akaWarburgImpedance)Warburgimpedance=diffusionofchemicalspeciestoalargeplanarelectrodeInfinitediffusionlayerthicknessDiffusionlayerthickness

Also,intheWarburgregion,

=45o/resources/eis/diffusion.htm第16頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月EquivalentCircuitModelforElectrochemicalCells

MixedKinetic+DiffusionmodelCole-ColeplotBodeplot/G2/Appnotes/Reference/eistheory/theory/EIS_Theory.htm第17頁(yè)，課件共18頁(yè)，創(chuàng)作于2023年2月SomeApplicationsofISDeterminecorrosionratesofmaterials*MeasurecapacitanceandresistanceofSAMstoascertainthicknessandpackingqualityProbelinearityofelectrical/electrochemicalreactionsCharacterizeelectricalactivityacrossinterfacestodeterminecarrierconcentration,etc.Determinediffusionrateofcounterionsinconductingpolymer/carbonnanotubecomposite