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Procedures For Performing PEM Single Cell Testing
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FSECs Procedures
For Performing PEM Single Cell Testing
Test protocol for Cell Performance TestsWork Performed Under
DOE Contract # DEFC3606GO16028
April 8, 2009
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EXECUTIVESUMMARY
This document defines, indetail, a test protocol for performing protonexchange membrane(PEM)singlecelltesting. Developmentofthistestprotocol isapartoftherequirementsofFSECs Task 5, Characterize MEA Performance, under DOE Contract #DEFC3606GO16028.ThistestprotocolhasbeenevaluatedandisusedatFSECforsinglecelltesting.Under this contract, FSEC will perform singlecell tests to assess the relative merits of thecandidate membranes that are submitted by the Task 1 team members. These tests will beconductedatoperatingconditionsthatareofinteresttotheDOEand,whereappropriate,willberunusingidenticalproceduresonalltestedcells. Task1teammembersthatarecontinuingbeyond the Go No Go milestone are requested to review this document and identifyconditionsthatareofconcern.FSECwilliteratewiththeseTask1teammemberstoresolvetheseconcernsResearchers following the test protocol will be able to reproduce results that have beenobtainedbyFSEC.
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Contents1.OverviewofFSECsProceduresforPerformingPEMSingleCellTesting...................................6
1.1IntroductionToTheTestProtocolforPEMCellScreeningTest.......................................... 61.2ComponentstobeDelivered............................................................................................... 61.3DetailsoftheCell................................................................................................................. 61.4Membrane,CCM,andGDLThicknessMeasurement.......................................................... 81.5CellAssembly....................................................................................................................... 91.6PreTestIntegrityTest........................................................................................................ 101.7TestsPerformedonEachCell............................................................................................10
1.7.1LinearSweepVoltammetry,CyclicVoltammetry,AndCellConditioning.................101.7.2PerformanceVerificationTest...................................................................................131.7.3PosttestIntegrityTest ...............................................................................................151.7.4PosttestAnalysis....................................................................................................... 151.7.5CellDataReport......................................................................................................... 16
1.8FuelCellHydrogenSafetyPlan..........................................................................................162.DaybyDayPEMMEATestSequence.......................................................................................19
2.1AssembletheCell............................................................................................................... 192.2Day1................................................................................................................................... 192.3Day2................................................................................................................................... 202.4Day3................................................................................................................................... 202.5Day4(at1.5atm)............................................................................................................... 202.6Days5,6,and7(at1.5atm)..............................................................................................212.7Day8(at1.5atm)............................................................................................................... 212.8Day9................................................................................................................................... 22
AppendixA:GurleyNumberProcedure....................................................................................... 23A1ReferenceMaterials............................................................................................................ 23A2Introduction........................................................................................................................ 23A3MaterialsandEquipment................................................................................................... 24
A3.1Materials..................................................................................................................... 24A3.2Equipment................................................................................................................... 24A3.3QualityControl ............................................................................................................25
A4MainGasketPreparation.................................................................................................... 25A5PreparationofSubgaskets ..................................................................................................25A6PreparationofGasDiffusionLayerSamples......................................................................26A7CleaningofFuelCellComponents......................................................................................26A8AssemblyProcedure........................................................................................................... 26A9LeakingCheckProcedure.................................................................................................... 29A10DataProcess...................................................................................................................... 29
A10.1DataSheetGurleyNumberCalculations..................................................................30A11Acceptance........................................................................................................................ 30
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AppendixB:PEMFuelCellUnitCellAssemblyProcedure...........................................................31B1ReferenceMaterials............................................................................................................ 31B2BillofMaterials................................................................................................................... 31
B2.1Materials..................................................................................................................... 31B2.2Equipment................................................................................................................... 31
B3Objectives............................................................................................................................ 32B4GeneralInstructions............................................................................................................ 32B5PreparationforCellAssembly.......................................................................................... 32B6AssemblingtheCellFuelCellTechnology(FCT)HardwareSet.......................................32
AppendixCProcedureforLeakTestingaSingleCellAfterAssembly..........................................34C1ExternalLeakTest............................................................................................................... 34
C1.1Procedure ....................................................................................................................34C2InternalLeakTest................................................................................................................ 35
C2.1ProcedureforInternalLeakTest................................................................................. 35AppendixDPEMFCUnitCellTest .................................................................................................37
D1ReferenceMaterials........................................................................................................... 37D2BillofMaterials................................................................................................................... 37
D2.1Materials..................................................................................................................... 37D2.2Equipment................................................................................................................... 37
D3Objectives........................................................................................................................... 37D4GeneralInstructions........................................................................................................... 38
D4.1FuelCellSystemConfiguration ...................................................................................38D4.2ExplanationoftheTestStation................................................................................... 38D4.3HardwareSpecifications.............................................................................................39D4.4DataFilingNamingConventions................................................................................. 39D4.6NomenclatureofTestConditionTemperatures......................................................... 39D4.7HandlingofGasTanks................................................................................................. 40
D5Day1Test........................................................................................................................... 40D5.1SetupCellHardwareontheTestStation.................................................................... 40D5.2PreparationofCellTestontheTestStation............................................................... 40D5.3OperationofComputertoStartUpCell .....................................................................40D5.4CrossoverandCyclicVoltammetryTestsat25/25/25...............................................42D5.5HumidificationoftheMembrane............................................................................... 44D5.6OperationoftheCellinBreakInMode...................................................................... 45D5.7
Cool
Down
Procedure.................................................................................................
45
D6Day2Test........................................................................................................................... 46
D6.1CrossoverandCyclicVoltammetryTestsat25/25/25...............................................46D6.2PolarizationCurveMeasurementat80/80/73(Air/O2Alternating)..........................46D6.3CrossoverandCyclicVoltammetryTestsat80/80/73...............................................48D6.4Holdat400mA/cm2Overnight.................................................................................. 49
D7Day3Test........................................................................................................................... 49D7.1PerformanceMeasurementat80/80/73(Air/O2Alternating,1.5atm).....................49
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D7.2PerformanceMeasurementat100/90/90(Air,1.5atm)...........................................49D7.3HoldOvernightat400mA/cm2..................................................................................49
D8Day4Test........................................................................................................................... 49D8.1PerformanceMeasurementat100/90/90(O2/AirAlternating,1.5atm)...................49D8.2CrossoverandCyclicVoltammetryTestsat120/90/90.............................................49D8.3PerformanceMeasurementat120/90/90(Air/O2Alternating,1.5atm)..................49D8.4HoldOvernightat400mA/cm2..................................................................................49
D9Day5Test........................................................................................................................... 49D9.1CrossoverandCyclicVoltammetryTestsat100/90/90.............................................49D9.2PerformanceMeasurementat100/90/90(Air/O2Alternating,1.5atm)...................49D9.3StabilityTest(Days5,6,and7).................................................................................... 50
D10Day8Test....................................................................................................................... 50D10.1CrossoverandCyclicVoltammetryTestsat100/90/90...........................................50D10.2PerformanceTestat100/90/90(Air/O2Alternating,1.5atm)................................. 50D10.3CoolDown................................................................................................................. 50
D11Day9Test......................................................................................................................... 51D11.1CrossoverandCyclicVoltammetryTestsat25/25/25.............................................51D11.2LeakTest................................................................................................................... 51D11.3ResistanceTest......................................................................................................... 51D11.4ShutDownandRemovefromTestStand................................................................. 51D11.5PostTestAnalysis..................................................................................................... 51
D15Troubleshooting:HardwareProblems.............................................................................51D16ChartSummarizingDaytoDayActivities......................................................................... 53
AppendixEFluorideConcentrationMeasurementsTestProcedure........................................... 54E1CheckingElectrodeOperation.......................................................................................... 54
E1.1SuggestedEquipment.................................................................................................. 54E1.2Procedure.................................................................................................................... 54
E2FluorideConcentrationMeasurements.............................................................................. 54E2.1DirectCalibration......................................................................................................... 54E2.2CalibrationCurve......................................................................................................... 55E2.3MeasuringSampleswithConcentrationsGreaterthan1ppm..................................56E2.4MeasuringSampleswithConcentrationsLessthan1ppm........................................57
E3ElectrodeCleaningandStorage.......................................................................................... 58E3.1ElectrodeCleaningI..................................................................................................... 58E3.2ElectrodeCleaningII .................................................................................................58E3.3
Electrode
Storage
I......................................................................................................
58
E3.4ElectrodeStorageII.....................................................................................................58
AppendixFSafetyPlan................................................................................................................. 59F1ScopeofWork..................................................................................................................... 60F2IdentificationofSafetyVulnerabilities................................................................................ 61F3RiskMitigationPlan............................................................................................................. 62
F3.1OrganicVaporExposure ..............................................................................................624
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F3.2CatalystHandling......................................................................................................... 62F3.3HydrogenLeaks........................................................................................................... 62F3.4StandardOperatingProcedures.................................................................................. 63F3.5PreviousExperienceWithHydrogen........................................................................... 64F3.6SafetyPerformanceMeasurementandManagementofChangeReviews................64F3.7EmployeeTraining....................................................................................................... 64F3.8EquipmentIntegrity..................................................................................................... 65F3.9MaintenanceofSafetyDocumentation......................................................................65
F4CommunicationPlan........................................................................................................... 66F4.1EmergencyResponsePlan........................................................................................... 66F4.2IncidentReportingandLessonsLearned....................................................................66
F5SampleHandlingandTransport.......................................................................................... 67F6References........................................................................................................................... 67
AppendixGFacilitiesandInstrumentation..................................................................................68G1MembraneFabrication........................................ 68G2MembraneElectrodeAssemblyFabrication...................................................68G3ElectrochemicalCharacterization.................................................................... 68G4MaterialsCharacterization..............................................................................68
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1.1 Introduction to the Test Protocol for PEM Cell TestsPEM singlecell testing for performance, durability and accelerated stress is conducted on aFeeforServicebasisatanumberofgovernmentaswellascommerciallaboratories. TheseservicesareavailablefortheindividualTask1teammemberswithcustomerspecificprotocolstomeettheirindividualtestingrequirements.ThisdocumentdefinesthePEMtestproceduresthatwillbeusedatFSECforconductingthescreeningteststhatarerequiredunderFSECsTask5CharacterizeperformanceofMEAoftheDOEprogramDEPS366095020. ThepurposeofthistestingistoassesstherelativemeritsofthecandidatemembranesthataresubmittedbytheTask1teammembers.ThesetestswillbeconductedatoperatingconditionsthatareofinteresttotheDOE. ThegoalistoshowthecurrentcapabilityofthesemembranesratherthansimplytoprovideaGo/NoGoratingagainsttheProgramRequirements. Afurtherobjectiveofthisprotocol istoclearlydefinetheoperatingconditionstowhichthe individualmembraneswill be subjected. This allows the details to be understood by the DOE; and, with thisinformation, each team member can set limits of processing and operation based on thecapabilities
of
their
individual
membranes.
To
the
extent
that
all
membranes
are
tested
to
the
same protocol, the results provide a fair and accurate evaluation of the performancecapabilities of each configuration. It is understood that the fabrication history for themembranes,aswellasthecharacteristicsoftheinterfacingcellcomponents,thecellassemblyprocedures, and the cell operating history can have a significant impact on the cellperformance.The impactofthesehistories isnormalized inthisprotocolbyusing identicalproceduresonallthecells.FSEChasfollowedthisprotocolonnumerouscellsandthistestprotocolproducedrepeatableresults.1.2ComponentstobeDeliveredTask 1 team members deliver sample membranes developed under this DOE program. Asufficientnumberofpiecessized12cmby12cm(4inchesby4inches)willbesubmittedtoenabletheteststobecompleted.Thesemembranes,alongwiththefabricatorsconstraintsforfurther processing, are represented to the DOE as the Task 1 team members best effort ofperformanceunderthisprogram.1.3DetailsoftheCellThetestCCM isfabricatedusingmembranesprovidedbytheTask1teammembers.PriortofabricationoftheCCM,membranesampleswillbeexaminedforuniformity(nobubbles,debris,fogginess, stretches, cracks, and thickness variations), gascrossover, and flexibilitytoensurethemembranesaresuitablefortesting. SamplepieceswillbecutfromthemembraneandsenttoBekktech,LLCandScribnerAssociatesforconductivitytestingandtoMaterialScienceattheUniversity of Central Florida for SEM/EDAX characterization. A diagram depicting how eachsuppliedmembranewillbeused isshown inFigure1.1.TheCCM is fabricatedbysprayingacatalystink(ionomer,Pt/C,methanolmixture)onamembranetoachieveanominalloadingof0.4mgPt/cm2 ofTEC10E50EPt50wt%catalystsupportedonahighsurfaceareacarbon(SA=800m2/g)suppliedbyTKK. FSEChasachievedbaselineperformancebymixingthecatalyst
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CCM
Conductivity 1
Conductivity 2
Coupon
Extra 12 cm
12cm
4 cm
5 cm 5 cm
4 cmcm
4 cm
8 cm
8 cm
with 32% 1100 EW Nafion using methanol and then spraying using a nitrogendriven spraygun,whichiscarriedbyanumericallycontrolledX/Zplotter.TheCCMisthendriedat100oC,heattreatedat136oCandcompressivelypressed5.1atm(75psi)compressivepressureforfiveminutes,andthenprotonatedusinga0.5Msulfuricacidsolutionandwashedindistilledwater.AsecondCCMandtwocouponsaremadeatthesametime,with identicalprocessing. ThissecondCCMandonecouponwillbereturnedtothemembranefabricatoruntestedfortheirevaluationandanalysis.FSECwillcommunicatewiththeteammembersaboutthefabricationconstraintsforeachmembraneandanattemptwillbemadetoaccommodatethemembranerequirementsandthesupplierwishes,whilestillachievingcomparableresults.Dependingonthemembranecompositionandthesupplierrequirements,itmaybenecessarytoadjustthetypeofionomer,ionomerloading,dryingtemperature,hotpresstemperatures,andsolvent.
CCM
Conductivity
#1
Conductivity
#2
Coupon
Extra 12 cm
4 cm
5 cm 5 cm
4 cm4 cm
4 cm
8 cm
8 cm
12cmFigure1.1.Depictionofmembranesamplepieces.CCMandcouponpieceswillbesprayedatthesametime.ConductivitypieceswillbesenttoScribnerandAssociatesandBekktechfortesting.The singlecell hardware (25 cm2) used for this program was manufactured by Fuel CellsTechnologies Incorporated (FCT) www.fuelcellstechnologies.com. It consists of a pair ofgraphitebipolarplateswithaserpentineflowpattern,goldcoatedcurrentcollectorplates,andaluminumpressureplates. Thedesignoftheanodebipolarplateflowfieldhasbeenrotated90togiveacrossflowpatternandthedimensionsoftheserpentineflowfieldforbothanodeand cathode have been modified (width and depth) to decrease pressure drop. All otheraspectsofthishardwareareasoriginallydesignedbyFCT.
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Figure1.2.Bipolarplates(anode,leftandcathode,right)showingsingleserpentineflowfield.All the MEAs for these cells use type 10BB gasdiffusion layers purchased from SGL Carbon(Sigracet)Eachofthesegasdiffusionlayersweretestedforthroughplanepermeabilitypriortouse,followingtheprocedure inAppendixA.Theminimumacceptablepermeabilityforthecathode GDL is given by a Gurley Number of 0.024 L/min/cm H2O/cm2. The anode GDLpermeability is allowed to be much lower. The cell seals are made of a stackup of Teflongaskets
with
the
thickness
of
the
gaskets
thinner
than
the
cell
assembly
giving
apinch
of
230
to250m (910mils).1.4Membrane,CCM,andGDLThicknessMeasurementThethicknessofthemembrane,CCM,andGDLsaremeasuredusingaMitutoyoGauge(Figure1.3).ComponentthicknessesaredefinedusingaverageofatleastninereadingsevaluatedovertheentirecomponentatlocationsshownonthetemplateinFigure1.4. Themembrane,CCM,or GDL is sandwiched between thin sheets of Teflon of known thickness when making themeasurements. Thetemplateisusedtomaintaintheconsistencyofthelocationofsuccessivemeasurements.TheTeflonsheetsaremeasuredfirstandthenthemembrane,CCM,orGDLisinsertedbetweenthemandasecondsetofreadingsistaken.Subtractingthefirstreadingfromthesecondprovidesthecomponentthickness.
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Figure1.3.MitutoyoGaugeformeasuringthicknessofmembranes,CCMs,MEAs,andGDLsX XX
XX X
X X X
MeasureeachMembranein9placesTaketheaverage
Figure1.4.Templateformeasuringthicknessofmembrane,CCM,GDL,andMEA1.5CellAssemblyFigure1.5showsanexpandedviewofacompletePEMfuelcellhardware. Thedesignofthehardwareisfor25cm2cells. Forthisprogram,cellsareassembledbyhandusingbipolarplates,load plates, and end plates purchased from FCT. Prior to assembly, GDLs are tested forpermeability, and cut to the required size. Teflon sheets are also die cut to size, and themembraneisspraycoatedwithamixtureofTKKplatinumoncarboncatalysttoformtheCCM.CCMshave0.4mg/cm2 catalystoneachelectrodeforthescreeningtests;howevertheycanbefabricated with catalyst loadings down to 0.05 mg/cm2 by the same processing equipment.After all components have been prepared, cleaned and documented, cells are assembled asdefinedintheAssemblyProcedure includedasAppendixB. Cellpinch,whichestablishesthecompressive loadontheactiveareaoftheMEA iscontrolledbyselectingTeflon sealinggasketsthatarethinnerthanthesumofthecomponentthicknessesintheactiveareaofthecell.Thispinch isacriticalparameterforcellassemblyand iscontrolledbyselectingTeflongasketsofappropriatethicknessasshowninFigure1.6.
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15 6515 65 15 85 15 6
15 95 15 7515 75 15 7515 95
15 6515 55
15 9515 6516 16 15
15 85 16 1 15 9
2 2
2 45
2 25
2 45
2 75
2 9
2 45 2 755
9 4
165
9 8
9 351 4
1
9 5
9 7
Figure1.5.ExpandedviewofPEMfuelcellhardware
1234
56
4321
7
5
1. EndPlate2. Goldcoatedcopperplate3. BipolarPlate4. TeflonGasket5. GasDiffusionLayer6. MEA7. M6Bolt
GDGDLL ThThiicckknneessss CCMCCMThThiicckknneessss398398 402 396
405 400400 400405
398395
405
398
406
400
402 409 404All numbers are in m.
Cathode
Anode
The gasketswere each 310m
566257
627074
62 7064
PiPinncchh239
254245249
237254
254
241
246Measure each componentin 9 placesBuildcellwith229254mpinchPinch= TGDL(Anode)+ TGDL(Cathode)+ TCCM TGaskets
Figure1.6.Schematicshowingsamplecalculationofpinchbymeasuringthicknessesofeachcomponentusingthetemplate.1.6Pre-TestIntegrityTestAfter the cell is built and before it is delivered to the test stand, it is externally leaktested,internally leaktested, and electrically isolationtested, each according to the procedures inAppendicesCandD. Thesetestsaretoensurethatthecellintegrityissufficienttowarrantthetesteffortandtoestablishapretestbaselinedatabase. Afterthecellismountedintheteststand,theexternalleaktestofthecellandthestand,andtheresistancetestsofthecelland
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thestandarerepeatedtovalidatetestreadiness. Allowable limitsforthesetestshavebeenestablishedbyacombinationofFSECscumulativetestexperienceandanimpactanalysisoftheworstcaselevelofleakageandcellresistanceoncellperformance. TheselevelswerealsoverifiedbythecurrentFSECdatabase.1.7TestsPerformedonEachCell1.7.1 Linear Sweep Voltammetry, Cyclic Voltammetry (CV), and Cell ConditioningPriortoperformanceevaluation,electrochemicalactivearea(ECA)andH2 crossover(CO)testsareperformedonthecellatambientpressureatroomtemperatureand100%RH,80oCand~100%RH,100oCand69%RH,and120oC and 35%RH.Thecathode istheworkingelectrodeandtheanode,usinghydrogen,isthecounteraswellasthereferenceelectrode. Flowsof0.4L/min of hydrogen and nitrogen are introduced to the anode and cathode side of the cell,respectively. The CV is conducted at a scan rate of 30 mV/s between zero and 0.8 V todetermine the ECA. Hydrogen crossover is measured by the limiting current density methodwith H2 flowing on the anode and nitrogen on the cathode. The cell potential is scannedpotentiodynamically at 4 mV/s from zero to 0.8 V. A PAR 263A potentiostat and CorrWaresoftware is used to control the potential. The crossover test shows both the level of gasdiffusionthroughthemembraneandanyelectricalshort.Thelevelofdiffusionisgivenbytheflatportionofthecurveandthelevelofshortiscalculatedfromtheslopinglinearrelationshipbetween the applied voltage and the measured current, specifically the measured currentbetween0.3Vand0.8V. Shortsmustbelessthantheequivalentof10mAtobeallowable,andtoclarifytheCVdata,thelinearslopesresultingfromtheseelectricalshortsareremovedfromthedata. Figure1.7showssampleCOdataandFigure1.8showssampleECAdataasafunction of cell temperature. In the CV data, the hydrogen desorption peaks can easily beobservedatroomtemperature.CVandCOtestswererepeatedbeforeeachtestconditiontoprovidedatainsupportofthecellanalysis.
i/mAcm-2
0.015
0.010
0.005
0.000
-0.005
-0.010
-0.015
Crossover
0.0 0.2 0.4 0.6 0.8 1.0
E / V
25/25/25 0.28 mA/cm2 (pretest)
80/80/73 0.76 mA/cm2
100/90/90 0.73 mA/cm2
120/90/90 1.98 mA/cm2
25/25/25 196 Ohm cm2 (post-test)
Indicativeofashort
Figure1.7.COdataatdifferentcelltemperatures.LinearsweepvoltammogramofFSEC1;scanrate=2mV/s,0.4L/min(H2/N2),Tcell=25,80,100,120oC,workingelectrode=cathode,counter/reference=anode.
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ECA
-0.02
-0.015
-0.01
-0.005
0
0.005
0.01
0 0.2 0.4 0.6 0.8 1
E / V
i/mAcm-2
25/25/25 39.3 m2/g
80/80/73 35.6 m2/g
100/90/90 22.3 m2/g
Figure1.8.ECAdataasafunctionofcelltemperature.CyclicVoltammogramofFSEC1;scanrate=30mV/s,0.4L/min(H2/N2),Tcell=25,80,100oC,workingelectrode=cathode,counter/reference=anode.Analysisofthecyclicvoltammogramprovidesameasureoftheelectrochemicalsurfacearea
(ECA)ofthecathode. PeriodicallyrepeatingthistestduringtheprogramprovidesahistoryofthechangesincathodeECAforsampleMEAsasafunctionofafixedtesthistory.Analysisofthesetestresultsshowscomparativemeritsofthesubmittedmembranes.It is recognized that the initial testing of CO/CV prior to conditioning the CCM does notrepresentthefullpotentialofthecell,butthesetestsprovideimportantdataabouttheinitialconditionofthecell.Inaddition,thisdataisrequiredasinputfortheanalysisofthecellduringoperation.AftertheCO/CVtest,thecell isheatedto80oCandthesaturatorsareheatedto80oC for the anode and 73 oC for the cathode, and the cell is conditioned for operation byaddingwatertotheelectrolyte. Thisisatwostepprocedure,wherewaterisfirstaddedasavaporfromsaturatedgases(hydrogenontheanodeandnitrogenonthecathode),andsecondbyoperationofthecellatafixedvoltageof0.55Vandrunonhydrogen/air. Eachstepisforthreehours,which,forNafion,hasproventobesufficienttowetuptheelectrolyte.After the electrolyte has been wetup, a series of performance curves are run at ambientpressureandhighstoichiometry. Thesetestsarerunatnear100%RHwiththecellat80oC.The air dew point is a few degrees lower than the cell temperature to avoid flooding thecathode.Performance sweeps are taken on H2/Air,H2/O2, andH2/Air out to ILim. or IMax. The limitingcurrent,ILim,isthecurrentwhenthecellvoltagebecomes0.3V.Thisvalueisusedratherthat0Vtoavoiddamagetothecell.Themaximumcurrent, IMax,isbasedontheteststandreactant
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flowcapabilityat2000mA/cm2.TherepeatoftheH2/Airsweepsallowsperformancebetweenthetwoteststobecomparedtoshowthatthecellhasreachedastablestartingperformancepoint,andtoindicatethatthedifferencesbetweentheairandtheoxygenperformanceisbeingmeasuredaccurately. Testpointsareheldforfiveminutesduringthistestingasacompromisebetweenfullystabledataandareasonableamountoftotaltesttime.Thecellisthenheldatthesesameconditions(80oC,80oC,73oC)whiletheinitialtestdataisreviewedandthecellintegrityisjudgedtobesufficienttoproceedwiththeremainderofthetesting. Ifthecellperformanceisnotadequate,itiscooledtoroomtemperature,theCO/CVisrepeatedandfurtherdataanalysisisconductedtodeterminethenextsteps.1.7.2 Performance Verif ication TestThe purpose of the Performance Verification Test is to provide data on cells operating at aseries of conditions that are at the DOE goals or that represent significant progress towardthose goals and show the relative merits of each of the candidate membranes at thoseconditions. Havingconditionedthecellandverifieditsintegrity,thePerformanceVerificationTestisstartedwithoutshuttingdown. Thecellispressurizedto1.5atmosphereswhileholdingthecelltemperatureandtheanodeandcathodesaturatortemperaturesat80oC,80oC,73oCrespectively; and a series of H2/Air, H2/O2, H2/Air performance sweeps are taken at highstoichiometry(above3tominimizetheeffectsofreactantutilization). Followingthesetests,thecellandsaturatorsareheatedto100oC,90oC,90oC,whichchangestheinletRHatthecellto69%.Thethreeperformancesweepsaretakenandthetemperaturesareincreasedagainto120 oC, 90 oC, 90 oC to further reduce the relative humidity to 35%. In all cases, the cell isreturnedto100 oC,90 oC,90 oC andheldat 400mA/cm2 overnighttoevaluate the stabilitybetween the different sets of lower relative humidity tests. Cell temperatures are held at100oC,90oC,90oCinpreparationforthestabilitytest.1.7.2.1 Polarization Curve
Figure1.9showstypicalperformancedata,whichshowsthreecharacteristicregions. Thefirst(lowcurrentdensityregion) isdominatedbyactivationoverpotential losses,thesecond(midcurrentdensity)isdominatedbyresistancelosses,andthethird(highcurrentdensityregion)isdominatedbymasstransportlosses. Analysisofthesecurves,andthechangestothevariousregionsofthecurves,asthetestingprogresses,provideskeyinsightsintotheperformanceandstabilityofthemembraneaswellasthecatalystlayerandthecatalystmembraneinterface.Fuel Utilization and air Utilization have significant impacts on the shape of these curves.Although
utilizations
used
are
higher
than
the
goal
values,
this
data
is
valuable
in
comparing
performancewithlowerfuelandairflows.ThehighestobtainablecurrentdensityisILim,whichisanimportantinputtotheanalysisoftheinternalresistanceofthecathode.
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FSEC1 CCM @ 120oC _1.5atm
Catalyst: TKK 45.5 Pt% 0.4mgPt/cm2
y = -0.0353Ln(x) + 1.0085
R2= 0.9985
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1 10 100 1000 10000
Current Density(mA/cm2)
CellVoltage
(V)
Air Vcell
Air_iR_Free
O2_iR_Free
Air_Cathod Resistance Corrected
O2_Cathode Resistance Corrected
Air_Ilim Correct
O2_Ilim Correct
Figure1.9. Typicalperformanceforaloadcalibrationsweep1.7.2.2 Stability Test
A64hourendurancetestisrunonthe25cm2 fuelcellunderH2/Air.Theoperatingconditionsare 400mA/cm2, 100 oC,1.5 atm,and 69% RH for both the H2 andairreactants. The cell ismaintainedataconstantcurrentwhilecellperformanceandresistancearemeasured. Initialandfinalelectrochemicalactivearea,fuelcrossover,andperformancearedeterminedatcelloperatingtemperature.Waterfromtheexitstreamsiscondensed,collected,andanalyzedforfluorideionconcentration.TypicalcellvoltageandcellresistancestabilitycurvesareshowninFigure1.10. Thevoltageandresistancearebothexpectedtobestablethroughoutthestabilitytest.AnychangeinperformanceorresistanceisaresultofMEAdegradationduetochemicalandmechanicalstress.
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Vta
V
0.9 250100/90/90
400 mA cm-1
0.8
Voltage
/V0.7
0.6
200
Resistanc
e
mOhmcm
2
1500.5
0.4100
0.3
Voltage0.2 500.0
0 20 40 60
Resistance
80
0
Time / h
0.1
Figure1.10.Typicalperformanceandcellresistancestabilitycurve.VoltageandresistanceofFSEC3,0.2L/min(H2/Air),Tcell= 90oC,%RH=30,i=400mA/cm2.1.7.3 Post-Test Integri ty TestAfterthecellistested,andbeforeitisremovedfromtheteststand,theexternalleaktestofthe cell and the stand, and the resistance tests of the cell and the stand are repeated toquantifytheendoftestcondition. Inaddition,beforethecellisdisassembled,it isexternallyleaktested,internallyleaktested,andelectricalisolationtestedonthebench,eachaccordingto the procedures in Appendices C and D. Bolt torque is also measured. These tests are todetermine the changes in the cell integrity as a result of the protocol testing. These testsprovidedataonsomeofthechangestothemembraneaswellasdataexternaltotheMEAthatisneededtosupportthecellanalysis.1.7.4 Post-test AnalysisFSEC has developed and verified a process to evaluate sources of polarization, mainlyassociated with the cathode, in hydrogen/air proton exchange membrane fuel cells and iscurrentlyusingthisprocesstoanalyzecellperformanceandguidedevelopmentefforts.Thisprocess quantifies the six sources of polarization using data from the standardized testprogram. Nonelectrode ohmic overpotential, electrode ohmic overpotential, nonelectrodeconcentration
overpotential,
electrode
concentration
overpotential,
activation
overpotential
from the Tafel slope, and activation overpotential from catalyst activity are analyticallyseparatedintotheirdistinctelements.Theanalysisisbasedonhydrogen/airpolarizationcurvesofaninhousemembraneelectrodeassembly(MEA)usinghydrogen/oxygenpolarizationcurvesas a diagnostic tool. The analysis results compare three cell temperature/relative humidity/oxygenpartialpressure(pO2,atm)conditions:80C/100%RHanode/75%RHcathode,100C/69%RH,and 120C/35% RH, which represent near fullyhumidified, moderately humidified, and lowhumidifiedconditions,respectively,at1.5atmoperatingpressure. Thetechniqueisusefulfor
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diagnosing the main sources of loss in MEA development work, especially for hightemperature/low relative humidity operation where several sources of loss are presentsimultaneously. Thefollowingverificationtestdataandanalysisisreported.1.7.5 Cell Data Report
The experimental testing of a new membrane will result in the following data to enable theevaluationofmembraneperformanceinacell: Cellbuildverificationtestdata
o Electronicresistanceforshortdeterminationo Externalleakagerateo Internalleakagerate
Cellcharacterizationatstartupo Cyclicvoltammetryat25oCtoenableelectrochemicalareadeterminationo Linear sweep voltammetry at 25 oC for crossover and electronic resistance
determination Performancetestdata
o Cellvoltageandcellresistance(OCVto0.3V)atthefollowingconditions: H2/O2andH2/Airreactantsat1.5atm,80oC/80oC/73oC(100%RH) H2/O2andH2/Airreactantsat1.5atm,100oC/90oC/90oC(69%RH) H2/O2andH2/Airreactantsat1.5atm,120oC/90oC/90oC(35%RH)
o AtabulationofcellcurrentdensityandresistanceusingH2/Airreactantsat0.7Vfor the above three conditions (This tabulation is provided to enable rapidmembranecomparisons.)
Stabilitytestdatao Cellvoltageandresistancefor100hoursatthefollowingconditions:
H2/Airreactantsat400mA/cm2,150kPa,100oC,69%RHo Cyclicvoltammetrytoenableposttestelectrochemicalareadeterminationo Linear sweep voltammetry for posttest crossover and electronic resistance
determinationo Fluoridepresentinexhaustcondensate
1.8FuelCellHydrogenSafetyPlanFlorida Solar Energy Center (FSEC) complies with the University of Central Florida (UCF)ChemicalHygienePlan(CHP),asrequiredbyOSHA. Thisplananditsassociateddocumentation(Safety Standards for Hydrogen and Hydrogen Systems SSHHS) provides a writtendescription
of
safety
policies
and
procedures
that
all
university
laboratory
personnel
must
follow. Allfacultyresearchers,studenttraineesandvisitingscientistsandengineersworkingatFSEC's hydrogen research laboratories are provided with training and a copy of SSHHSdocument. SSHHS document contains guidelines for hydrogen system design, materialselection, operation, storage, handling and transportation. Furthermore, FSEC's hydrogenlaboratoriesandfieldfacilitymeetand/orexceedthedesignandsafetyrequirementsimposedbytheFloridaStateFireMarshallandallthestateandfederalcodes(NFPA45StandardonFireProtection for Laboratories Using Chemicals, NFPA 50A Standard for Gaseous Hydrogen
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SystemsatConsumerSites,andNFPA70NationalElectricCode)forhandlinglargevolumesofhazardousandflammablegasesandchemicalsincludingbothgaseousandliquidhydrogen. Inaddition, FSECs hydrogen field facility has been upgraded with explosion proof electricalsystemsandmeetsNFPA50BCodeLiquefiedHydrogenSystemsatConsumerSites.Beforeeachnewresearchactivity is initiated,thepersonnelsafetyatandnearthe facility isreviewedandemergencyproceduresimplementedattheearliestplanninganddesignstages.Advanceplanningforavarietyofemergenciessuchasfiresandexplosionsareconductedandproper procedures developed and implemented. All hydrogen systems will be instrumentedandcheckedfor:
i. Processmonitoringandcontrol.ii. Collectionofperformancedata.iii. Providingwarningsand/oralarmsforoutoflimitsconditions.iv. Earlydetectionofhazardouscondition(s).v. Compatibilitywithhydrogenservice.vi. Establishmentoflocaland/orremoteoperationandmonitoringofthehydrogensystem.vii. Havingappropriaterange,accuracy,andresponsetime.
The SafetyAssessmentReviewshallbeupdatedanytimeasystemorprocess ischanged.Anannualfacilityinspectionshallbeconductedanddocumented.AformalOperatingandSupportHazardAnalysis shall be performedas directed by the UCFEnvironmental Health and SafetyOffice.Significanthazardsidentifiedshallbeeliminatedorreducedtoacceptablerisklevels.Mr.RandyFowler istheFSEC'sHydrogenR&DLaboratories'operationalandsafetymanager.Hehasattendedandcompletedthefollowingsafetyrelatedcoursesandtrainingactivities:
i. A full day course on HazMat and received his certification on spill control andrespirators.
ii. HassuccessfullycompletedNASAHydrogenSafetyclass.iii. AttendedtheLabSafetyBasicsandBeyondatPITTCON.iv. Taken and passed UCF's Chemical Safety and Environmental Management for
Laboratoriesclass.v. HaspostsecondaryvocationalcertificategivenbytheBrevardCommunityCollegeon
ChemicalLaboratorySpecialist,Decemberof2002.Mr.
Fowler
oversees
the
enforcement
of
all
hydrogen
and
chemical
safety
procedures
and
trainingofthegraduateresearchstudentsworkinginFSEC'shydrogenlaboratories. Inaddition,acomprehensivesafetyplanwillbedevelopedandsubmittedtoDOEatthetimeofcontractaward. Inpreparationforthisplan,thefollowingstepswillalsobetaken:
TheChemicalHygienePlan(CHP)willbereevaluated,modifiedasneededandperiodicallycheckedforcompliance.
Astandardoperatingprocedure(SOP)willbeestablishedforallexperimentsandoperationstakingintoaccounthazardlevelofmaterialstobeused.
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ProcedureswillbedevelopedforreportinganyeventsordeviationsfromSOP. Failureriskmitigationplanwillbedevelopedbasedonvulnerabilitiesidentified
byModesandEffectsAnalysis.
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2.DaybyDayPEMMEATestSequence2.1AssembletheCell TheSampleMEA
- Fromteammemberstwopieces12cmx12cm(4.75x4.75) AnodeandCathodeCatalyst
- TKK46%Ptcatalyst- 0.4mg/cm2- 32wt%Nafion1100binder- Spray- 136
oCheattreat
- Protonation- Twoidentical:Onetested/Onereturneduntested
GDL- SGL10BB Pinch0.25mm+/0.02mm(0.01+/0.001)
TeflonGasketLayup FCTCell
- HardwareSinglepassserpentine- Crossflowcathodehorizontal- FSECbarandgroovedimensions
BoltLoad- Starpattern- 4.5Nmtorque(40inchpounds)
PretestConductivity
TestedatBekkTech
2.2Day1 Measuremechanicalcrossover
- 100Ohms- AnodetoCathode>30Ohms
Mountinteststand- ResistanceAnode/Cathodetoground>100Ohmsacceptable
RoomtemperatureCOandCV WetUp
- 80/80/73 H2/N23hNoLoad H2/Air~3h0.55V
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Cooldowntoroomtemperature- HoldonN2/N2
2.3Day2 RoomtemperatureCOandCV Heatup
- H2/N2- 80/80/73oC- Ambientpressure
Measure- Opencircuitvoltage(OCV),- Performance(voltsvs.current)curve(VI)- Cellresistance(bycurrentinterrupt)
StoichiometryAnode3,Cathode3.6
H2/Air H2/O2 H2/Air COandCVat80/80/73oC Holdovernightat400mA/cm22.4Day3 Pressurizeto1.5atm Measureat80/80/73oC
- OCV,VIcurve,cellresistance Stoichiometry
Anode3,Cathode3.6 H2/Air H2/O2 H2/Air Heatto100/90/90oC COandCVat100/90/90oC Measure
- OCV,VIcurve,cellresistance Stoichiometry
Anode3,Cathode3.6
H2/Air
Holdovernightat400mA/cm22.5Day4(at1.5atm) RunVIcurveat100/90/90oC
- Stoichiometry Anode3,Cathode3.6
- H2/Air
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- H2/ O2- H2/Air
Heatto120/90/90oC RecordCOandCVat120/90/90oC Measure
- OCV,VIcurve,cellresistance Stoichiometry
Anode3,Cathode3.6 H2/Air H2/O2 H2/Air Coolto100/90/90oC Holdovernightat400mA/cm22.6Day5,6,7(at1.5atm)StabilityTest RecordCOandCVat100/90/90oC Measure
- OCV,VIcurve,cellresistance Stoichiometry
Anode3,Cathode3.6 H2/Air H2/O2 H2/Air Startstabilitytest
- 1.5atm- 100/90/90oC- H2/Air- 400mA/cm2
Stoichiometry- Anode3,Cathode3.6
Measureduringstabilitytest Cellvoltage Fluorideemissionrate(FER)inreactantexhausts
2.7Day8(at1.5atm) RecordCOandCVat100/90/90oC Measure
- OCV,VIcurve,cellresistance Stoichiometry
Anode3,Cathode3.6 H2/Air H2/O2 H2/Air
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Cooldowntoroomtemperature H2/N22.8Day9 RoomtemperatureCOandCV Resistancetest
- Anodetoground- Cathodetoground
Removethecell Measuremechanicalcrossover
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Appendix A: Gurley Number TestProcedures
DocumentNumberWP0012WPQRSA1.ReferencematerialsA1.1MinKyuSong,PEMFCUnitCellAssemblyforNTMembraneandETEKElectrode,March13,2001,UconnA1.2B.Mueller,E.DeCastroetc.,CARBONCLOTHGASDIFFUSIONBACKINGSFORHIGHPERFORMANCEPEFCCATHODES,ElectrochemicalSocietyProceedingsVolume9827A2.IntroductionFor porous and/or fibrous gas filtration media, resistance to flow is often used as acharacteristicmeasureforqualitycontrolandperformance.GurleyNumberbasicallymeasuresgaspermeationratethroughthegasdiffusionbackingsamples.TheGurleynumberrepresentsthegasflowrate(inLPM)foraGasDiffusionLayersampleatafixedpressuredifference(incmofH2O)throughafixedareaofsample(cm2),andthusindicatestheresistancetogasflow.Samplesofgasdiffusion layerswerecutandfitted intoamanifoldofmaingasketsandsubgaskets,suchthattheuncoatedsideofthebackingisorientedtowardsthenitrogeninletandthatthereisnopinchontheGasDiffusionLayer.Thetotalgasketthicknesshasconsiderableinfluence on the pressure distribution pattern over the active area on both inlet and outletsides. Therefore, it is very important to employ enough thickness gaskets to get relativelyuniformpressuredistribution,resultinginmoremeaningfulGurleynumbers.Priortoevaluationofabackingsample,thesysteminherentresistancetogasflowisevaluatedbymeasuringpressuredropacrossthecelloverarangeofflowrates.Thissystemresistancetoflowisusedasacorrectioninthesubsequentmeasurementofbackinggasflowcharacteristics.TheconfigurationofthesystemisillustratedasinFigureA1.
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FlowMeterDigital
NeedleMeterCell
ValveAssembly
SlantPressureGuage
FigureA1.ApparatusforMeasuringGurleyNumberA3.MaterialsandEquipmentA3.1 Materials
Teflonfilm(0.25mm(10mil)thickness) Krytox(Dupontperformancelubricants,TeflonGrease) GasDiffusionLayers SnoopLiquidLeakDetector Ethyl Alcohol 200 Proof, Absolute (Dehydrated) USP Grade, Pharmco Products
INC DeionizedWater(From153FuelCellsLaboratoryERI)
A3.2 Equipment
ElectronicDigitalMicrometer(Mitutoyo) CARVERHydraulicPress(UnitModel#3912) ClickerDies TorqueWrench(05.6Nm,0to50inlbs) 3/8inchNutDriver NutPlate
Tweezers
Knife SingleCellParts
GraphiteFlowChannelGoldPlatedCopperPlatesInsulatorSleevesM6Bolts/M6NutsFlatWashers
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A3.3. Quality control (test and cri ter ia)
QS0012GasPermeability,GasDiffusionLayer.
A4.MainGasketPreparationTo ensure sealingoverthegasdiffusion layeredges, themaingasketthickness should beatleast51m(2mil)thinnerthanthegasdiffusionlayerthickness.Ingeneral,thecarbonpapersandcarbonclothsfallintherangebetween356and457m(14and18mil).Inthiscase,a254m(10mil)thickTeflonmaingasketwouldbeappropriate.However,itisimportanttokeepinmindthatweshouldalwaysusealittlethinnermaingasketthangasdiffusionlayers.Usingclickerdieandhydraulicpress,makeanormalsizegasket,thenmake it6.5mm(1/4)largeroneachside.Usinga25cm2cellasanexample,anormalgasketwouldbelikeinFigA2a.Aftermadelarger,thegasketwouldlooklikeinFigA2b.
OriginalGasket EnlargedGasket
Outsidedimension:9.5x9.5cm2Insidedimension:5.2x5.2cm2 Outsidedimension:9.5x9.5cm
2Insidedimension:6.5x6.5cm2
a bFigureA2.PreparationofMainGaskets(5.25.2cm2cellsize)A5.PreparationofSub-gasketsSubgasketsaredesignedwitha5.8cmx5.8cminsidedimensionandtheoutsidedimensionisthesameasfornormalgaskets.However,itisveryimportanttoprepareenoughthickgasketstoguaranteethatwecanhaveauniformpressuredistributionontheactivearea,whichwillleadtoameaningfulGurleyNumber.Thecorrecttotalthicknessdependsontheactivearea,andonthephysicalpropertiesofgasdiffusionlayers.It isalso importanttoalternatethinandthickgaskets inthefinalassemblytoensurepropersealingbythegaskets.
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From experience, for 5 cm2, 6.25 cm2, and 25 cm2 cells, 3810m (150 mil) of total gasketthicknessisenoughtogenerateauniformpressuredistribution.Supposethethicknessofthemaingasketis254m(10mil).Wecoulduseseven254m(10mil)gaskets,thenone254m(10mil)maingasket.Thetotalgasketthicknesswouldbe1778+1778+254=3810m(70+70+10=150mil).A6.PreparationofGasDiffusionLayersamplesGasDiffusionLayersshouldbestrictlycutaccordingtothesizeofthemaingasket(FigureA2b,6.5x6.5cm).Toensurepropersealingontheedgesofthegasdiffusionlayer,itisimportanttomakesurethatthesampleandthemaingasketmatchesnicely.A7.CleaningofFuelCellComponents
i. Rinsethegoldplatedcopperplate,graphiteflowchannelblockandTeflongasketswithdeionizedwaterbysoftbrushing.
ii. Washthemwithethanol.iii. Drythematroomtemperature.
A8.AssemblyProcedureNote.AllpartsshouldbeorientedasshowninFigureA3.
i. LubricatethesurfaceofthreadofM6BoltsusingKrytoxTeflongrease.Note.VerifynutsturnfreelyonM6boltsbeforeplacingboltinthenutplate.
ii. PlaceM6boltsheaddownintheNutPlate.iii. PutflatwashersonthroughtheNuts.iv. PlaceInsulationSleevesonthroughtheNuts.v. PlaceGoldPlatedCopperAlloyPlateon.vi.
Put
Bipolar
Plate
on.
vii. Put1778m(70mil)Teflonsubgasketon(7layers,254mor10milforeach).
Note.Alignnotchesineachgasket.viii.Putthemaingasket(254mor10milthick)onandalignsubgasketsandmain
gasket.ix. Putthegasdiffusionlayeronthemaingasket.Makesuretheyfitnicelyandthe
coatedsidefacesup.x. Putanother254m(70mil)Teflonsubgasketontop(7layers,254mor10milfor
each).Note.Alignnotcheswithfirstsevengasketlayers(step7).
xi. Puttheotherbipolarplateon.xii. Puttheothergoldplatedcopperalloyplateon.xiii.Putinsulationsleevesin.xiv. Putflatwasherson.xv. PlaceNutson.TightennutsusingaTorqueWrenchandNutDriverinthesequence1
to8asshowninFigureA4.Apply2.8Nm(25inlb)torqueforeachbolt.Note.Nutsmustturnfreelybyhandbeforeapplyingtorque.
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Note.Besuretoputthecellontothenutplatetotightennuts.Afterthat,itcanbehardtotakethecelloff. Inthiscase,putascrewdriverbetweenthecellandthenutsplateandgentlymove thescrewdriverupward (onboth sides),the cell willbeeasily takenoutofthe nutplate.Also,usenutplatetoloosenthenuts.
xvi.ConnectgastubesasinFigureA3.
ToSlantGauge N2Low Pressure OutEnd
N2In ToSlantGaugeHigh
PressureEndFigureA3.CellConnectionsinGurleyTest
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1
23
45
67
8
M6Bolt
GoldPlatedCopperPlate
BipolarPlate
GasDiffusionLayerand MainGasket
Teflon
SubGaskets
M6Nuts
Teflon
SubGasket
GoldPlatedCopperPlate
BipolarPlate
NutPlate
FigureA4.CellAssemblyExplosionViewinGurleyTest
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A9.LeakingCheckProcedureEveryconnectionshown inFigureA3shouldbe leaktestedbeforetakingmeasurements.Forthecell itself,thegasketsideshouldbetestedtomakesurethere isno leak inbetweenthegaskets.Theleaktestprocedureisasfollows:
i. Verifythatthepressuredropmeterisinhorizontalposition(thatshouldbecheckedusingalevel),andtheslantliquidlevelisat0positionwithnopressureapplied.
Note.Verifyneedlevalveisclosed.ii. OpenN2gas,keeppressure~0.68atm (10psi).iii. Adjustpressuredropat0.05inchH2O.Openvalveslowly,makesurethatpressure
dropcanbeheldat0.05inchslantliquidexactly.iv. HoldSnooptubeendatconnectionandsqueezeuprightbottletoapplysolidstream
ofSnoopliquidleakdetector.Bubblesformifconnectionleaks.Bubblesizeindicatesapproximateleaksize.
Note.Fordifferentsizegasketsanddifferentgasdiffusionlayers,pressuredropacrossthecellmayvarytremendouslywhenmeasuringGurleyNumber.Sincepressuresdropandflowratehaveanearlylinearrelationship,ingeneral,pressuredropcanbeusedasacontrolfactortotakeflowratemeasurements.v. FillreservoirwithSnoopLeakdetectorSolutionifitisnotenough.vi. TurnOnDigitalFlowmeter,pressballgently,andmakesurethatonesinglebubbleis
generatedatonetime.vii. Repeatuntiltheflowrateisrelativelyconstant(0.03L/min.),andthesurfaceof
flowmeteriswetenough.Recordtheflowrateresultontheform(below).viii. Adjustpressuredropat0.1,0.15and0.2inchH2O,repeatsteps(12).
A10.Dataprocessi.CalculateGurleyNumberwiththeaverageofflowratewithequation1.
FlowRate(LPM )GurleyNumber = . (1)
Pr essureDrop * 2.54 *ActiveArea
ActiveAreaistheareaofsubgasketopeningarea,for25cm2cellis5.85.8cm2.ii.CalculateAverageGurleyNumber(GN), ifthePercentRelativeStandardDeviation(%
RSD)ofGurleyNumber>10%,atallpressuredrop,needREDOit. (x xi )2
n 1RSD = 100% , (2)
x
wherex GNaverage,ximeasuredGNatadjustpressuredropat0.05,0.1,0.15and0.2inchH2O.
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A10.1 Data sheet Gurley number calculations:Samplenumber:GDLDate:
Pressure DropLPM 0.05 0.1 0.15 0.2
LPM1LPM2LPM3LPM4LPM5Avr.LPM GNAverage
GurleyNumber(GN)RSD %
RSDAccept 10%GDLAccept 0.100.18GDLReject 0.18A11.AcceptanceInspectinaccordancewithQS0012GasPermeability,GasDiffusionLayer.
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Appendix B: PEM Fuel Cell Unit CellAssembly Procedure
25 cm2DocumentNumberWPxyzB1ReferencematerialsJ.C.Lin,PreparationandCharacterizationofCompositeProtonExchangeMembranesforFuelCellApplication,Ph.D.Thesis,UConn(2000).B2BillofMaterialsB2.1 Materials
i. Acatalystcoatedmembrane(CCM)consistingof Apieceofmembrane(eitherFSEC1,FSEC3,NRE211,NRE212,Nafion112,etc.) Acathodecatalystlayerononeside(~0.4mg/cm2),activeareaof25cm2. Ananodecatalystsprayedontotheotherside(~0.4mg/cm2),activeareaof25cm2.
ii. Onepieceofgasdiffusionlayer,5.8x5.8cm2,withGurleynumberofatleast0.024L/min/cmH2O/cm
2forCATHODEGDL
iii. Onepieceofgasdiffusionlayer,5.8x5.8cm2,withGurleynumberofatleast0.01L/min/cmH2O/cm
2forANODEGDL
iv. Teflonfilm(25.4m(1mil)thickness)v. Krytox(Dupontperformancelubricants,TeflonGrease)vi.
Deionized
Water
and
ethanol
for
washing
B2.2 Equipment
i. AsinglecellhardwaresetAFuelCellTechnology(FCT)hardwaresetconsistsof: Twouniquelymachinedgraphiteflowfields(withFSEClowdeltaPserpentine
grooves) Twoaluminumendplates1.27cm()thickness Twogoldplatedcurrentcollectors0.32cm(1/8)thickness Fourplasticrubbertubes0.95cm(3/8)long,0.2mmindiameter(calledlineup
pins) Fourblackrubberorings(tosealallthelineuppins) EightStainlessscrews Eightblackrubberinsulatingsocks(oneforeachscrew)
ii. DigitalBalance(METTLERAE240,S/NG56273)iii. ElectronicDigitalMicrometer(Mitutoyo)iv. TorqueWrench(0to5.6Nmor0to50inlbs)
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B3Objectives:TodescribehowtoassembleaPEMfuelcellunitcell(calledMembraneElectrodeAssembly,MEA)usingaNafionbasedmembraneandSGL10BBGDLs.
B4General
Instructions
Lubricatetheboltseverytwocellstomakecertaintherightamountoftorqueisappliedto
thecell(notthefrictionforce) Alignment of all components vertically is VERY CRITICAL. Take care to ensure good
alignment(even if itmeansSTARTINGOVER, ifyoufeelunsure). MisalignmentwillcausethecelltofailandwastealltheeffortoftheCCMpreparation.
B5PreparationforCellAssemblyi. Checkthatthehardwaresetcontainsalltheparts.Separatethecathodepartsand
anodepartsaslabeled.ii. Clean the surface of the two graphite flow fields with ethanol. Take care not to
leaveexcessethanolinflowfieldspriortoassembly.iii. MeasurethethicknessoftheCCMbyplacingitbetweentwo1milTeflon films(for
surfaceprotection)andmeasuretheoverallthicknesswithaMitutoyocaliper.ThensubtractofftheTeflon filmthickness.MeasureATLEAST9VALUESandobtainanaveragevalue.
iv. RepeatStepiiiforcathodeGDLandanodeGDL.v. Setthedesiredamountofpinchinthiscase,229254m(910mils)vi. CalculatethetotalthicknessofneededTeflongasketsby:
Totalthicknessofthegaskets=(Tccm+TGDL,C,+TGDL,A)PinchTotalthicknessofeachside(CathodeandAnode)=Totalthicknessofthegaskets/2
Note 1. If the total thickness of the gaskets is an ODD number, make total cathode gasketthicknessLESSthantotalanodegasketthickness.Note2.Usually(Tccm+TGDL,C,+TGDL,A)isintheorderof762889m(3035mils)
vii. PreparedifferentcombinationsofTeflongaskets(availableas25,51,76,127,and254mor1,2,3,5and10mil)forthecathodeandanodesides.
Note.Cuteachgasketusinganappropriatelydesigneddiespecifictoeachhardwaredesign.viii. CutbothGDLstothesizethatwillfitPERFECTLY(within0.3mm)insidethemiddle
openingofthepreparedgaskets.Theopening isslightlybigger(12mm)thanthecellactivearea).
B6Assembling
the
Cell
Fuel
Cell
Technology
(FCT)
hardware
set
RefertoFigureB1.
i. Placefourboltsthroughthecathodeendplateforalignmentofcellparts.ii. Placethecathodeendplatewithboltsatthebottomonasturdysurface.iii. Placethecathodegoldplatedcurrentcollectorplateontopofthecathodeend
plate.iv. Placethetwolineuptubesandtwooringsintolineupholesofthecathodeend
platetoaligntheendplatewiththecathodegoldplatedcurrentcollector.32
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v. Placethecathodegraphiteflowfieldontopofthecathodegoldplatedcurrentcollector(withthegroovedsideup).
vi. Placethesetofcathodegasketsontop.MakeSUREitalignswellwithalltheboltholes.Usea1cmlongpieceofscotchtapetoattachthegasketstotheflowfieldplatetoensurealignmentinthecell,IFNECESSARY.
vii. PlacethecathodeGDLinthemiddleofthesetofgaskets(microporouslayersideUP).
viii. PlacetheCCMontop(ANODEsideUP);alignthecatalystactiveareainthemiddleofthegasketmiddleopening.
ix. Placethesetofanodegasketsontop.MakeSUREitalignswellwithallthebolt/nutholes.
x. PlacetheanodeGDLontop,alignitwiththeanodeGDL(microporouslayersideDOWN).
xi. Placetheanodeflowfieldplateontop(groovesideDOWN).xii. Placetheanodegoldplatedcurrentcollectorplateontop.xiii. Placetheanodeendplateontop(withthetwoplasticlineuptubesandoringsin
place.xiv. Tightenalltheboltsinacrosswiseorstarpattern.Insixcycles:
A. Tightenlooselybyhand(avoidovertighteningandapplyingtoomuchtorque)B. Tightenwithatorquewrench,setto1.1Nm(10inlbs),byfeelingtheclickC. Tightenwithatorquewrench,setto2.3Nm(20inlbs),byfeelingtheclickD. Tightenwithatorquewrench,setto3.4Nm(30inlbs),byfeelingtheclickE. Tightenwithatorquewrench,setto4.5Nm(40inlbs),byfeelingtheclickF. Recheckallboltswiththetorquewrenchsetat4.5Nm(40inlbs),byfeelingthe
clickxv. Theassembledcellisnowreadyforasinglecellperformancetest.
1234
56
4321
7
5
1. EndPlate2. Goldcoatedcopperplate3. BipolarPlate4. TeflonGasket5. GasDiffusionLayer6. MEA7. M6Bolt
FigureB1.Expandedviewofassembledfuelcell
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Appendix C: Procedure for Leak Testing aSingle Cell after Assembly
DocumentNo.WP0023andWP0024C1ExternalLeakTestC1.1 Procedure
i. SetupperFigureC1ii. ConnectN2tohydrogensidewithaflowmeterfollowedbyanisolationvalve.iii. Connectgasoutlinetohydrogenside,withaninlettotheair/O2sideiv. Connectgasoutlinetoair/O2sidewitha0to0.39atm(0to300mmHg)pressure
gaugefollowedbyanisolationvalve.v. Pressurizethehydrogenandair/oxygensidesto0.03,0.07,0.14,0.2atm(0.5,1,2,
3psi)withnitrogen,respectively.vi. Recorddataoftheflowmeter.vii. LeakcheckwithDIwater,writedownwherethebubblescomefrom.Canuse
Snooponplumbingconnection,notoncell.viii. Ifnoleakcanbeobservedandflowmeterremainsatzero,closethevalve,record
pressuredropin5min.0300mmHg
SingleCell
N2Supply
Valve
VentP Valve
Flowmeter
FigureC1. SetupforExternalLeakTest
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C2InternalLeakTestC2.1 Procedure for Internal Leak
i. Verifythatexternalcellleakagesatisfiestherequirementsii. SetupFigureC2iii. ConnectN2inlettothehydrogenside,withaflowmeterfollowedbyanisolation
valveiv. Connectgasoutlettothehydrogensidewitha00.39atm(0300mmHg)pressure
gaugefollowedbyanisolationvalvev. Connectbubblemetertoairsidevi. Closethehydrogenventandpressurizethehydrogensideto0.03,0.07,0.14,0.2
atm(0.5,1,2,3psig)withN2,respectivelyvii. Checktheflowrateattheair/oxygenventwiththebubbleflowmeterandflow
meter,recorddataondatasheetviii. Ifnoleakcanbefoundandflowmeterremainsatzero,closethevalveandrecord
pressuredropin5min.C2.2 Procedure for Internal Leak
i. SetupFigureC2ii. ConnectN2inlettotheair/oxygenside,withaflowmeterfollowedbyanisolation
valveiii. Connectgasoutlettoair/oxygenside,witha00.39atm(0300mmHg)pressure
gaugefollowedbyanisolationvalve,otheroutletshouldbeclosediv. Connectbubblemetertohydrogensidev. Closetheair/oxygenventandpressurizethehydrogensideto0.03,0.07,0.14,0.2
atm(0.5,1,2,3psig)withN2,respectivelyvi. Checktheflowrateatthehydrogenventwiththebubbleflowmeterandflow
meter,recorddataondatasheetvii. Ifnoleakcanbefoundandflowmeterremainsatzero,closethevalveandrecord
pressuredropin5min.
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SingleCellAssemblyValve
VentN2Supply Bubble
MeterFlowmeter
Singlecell
0 300mmHg
ValveVent
P
FigureC2: SetupforInternalLeakTest
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Appendix D: PEMFC Unit Cell Test
D1.Referencematerialsi.
FuelCell
Test
System
Configuration,
Scribner
Associates,
Inc.
ii. FuelCellforWindows:FuelCellTestSoftware,ScribnerAssociate,Inc.iii. Operating Manual of Fuel Cell for Windows, Fuel cell Test Software, Scribner
Associatesmodel890loadsystems,Version2.0iv. ScribnerAssociatesInc. 850CFuelCellTestSystemOperatingManualv. ConfigurationandApplicationManualofFuelcellTestSystemConfigurationvi. OperatingManualofCorrWareforWindows,Electrochemistry/Corrosion Software,
ScribnerAssociatesInc.,Version2.2vii. The Princeton Applied Research Potentiostat/Galvanostat Model 263A Operating
ManualD2.BillofMaterialsD2.1 Materials
D2.1.1Gasesi.Nitrogen Ultrahighpurity(99.999%),AirgasN.E.ii.Oxygen ZeroGrade(99.8%),AirgasN.E.iii.Air ZeroGrade(90%),Compressed,AirgasN.E.iv.Hydrogen Ultrahighpurity(99.999%),AirgasN.E.
D2.1.2Deionizedwater FacilityDIwaterD2.2 Equipment
i.FuelCellTestStationii.FuelCellTestLoadBoxiii.ScribnerSeries890Bor850CElectronicLoadandDataAcquisitionSystemiv.ScribnerModel871ReformateSimulator(optionalnotactive)v.IBMPCwithNationalInstrumentsGPIPPCIInterfaceandGPIBCablevi.CellCableSetsvii.Potentiostat/GalvanostatModel263,PrincetonAppliedResearchviii.Insulationjacket(Cloth)ix.Aplasticjackx.Wrench(13mm)xi. Multimeter, OMEGA, HHM25 KIT, OMEGA ENGINEERING INC. STAMFORD CT,
U.S.A.xii.Plasticbottlefordeionizedwater
D3ObjectivesTodescribetheperformancetestprocedureofaPEMfuelcell.
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Theoverallobjectiveofthistestsequenceistodeterminetheperformancecharacteristicsofasingle,benchscale,protonexchangemembranefuelcelloverarangeoftemperaturesfrom80oCto120oC.Thecellactiveareais25cm2.D4GeneralInstructionsBeforethecellismountedintheteststand,areviewshouldbeperformedoftheproceduresdescribed below and a check made of the availability of all of the materials and facilities toperformthetestprogram.D4.1 Fuel Cell System Configuration
OCathode
AirOutletAnodeOutlet
N
TestStationH2ReformateFigure D1. Schematic of Fuel Cell System Configuration
D4.2 Explanation of the test station
Gasesflowthroughmassflowcontrollerandhumidifiertothefuelcell. GasflowrateiscontrolledbyMKS1179Amassflowcontrollers
Gastemperatureandhumidityareadjustedbyspargingthegasesthroughstainlesssteelhumidifiertanks.
5
5
5
5
5
3wayvalve
So enoi valve Massflowcontroller
Bypass
Condenser
Condenser
Humidifier
Humidifier
Backpressureregulator
Vent
LoadIBM
FuelCellSolenoidvalve
Solenoidvalve
Massflowcontroller
Checkvalve
Checkvalve
Heater
Heater
Vent
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Thehumidifiedgasesareintroducedtothefuelcellhardware. Thegasesdiffusetotheelectrodesthroughgasdiffusionlayerwhiletheyarecirculating
alongthegaschannel. Theexhaustedgasespassthroughthebackpressureregulatorandthentothevent.
D4.3 Hardware SpecificationsD4.3.1ElectronicLoadSystem:
LoadCurrentRange 10,25,100A, fullscaleLoadVoltage 20Vmax.LoadPowerRange 100WMinLoadResistance 0.5to1mIRMeasurement CurrentInterruptmethodCurrentMeasurement HallEffectDeviceLoadCooling Forcedair,oneorthreefans
D4.3.2 PowerRequirementsandPhysicalMain Power 90 125 V AC, 50 60 Hz, 4 ALoadandDataUnit 17W10H21D(432553mm)Weight 3550lbs(1623kg)SystemInterfaceBox 8W3H10D
D4.4 Data File Name ConventionThedatafilenamingconventionisBxxxDyyRzzAA,where BstandsforBUILD xxxrepresentsthe cell numberthat is assigned by the database upon entry ofthe cell
assemblyrecordinformation DstandsforDAY yyrepresentsthenumberofdaysthatthecellhasbeentested
(Donotcountdayselapsed,onlythedaysthatthecellhasbeenoperated:thefirstdaythatyouoperatethecellYY=1,ifyouoperatethecellthenextday,oranynumberofdayslater,thenYY=2,thethirddaythecellisoperated,YY=3,andsoon.)
RstandsforRUN zzrepresentsthenumberoftherunduringday AArepresentthetypeofdatacollectedUsepropernomenclatureasfollows:
COstandsforcrossover(toestimatehydrogencrossover) CVstandsforcyclicvoltammetry(toestimateECAelectrochemicalsurfacearea) VIstandsforvoltagecurrent(performanceorpolarizationcurve) CCstandsforconstantcurrent(constantcurrentoperation)
D4.6 Nomenclature of the test condition (temperatures) is B/C/D :
BreferstoTcellinoC Creferstoanodehumidifiercontrollertemperatures(bothtopandbottom)inoC Dreferstocathodehumidifiercontrollertemperatures(bothtopandbottom)inoC
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Whenusercontrolsgaslines,theyarealways10oChigherthanTcell.D4.7 Handling of gas tanks
At the beginning of EACH day, verify that all gas (N2, H2, Air, and O2) cylinders haveenoughpressure(Above13atmor200psi).
AtthebeginningofDay1,OPENgastanksforN2,H2,andAir(allgasesusedthatday).Seteachgasregulatorat3.4atm(50psi).
D5Day1TestD5.1 Setup Cell Hardware on the Test StationTimerequiredforthisstep:~30minutes
i. Use a multimeter to measure the resistance between two graphite plates (anode andcathode).Waituntilthevalueisstabilizedandrecordtheexactvalue.
Note.Thisstep istoseethattheresistancevalue ishighenough(~50ohm)thatthere isnoindicationofshort.Iftheresistanceislowerthan10ohm,rebuildthecell.
ii. ConnectfourgastubestothefuelcellhardwareNote1.MakesurethatanodeandcathodeplatescorrespondtothoseoftheMEAinside.Note2.MakesurethereisnoleakontheINLETGASLINES.Checkwithsoapywater.D5.2 Preparation of cell test on the test stationTimerequiredforthisstep:~5minutes
i. Inserttheoutsidethermocoupleintotheendofalittleholeonthegraphiteplateofthecellhardwareformeasuringthecellstemperature.
Caution:Makesurethatthethermocouplestaysattheendoftheholeandusethescotchtapetokeepitinplace,ifneeded.Ifthethermocoupleisnotinplace,thecellwillbeOVERHEATEDtomaintainasetpointtemperature(acellfailure).
ii. SwitchboththecathodeandanodegasvalvesontheteststationtoN2gas.D5.3 Operation of computer to start up cellTimerequiredforthisstep:~5minutes
i. TurnonComputer1ANDFuelCellLoadUnit1.ii. SelecttheiconforFuelCellsoftwareonMSWindowsandopenit.iii. AmenuboxtitledSETUPCELL(SeeFigureD2)willpopup.Setcellsurfaceareaas
APPROPRIATEfortheMEAtested(usually25cm2).Setcelltemperatureat25oCNote. If the Beep box is checked, FuelCell software program will produce a beep from thecomputerspeakerwhentheMinorMaxlimitsareexceeded.
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FigureD2.SetupCellMenuiv. AnothermenuboxtitledSetupFuelFlow(SeeFigureD3)willpopup.
Settheflowratesat: Anode- MinimumFlow:0.4L/min
- Loadbasedflow:0L/min/cell+0.023L/min/Amp/cell(notusedinthiscase)- Temperature:25oC
Cathode:- MinimumFlow:0.4L/min- Loadbasedflow:0L/min/cell+0.066L/min/Amp/cell(notusedinthiscase)
Temperature:25oC
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FigureD3.SetupFuelMenuD5.4 Crossover and Cyclic Voltammetry Tests
Timerequiredforthisstep:~40minsNote.Thisisaseriesofteststodeterminethebasicsoundnessofthecelltoseeifitmeetsminimumrequirements.
i. Onthesideoftheteststation,switchANODEgasvalvetoH2andCATHODEgasvalvetoN2.
ii. ConnectWORKINGandSENSEelectrodestotheCATHODEandtheCOUNTERandREFERENCEelectrodestotheANODE.(SeeFigureD4)
iii. TurnonthePrincetonAppliedResearch263A(ConnectedtoComputer3).iv. TurnonComputer3,whichisusedformeasuringshortcircuit,crossovercurrent
andcyclicvoltammetry.v. SelecttheiconforCorrWare2softwareonthemainscreen,anddoubleclickitto
activatetheprogram.vi. Rightclickat PotentiodynamicandselectSetupcelloption
vii. Setcellsurfaceareato25cm2andthenclickOK(seeFigureD5)viii. RightclickatPotentiodynamicandselectSetupinstrumentoption.Set
bandwidthtohighstability
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ix. DoubleclickPotentiodynamictowaituntiltheOCPbecomeslowerthan0.1V.NamefileaccordingtotheIonomemDatabasefiles(SeeSectionD4.4)andselectwhereitwillbesaved.Select4mV/sasthescanrate.
Note.Thisopencircuitvoltagevaluewouldbeshownattheupperrightcornerofthemenupanel
x. SelectPotentiodynamicfromexperimenttypesandclickthebuttonforMeasureSelectedintoolbarandbeginthismeasurement
Note.Thisgreenlabelisshowninthetoolbarofthemenupanel.xi. RightclickatCyclicVoltammogramandselectSetupinstrumentoption.Set
bandwidthtohighspeed.xii. DoubleclickCyclicVoltammogramandnamefileaccordingtotheIonomem
Databasefiles(SeeSectionD4.4)andselectwhereitwillbesaved.Select30mV/sasthescanrate.
xiii. SelectCyclicVoltammogramfromexperimenttypes.xiv. ClickatthebuttonforMeasureSelectedintoolbarandbeginthismeasurement;xv. TurnoffthePAR263Awhenfinished.
xvi. Disconnecttheelectrodes(working,counter,sense,andreference)fromthecellhardwareplates
WorkingElectrode Counter
Electrode
Cathode
AnodeFigureD4.ConnectionofElectrodewithFuelCellHardwareforCO/CVMeasurements
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FigureD5.CorrWareSetupCellMenuD5.5 Humidification of the MembraneTimerequiredforthisstep:~3.5hoursNote.Thisstepisperformedtointroducewaterintothemembranetoimproveits ionicconductivityandreactantpermeability.
i. SwitchtheANODEgasvalvetoH2andCATHODEgasvalvetoN2.ii. ConnecttheLOADLINEStothefuelcellhardware:
Connectthecathode load line(red line)directlywiththecathodemetalplateofthe fuelcell.
Connecttheanodeloadline(blackline)directlywiththeanodemetalplateofthefuelcell.Caution:Beverycertainthattheconnectionistight!
iii. InserttheSENSELEADSintotheholesoftheleadsonthefuelcellhardware: Insertthecathodesenselead(redline)directlyintotheholeintheredlineattachedtothe
cathodegraphiteplate Inserttheanodesenselead(blackline)directlyintotheholeintheblacklineattachedto
theanodegraphiteplateCaution:NeverconnectthesenseleadstothetestfixturewithoutthelargeLOADconnectionsbeingmadefirst.Failuretodothiswiththeloadunitactivemayresultindamagetotheload.
iv. ChangeallsetpointstotheHEATUPStep(40/50/50condition) Setcelltemperatureat40oC Set anode and cathode gas lines at 50 oC (If applicable). (Recall 10 oC higher than cell
temperature) Setanodeandcathodehumidifiercontrollersat50oC.
v. Afterthetemperaturesreachthesetpoints,holdittherefor5to10min.vi. Changeallsetpointstothe80/80/73condition:
Setcelltemperatureat80oC
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Set anode and cathode gas lines at 90 oC (If applicable). Anode and cathode gas linetemperaturesare510oChigherthancelltemperature(Tcell).
Onthetestpanel,setanodehumidifiercontrollersat80oC(100%RH) Onthetestpanel,setcathodehumidifiercontrollersat73oC(75%RH)
vii. Settheflowratesat: Anode
- MinimumFlow:0.17L/min- Loadbasedflow:0L/min/cell+0.021L/min/cell(for3stoichiometryofH2)
Cathode:- MinimumFlow:0.17L/min- Loadbasedflow:0L/min/cell+0.066L/min/cell(for4stoichiometryofAir)
viii. Maintainatthiscondition(H2/N2,80/80/73)tohumidifytomembranefor3hours.D5.6 Operation of the Cell in a Break-In ModeTimerequiredforthisstep:~3hoursminimumNote.Thistestisperformedtoletthecellcometoasteadystatewhileoperatinginabenignwayasafuelcell.
i. SettheconditiontoH2/N2,80/80/73oCcondition(maintainpreviousstep).ii. Onthesideoftheteststation,keeptheANODEgasvalveonH2 andswitchthe
CATHODEgasvalvetoAir.iii. Wait until the cell voltage (which is the open circuit voltage at this point)
stabilizes.(~3minutes).Thenrecordtheexactopencircuitvoltage.Note1.Thevalueofopencircuitvoltagewillincreasewiththetime.Justwaituntilitisstable.Note 2. NEVER leave the cell at the OCV (Open Circuit Voltage) for more than 5 minutes.Platinum and carbon will corrode and cause performance decay. While changing conditionswithfuel(hydrogen)andoxidant(air/O2)present,alwaysapplyloadat100400mA/cm2.ThisistonotleavethecellatOCVtoavoidcellcorrosion.
iv. ClickApplyFuelandApplyLoadbuttons.v. Setthecellvoltageat0.55V.RecordtheTOTALcurrentdensitytoValue#1(t=0
hours).vi. Holditforonehour,recordtheTOTALcurrenttoValue#2(t=1hour)vii. Holditforanotherhour,recordtheTOTALcurrenttoValue#3(t=2hours).viii. RepeattherecordingeveryhouruntiltheTWOlastcurrentvaluesarewithin5%
ofeachother.(Usuallytakes35hours)D5.7 Cool-Down Procedure
Timerequiredforthisstep:~1houri. Setthecelltemperatureto80/60/60oCNote1.Thecelltemperaturemustbeabout1020oCabovethesaturatortemperaturesduringcooldown.Note2.Watercanbeaddedtothesaturators,andinsulationcanberemovedfromthecelltopromotecooldown.
ii. Whilewaitingfortemperaturestoreachthefirstsetpoints,disconnectthepositiveloadcable,toprotectfromcurrentleak.
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iii. Settheminflowrateontheanodeandthecathodeat0.2L/min.iv. SwitchthecathodevalveonthesideofthestationtoN2forpurgingthecell.v. Waituntilthevoltagefallsto0.4V,thenswitchtheanodevalvesinthefrontpanel
ofthestationtoN2forpurgingthecell.vi. Afterthetemperaturereaches80/60/60oC,setitto60/50/50,then50/40/40,then
0/0/0.vii. Wait until the cell temperature, the humidifier temperatures, and the gas line
temperaturesareallbelow50oC.viii. Turnoffthepowerofheaterforhumidifiers.
ix. Settheanodeandcathodeflowratebacktozero.x. Click"Exit"toclosetheFuelCellsoftware.
xi. TurnofftheFuelCellLoadUnitxii. Closeallvalvesofthegascylinders.
xiii. Closeanodeandcathodevalvesoftheteststation.
D6Day2TestD6.1 Crossover and Cyclic Voltammetry TestsTimerequiredforthisstep:~0.5hourRepeattheprocedureformeasuringCOandCVonday1.D6.2 Polarization curve measurement at 80 oC (Air/O2alternating)Timerequiredforthisstep:~7hours(Air/O2/Air)Note.Thistestisperformedtodeterminethecellperformanceatatmosphericpressure,whichistheconditionwheretheelectrolyteisnearsaturation.
i. Settheflowratesasdoneforthehumidification.ii. KeeptheANODEgasvalveonH2 andswitchtheCATHODEgasvalvetoAir(1st Air
run).iii. LetthecellreachOCV(~23min). RecordOCV.iv. ClicktheApplyFuelbuttononthemainwindowasshowninFigureD6.v. ClicktheApplyLoadbuttononthemainwindowasshowninFigureD6.
vi. Apply400mA/cm2load. Maintainuntilvoltageisconstant.vii. IfnoexperimentsarelistedundertheSetupExperimentspanel,clickonNew
button on the right of the panel, and select Arbitrary control. If there areexperimentslistedintheSetupExperimentspanel,doubleclickoneofthem.
viii. ThemenuboxtitledSetupArbitraryControlExperimentwillpopupix. Chooseanameandlocationforthedatafile(filewiththeresultsoftheexperiment).x. Selectanappropriatecontrolsetupfilefortheexperiment,thenclickOK
Note. ControlSetupfilesaretextfiles(i.e..txtfiles)thatareusedtocontroltheload. Wearecurrentlytestingthefollowing loads:0,10,20,40,60,80,100,200,300,400,500,600,700,800,900,1000,1100,1200,1300,1400,1500,1600,1700,1800,1900,2000mA/cm2,heldateachpointfor5minutes.
xi. ClicktheRunCellButtononthemainwindow
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xii. SelectGraphsinmenubar,thenclickvsTimecommandandclickVoltageasshowninFigureD7.
xiii. ThemenuboxtitledGraphs#1willpopup.xiv. Change Background data to Experiment data at the upperright corner of this
menuboxxv. SoftwarestartsdataacquisitionforaCellVoltagevs.Timeplot
xvi. Wait until the experiment is finished. While the experiment is in progress, checkregularlythatthewaterlevelinthehumidifierisnotbelowtheminimumlevel. AlsocheckthattheexperimentisprogressingwithoutjumpingtoOCV.
xvii. Aftertheexperimentisfinished,theloadshouldreturntowhateverloadwasbeingusedpriortotheexperiment,inthiscase400mA/cm2.
xviii. SwitchthecathodevalveonthesideofstationtoO2andwaituntilvoltagestabilizes.RepeatthemeasurementinO2(atthesametemperature).
xix. After the measurement on O2 is finished, switch the cathode valve back to Air.Repeatthemeasurementforair(2ndAirrun).
FigureD6.MainWindowforFuelCellsoftware
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FigureD7.ChooseVoltagevs.TimegraphD6.3 Crossover and Cycl ic Voltammetry Tests at 80/80/73Timerequiredforthisstep:~0.5hourRepeatthecrossoverandcyclicvoltammetryprocedurefromday1at80/80/73.D6.4 Hold at 400 mA/cm2overnight
D7Day3TestD7.1 Performance Measurement at 80/80/73 (Air/O2Alternating, 1.5 atm)Timerequiredforthisstep:~6hours
i. Pressurizecellto1.5atm.ii. Runthecellatthe80/80/73conditionwithH2/Air.
iii. Waituntilthewholesweepmeasurementisfinishedthenrepeatwithoxygenandagainwithair.
D7.2 Performance Measurement at 100/90/90, Air, 1.5 atmTimerequiredforthisstep:~2hours
i. Changethetemperaturestothe100/90/90condition(usingH2/Air) Setcelltemperatureat100oC
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Setanodeandcathodegaslinesat110oC,ifapplicable Setanodehumidifiercontrollersat100oC
ii. Apply400mA/cm2ofload,andwaituntiltemperaturesandvoltagestabilizeiii. StartthemeasurementoftheperformanceusingH2/air Waituntilthewholesweepmeasurementisfinished.
D7.3 Hold over night at 400 mA/cm2
D8Day4TestD8.1 Performance Measurement at 100/90/90 (O2/Air Alternating, 1.5 atm)Timerequiredforthisstep:~3hours
i. Runtheperformancetestatthe100/90/90conditionwithH2/O2ii. Waituntilthewholesweepmeasurementisfinishedthenrepeatwithair.
D8.2 Crossover and Cyclic Voltammetry Tests at 120/90/90Timerequiredforthisstep:~1hour
i. Releasepressureoncelltoambientii. Changethetemperaturestothe120/90/90condition Setcelltemperatureat120oC Setanodeandcathodegaslinesat125oC(NOT10oChigherthanTcellasusual) Onthetestpanel,setanodehumidifiercontrollersat90oC(sameasprevious)
iii. RepeattheCO/CVprocedureofDay2D8.3 Performance Measurement at 120/90/90 (Air/O2Alternating, 1.5 atm)Timerequiredforthisstep:~3hours
i. Pressurizecellto1.5atm.ii. Changecathodegastoair
iii. Apply400mA/cm2ofloadandwaituntilvoltagestabilizesiv. StartthemeasurementoftheperformanceusingH2/Airv. SwitchtoO2,apply400mA/cm2whilewaiting
vi. RuntheperformancetestwithH2/O2thenwithH2/AirD8.4 Reduce Cell temperature to 100C and hold overnight at 400 mA/cm2
D9Day5TestD9.1 Crossover and Cyclic Voltammetry Tests at 100/90/90
Timerequiredforthisstep:~1houri. Releasepressureoncelltoambient
ii. Changetemperatureto100/90/90conditioniii. RepeatthecrossoverandcyclicvoltammetryprocedureofDay1
D9.2 Performance Measurement at 100/90/90 (Air/O2Alternating)Timerequiredforthisstep:~6hoursminimum(Air/O2)
i. Pressurizecellto1.5atm
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ii. Changecathodegastoairiii. Apply400mA/cm2ofloadandwaituntilvoltagestabilizesiv. StartthemeasurementoftheperformanceusingH2/Airv. Whenmeasurementisfinished,switchtoO2andapply400mA/cm2whilewaiting
vi. RuntheperformancetestwithH2/O2.vii. Whenmeasurementisfinished,switchtoairandapply400mA/cm2whilewaiting
viii. RuntheperformancetestwithH2/Air.D9.3 Stabili ty Test at 100/90/90 (H2/Air, 400 mA/cm
2, 1.5 atm, Days 5, 6, and 7)
UnderSetupexperimentsclickonNewbuttonontherightofthepanelandselectConstantcurrent
Savethefileunderanappropriatenameandinputtesttime(~70h)andcurrent(400mA/cm
2)
Collectcondensatewaterfromanodeandcathodeexhausteachmorningandevening,inseparate,labeledvials(endupwith12vialstotal).Analyzecondensatewaterforfluoride
ions
according
to
Appendix
E.
D10Day8TestD10.1 Crossover and Cyclic Voltammetry Tests at 100/90/90Timerequiredforthisstep:~0.5hour
i. Releasepressureoncelltoambientii. RepeatthecrossoverandcyclicvoltammetryprocedureofDay2
D10.2 Performance Test at 100/90/90 (Air/O2Alternating, 1.5 atm)Timerequiredforthisstep:~6hours
i. Pressurizecellto1.5atmii. RepeatPerformancemeasurementat100/90/90fromday5
D10.3 Cool-downi. Setthecelltemperatureto80/60/60.
Note1.Thecelltemperaturemustbeabout1020oCabovethesaturatortemperaturesduringcooldown.Note2.Watercanbeaddedtothesaturators,andinsulationcanberemovedfromthecelltopromotecooldown.
ii. While waiting for temperatures to reach the first set points, disconnect thepositive loadcable,toprotectfromcurrentleak.
iii.
Setthe
min
flow
rate
on
the
anode
(H2)
and
the
cathode
(air)
at
0.2
L/min.
iv. SwitchthecathodevalveinthefrontpanelofthestationtoN2 forpurgingthe
cell.v. Waituntilthevoltagefallsto0.4volts,thenswitchtheanodevalvesinthefront
panelofthestationtoN2forpurgingthecell.vi. Afterthetemperaturereaches80/60/60,setitto60/50/50,then50/40/40,then
25/25/25.
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vii. Waituntilthecelltemperature,thehumidifiertemperatures,thesaturatedgaswater,andthegaslinetemperaturesareallbelow50oC.
D11Day9TestD11.1 Repeat the crossover and cyclic voltammetry procedure of Day 2 (at room
temperature)
D11.2 Leak test per Appendix C
D11.3 Resistance Test per Section D5.1
D11.4 Shut-down and Remove from the test standi. Turnoffthepowerofheaterforhumidifiers(ifapplicable).ii. Settheanodeandcathodeflowratebacktozero.iii. Click"Exit"toclosetheFuelCellsoftware.iv. TurnofftheFuelCellLoadUnitv. Shutdowncomputer.vi. Closeallvalvesofthegascylinders.vii. Closeanodeandcathodevalvesoftheteststation.viii. Disconnectgastubingandelectricallinefromthecellhardware.
D11.5 Post-testi. Measureboltloadii. DisassembletheCelliii. ConductvisualInspectioniv. BagandSealComponentsWith10dropsofDIWaterineachBag
D12Troubleshooting:HardwareproblemsINDICATION CAUSE CORRECTION
yNopowerwhenunitisturnedONyACPowernotavailabletomodel890
yFuseonrearpanelofthecontrolunitmaybeblown
yReplacewith4A,slowblow3AGtypefuse
yNoheaterpoweravailableforoneormoreofthetemperaturecontroller
yCheckinternalfusesthatprotectthetempcontrolleroutput.
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yAlarmswhenFUELON yFuelGasunitcables yCheckgaspressuresandlowbuttonispressedinsoftware notconnected
yModel890FuelSystemInterfaceBoxnotproperlyconnected
pressuresafetyswitchwiring.yLowgaspressurealarmswitchesmustbeclosedforalarmstobeoff.
yNoloadcurrentwhenloadisturnedON yLoadcablesnotconnected
ySenseleadsnotconnectedorreversedySenseleadprotectionfuse(internalfuse)blown
yRemoveallpowertosystemanddisconnectanodecellleadandanodesenseleadfirstyResistanceshouldmeasurebetween10and15WyIfincorrect,removetheunitcoverandcheckthefusebyremovingitfromitssocket.
yInadequatecoolingairflowcausingovertemperatureshutdown
yCheckcooling restrictionsyProlongedovertemperatureoperationmaydamagetheloadelectronics.
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D13ChartSummarizingDay-to-DayActivitiesDay Time(h) Temp GasA GasC Action Notes1111
0.53.5318h
RT80/80/7380/80/73
N/AH2H2H2
N/AN2AirN2
SetupHumidifyBreakinCooldown
Includesleaktest,resistance,etc.At0.55V
22222
0.52.5220.57.5h
25/25/2580/80/7380/80/7380/80/7380/80/73
H2H2H2H2H2
N2AirO2AirN2
CO/CVIVIVIVCO/CV
33333
222129h
80/80/7380/80/7380/80/