IT-SOFCs: Overview of Stack Size Scaling Eﬀorts* and Red ...

IT-SOFCs:OverviewofStackSizeScalingEfforts*andRed-OxRobustAll-CeramicAnodeCellBasedStacks**

BryanBlackburn(PI)06/14/2018

RedoxKeyContributors:SeanBishop,LuisCorrea,ColinGore,SteluDeaconu,Tom

Langdo,Ke-jiPan,LeiWang

REDOXPOWERSYSTEMSLLC

*DE-FE0026189(NETL-1)**DE-FE0027897(NETL-2)

16/14/18

AGENDA

•  NETL-1Overview–  Stackassemblyimprovements–  Stackdesignupdates–  Results&Analysis–  Planmovingforward

•  NETL-2Overview–  All-ceramicanode–  MaterialscharacterizaXon–  MaterialsScale-up(sizeandproducXonquanXty)–  Red-Oxcyclingofstack–  EconomicsAnalysis

REDOXPOWERSYSTEMSLLC 26/14/18


HIGHPOWER,LOWCOSTSOLIDOXIDEFUELCELLSTACKSFORROBUSTANDRELIABLEDISTRIBUTEDGENERATION

(DE-FE0026189)

36/14/18

StackAssemblyImprovements

–  Assemblygetsmuchharder(andmuchmore$$$)asstacksgetbigger–  Needbe^erautomaXontohaverepeatabilityinassemblyprocess–  Needbe^ermetrologytoensurethatqualitycontrolpresent


CurrentStatus:StackAssemblyImprovements

REDOXPOWERSYSTEMSLLC 5

•  Dedicatedstackassembly,metrology,andpost-testcatalogingspace

•  OpXcalprofilometryusedaspartofQC

•  ExpandedtomulXplestackassemblystaXonsandkitpreparaXonareas

•  StackassemblyusesfullyintegratedControlsSodware-Tracksuniformityofstackdisplacementduringassembly-Sodwareintegratedwithothermetrology(e.g.,acousXcemissionsensors)

•  Databasetrackingofallrelevantdata

6/14/18

Insitustressmonitoringofcellsduringstackassemblydev.


High Stress

High Stress

Crack region

Crack region DistributedForceSensing(DFS)•  SpaXalstressmonitoringreal-Xmeduringstackassembly

•  CorrelaXonofregionsofhighstresswithmechanicalfailure

•  AcousXcemissionsalsomonitoredspaXallyformechanicalfailurelocaXonidenXficaXon

0s 30s 75s

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ExpandabletoenVrestack

MulX-PhysicsModelingToolForStackImprovements


• Custom3DcomputaXonalmodeltakesintoaccounttheuniquethermochemicalandphysicalproperXesoftheRedoxmaterialsasderivedfrommorefundamentalmaterialsandelectrochemicalmeasurements

• Modelconsidersimpactsofleakagecurrent(electroncurrent)ontheOCVdropsfromtheoreXcalNernstpotenXalduetoover-potenXalsassociatedwiththeelectrolyteandelectrodes

• ModelalsocapturesthekineXcsofelectrochemicalandheterogeneousinternalreformingreacXonsintheanode

Figure 3. a) Plot of V-i curves for 600°C inlet for H2, reformate with no CH4 reformer slip and reformate with high CH4 reformer slip. Fuel flow is fixed at 80% fuel utilization for 0.7 V for each fuel. b) Plot of 2-D current distribution for the three anode fuel feeds operating at 0.7 V and 600°C and a fuel utilization of 80%.

With the modeled Ni surface area in the anode support layer, the modeled rates of

internal CH4 reforming are adequate to drive CH4 mole fractions to around 20% of their inlet value at 600°C and near 10% of their inlet value at 650°C. As shown in Figure 5 for the 50% CH4-slip reformate, at 0.7 V CH4 is rapidly consumed in the first 1.0 cm of the anode and then slowly decays over the rest of the channel as the reforming reaction is slowed in part by transport to the anode support layer. At 650°C inlet, Figure 5b shows that reforming occurs rapidly in a narrow region near the channel/support layer interface whereas at 600°C, the reaction is more evenly distributed through the depth of the support layer. These results suggest the critical need for using such models to design intermediate-temperature SOFCs for controlling distribution of internal reforming.

50% CH4 slip No CH4 slip H2 (b)

(a)

Figure 2. Mole fractions of (a) H2 (b) CH4, and (c) CO for 0.7 V at standard fuel utilization for no methane slip condition at 600°C inlet. The scales are different for each species and based on their relative minima and maxima.

(a) H2

(b) CH4

(C) CO

(a)MolefracXonofH2for0.7VatstandardfueluXlizaXonfor0%CH4slipat600°Cinlettemp.(b)2DcurrentdistribuXonfor3anodefuelfeedsoperaXngat0.7Vand600°CandaUfof80%

!

DetailedSingleChannelModel

LSFC-GDCcathode

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ExampleofModelingResults


T(◦C)

Flow

Dire

cOon

TemperatureprofileofthestackcelloperaXngat1W/cm2

CellEdge

(MPa)

•  Integratedthermo-mechanicalstudybasedontemperatureprofileofstackissimilartoiteraXve-solvedsinglechannelmodelingresults

•  Stressesincrease(upto10MPa)astemperaturesriseinthecenterofthestackandconcentratemostlyinthecenterandatendedge

•  Modelcurrentlybeingusedtoevaluateenhancementsforimprovedthermalmanagement

StressdistribuXonofthestackcelloperaXngat1W/cm2

H2asfuel

86/14/18

StackDesignUpdates


•  TieRodHoles,Endplate/ICGeometry– OpXmizedtominimizestressoncellsandachievelowercross-overleakrate

•  SealspecificaXons– Minimumsealwidthsanywherewithinstack

•  Inlet/outletspecificaXons–  Increasedareatoaccommodateflowsinlargerstacks

•  Plenum/FlowfieldspecificaXons–  Basedonotherchanges,modifiedtoensureuniformflowdistribuXonfrominlettochannels

96/14/18

CellProcessing&MetrologyImprovements


Cellandmaterials:ParXclesizeanalysis,bulkconducXvity,XRD,etc. OpXcalprofilometryIn-planeresistance Pasteuniformity

andviscosity

Fullyqualified,semi-automaXcscreenprinXngprocessforcathodeandcontacts

106/14/18

Scalingtheupdatedstackdesign


Stack Size Anode -> Cathode X-Over Cathode -> Anode X-Over

250 W 0.18% 0.21%

350 W 0.69% 0.29%

650 W 0.33% 0.46%

750 W 0.3% 0.29%

116/14/18

650WStack

350WStack

Pow

er D

ensi

ty (W

/cm

2 )

StackScale-up:1.15kWStack


•  >1.15kWstackdemonstrated•  Gaspreheatwithplateheatexchangers•  AddiXonalperformanceanXcipatedwithopXmizedthermalmanagement•  Modelingpredictsdesignshouldhold>2.5kW•  New“labreformer”justverified>2.5kW

126/14/18

DataAnalysis:ThermalManagement


•  MulX-physicsmodeling–  Modelvalidatedusingcalculated

celltemperaturesfromexperimentallymeasuredvalues

–  Modelthenusedtoprobewaystoimprovethermalmanagement

•  Temperaturegradientacrosseachcellwithin1.15kWstack–  Largestgradientsneargas

manifold–  Majorityofthecellshave

gradientof~25°Cto30°C

136/14/18

Redox’sNaturalGasTestFacility(NGTF)


•  DedicatedsiteforconXnuousNGuse,nogasbo^lesrequired–  Desulfurizedandrawfeeds

available•  Presentlycanaccommodate

2.5kWstacksineachof2teststaXons–  Testbenchisdesignedforrobust

operaXonoverlongperiodsofXme

•  SeveralNGReformingsystemsavailable,upto9kWstackfeed

•  Secondtestbenchhousesanislandedsystemprototype:onlyfacilityXe-inisNG

2.5kWStackTestKilns

StackTestHood BOP/SystemHood

Lab-Controlled

FuelReformer(s)

146/14/18

Lab-ControlledPipelineNGSteamReformer

H2 CH4 CO CO2 H2O

Feed to Reformer 0% 100% 0% 0% 5.6:1 S:C

Feed to Stack (GC Measurement) 67.5% 10.1% 8.8% 13.2% Bal.

Thermodynamic Equilibrium Values

78.1% 0.1% 7.8% 13.7% Bal.


Reformer

Meteredsteam

Desulfurized,pipelinenaturalgas

FeedtoStack

FeedtoReformer

Stacktestkiln

Reformercapacitygoodfor>2.5kWstack

ShakeDownTest#1(650°C)

ShakeDownTest#2(600°C)

156/14/18


Red-OxRobustSOFCStacksforAffordable,ReliableDistributedGeneraOonPowerSystems

(DE-FE0027897)

166/14/18

Red-OxStabilityNeededinSOFCs

JournalofPowerSources195(2010)5452–5467

Red-oxcyclescanbeexpectedduringlong-termfuelcelloperaXon•  InterrupXonsinfuelsupply•  TransientSOFCoperaXon(e.g.,shutdown)

Ni-cermetanodespronetomechanicalfailureduringredoxcycling

~69vol%expansionofNiàNiO

SoluXon:AllceramicanodeàsmallΔoxygen=smalldimensionalchange(0.4vol%)

Line

ar

Expansion[%

]

650oC

0.4vol%

NocracksaZer9redoxcycles!


All-CeramicAnodeSOFCPerformance

•  HighpowerdensiXes•  ~0.75W/cm2@550°C•  ~0.3W/cm2@450°C

•  AcceptableelectronicconducXvity

Buboncelldata AnodeelectricalconducVvity


SealandGen.1Cell(Ni-Cermet)Red-OxCyclingStability

Ni-Cermetcelladertest

Cracks

Gascrossover(anode↔cathode)measuredduringRed-Oxcycling(650oC)

Fuel

Air

FuelAir

Ni-cermethalf-cell

Al2O3sheet

•  Ni-cermethalf-cell:largecrossoverevenader3cyclesofonlyH2↔N2(<0.02%O2),thenfailscatastrophically

•  SealswithAl2O3sheet“mockcell”showsmallincreaseincross-overwithcycling(H2↔air)

-Dilatometry:sealshrinksby~2%ader>20red-oxcycles

~1%half-cellexpansiononoxidaXon

Lineardilatometryat650oC


SOFCTesXngCapabiliXes

BiologicBCS-815

•  8-channel•  15A/channel•  PotenXostat•  Impedanceanalyzer•  àMini-cellshortstack

and5x5stacktesXng


ScalingforAll-CeramicAnodeManufacturing

•  ProducXon-scaletapecasXngandlaminatemanufacturewithproducXonpartners

•  ProducXon-scalecellfiringwithproducXonpartners•  MulXplecommercial-scalecastsofall-ceramicanodeproducXontape

•  Successfullyfabricatedandfired>3010cmby10cmlaminates

•  ProducXoncastalternaXveelectrolyteandanodefuncXonallayerstailoredforall-ceramicanodecells

•  FutureworkinvolvesintroducingmodifiedanodestructureinproducXonrunsandconXnuedcasXngforlarge-scalestackneeds


FlatAll-CeramicAnodeCells

CellProfile

10cmx10cmAll-CeramicAnodeCell

•  Achievedveryflatall-ceramicanodecellsfabricatedatR&D,and“producVon”scale

•  Demonstratedfiringinlarge“producVon”kilns


CellProfileOnly0.039μmvariaXon(max–min)

Profileslice

6/14/18

3-cell5cmx5cmAll-CeramicAnodeStack

600°C

•  FirststackdemonstraVonofR&D-scalefabricatedcells•  LowASR~0.19Ω-cm2at600°C



600°C

1ststackdemonstraVonof“producVon”castandlaminatedGen-3cells



<1Win2017 154Win2018

600°C154W

“ProducXon”materials


*Note:CellperformancenotfullyopXmized.AddiXonalpoweroutofsamesizestackbyendofproject.

Red-OxCyclingofHalf-Cells

•  CellexpandsduringreducVonandshrinksreversiblyduringoxidaVon•  Likewise,conducVvityincreasesinH2anddecreases,reversibly,inair

DilatometryandconducXvitymeasurementofall-ceramicanodehalf-cellsample


MicrostructureAderRed-OxCyclingOpVcalmicroscopeimagesofelectrolyteside


Nofracture Nofracture Nofracture

Air<->H2

Cracks

Ni-CermetCell

All-CeramicAnodeCell

Ader1-2red-oxcycles

Ader~10-20red-oxcycles

6/14/18

Red-OxCycling5x5SOFCs

•  3red-oxcycleswithminimalASRandOCVdegradaXon

•  Furthercyclingàincreaseingascross-overindicaXngcellfracture

•  FutureworkincludesconXnuedanodestructuremodificaXon

Improvementstoanodestructureof5x5cellsenablesimprovedred-oxcycling@600°C

Stablegasx-over

StablevoltageH2onanode

N2*on

anode

*N2has~0.1%O2impurity

Red-oxcycles

~StableASRonfirst3red-oxcycles


H 2OatC

atho

de(a.u.)

AcceleratedTesXng:CathodeDegradaXon

GEN1mini-cellsagedexsituat650°CinairforindicatedVme,thentested

1,000h300h20h

LowfrequencyZ(ohmic+polarizaXon)

HighfrequencyZ(ohmic)

•  IncreasedexsituagingresultsinlessIniValohmicburn-in(<60h)àohmicburn-intakesplaceduringexsituaging,likelycathode/contactrelated

•  Similarly,polarizaVonburn-inannealedintoexsituagedsamples•  Long-termincreaseintotalZexpectedinSOFCtestappearstobe“added”to1,000hexsitu

annealedsample

“Burn-in”


AcceleratedTesXng:StorageCondiXons

EffectofRHonLifeat250C 100%IncreaseinResistance

1500%IncreaseinResistance

%RH LifeinHours(95%Reliability)

LifeinHours(95%Reliability)

40 229178 5.71*1010 60 170 57584 80 4 53 95 0.7 2

ModeloflifeunXlfailure

Datapoints

FailuredistribuXon

•  DevicelifeVmedependssignificantlyonfailurethresholdcriteria

•  LifeVmeisdramaVcallyshorteratveryhighhumidity(≥60%)at25oC

•  FutureworkincludesaddiVonalRH-Tstudiestorefinemodelforall-ceramicanodeandcathodematerials


Measurementofall-ceramicanodetestspecimen.SimilarbehaviorfoundonLSCFandLSC.

$0

$50

$100

$150

$200

$250

$300

$350

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000

CumulativeDiscountedCost($)

Time(hours)

DiscreteEventSimulator

NGpressureboost Reformer

Waterboiler

Stack(s)

Condenser

AirBlower

HX

HXDCpowertransformer Inverter

Hotpipes/valves

Coldpipes/valvesElectricalCable

HX:Heatexchanger

FuelProcessing SOFCOperation Powerconditioningandsystemcontrols

ControlSystem

•  SimulatescostofsystemoverlifeXmeofwarranty

•  IncludesesXmatesofmean-Xme-to-failure(MTTF)ofsystemcomponents

SchemaVcofsystemdesignapproximaVon

Modeloutput

•  IniValdeploymentandstackreplacementslargestcostcomponentsininiValmodel

•  Stackreplacementsincludefailuredueto“criVcalevents”

•  FutureworkincludesimprovingesVmatesofMTTFs,costs,andmodeluVlity

CostfromfailuresonmulXpleinstallaXons


NaturalGasPipelineFailures

Pipelinemodel FailurefrequencypredicXon

•  IncludesesVmatesfromliteratureonfailurefrequencyofdifferentpipesizes1–mostfailuresoriginatefrom“dig-ins”

•  NaturalgaspipelinesesVmatedtonotfailfor>20years

1JHouseEnvironmental,PipelineRiskAnalysis-MountainHouseSpecificPlanIII,2004.h^p://www.sjgov.org/commdev/cgi-bin/cdyn.exe/handouts-mtnhouse_EIR_Appendix_K_Pipeline_R?grp=handouts-mtnhouse&obj=EIR_Appendix_K_Pipeline_R(accessedOctober16,2017).


(MonteCarlobasedonpipelinemodel)

ProjectsSummary

DE-FE0026189(NETL-1)•  ImprovedstackassemblyandQCprocedures•  Stackscale-upforimproveddesign:1.15kWstackdemonstrated•  >2.5kWlabreformerverifiedalongwithrestofsetupfortesXng2.5kWstack•  CellproducXonrampeduptobeginmovingtoward2.5kWstack

DE-FE0027897(NETL-2)•  Improvedflatnessoffiredall-ceramicanodehalf-cells•  Scaledupall-ceramicanodeproducXonwithtapecasts,laminaXon,andfiring•  Successfullytested10-cell10x10all-ceramicanodestack•  Manufacturingcostanddiscreteeventsimulatormodelsinworkablestate,

refiningwithimprovedparameters


Acknowledgments


• NETLProjectManager•  SethLawson

• UniversityofMaryland•  CALCE(accelerated/lifecycletestplans/economicmodeling)•  EnergyResearchCenter(fundamentalR&D)

6/14/18

IT-SOFCs: Overview of Stack Size Scaling Eﬀorts* and Red ...

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