Solid oxide electrolyzer cell - Wikipedia

A solid oxide electrolyzer cell (SOEC) is a solid oxide fuel cell that runs in regenerative mode to achieve the electrolysis of water (and/or carbon ... Solidoxideelectrolyzercell FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Typeoffuelcell SOEC60cellstack. Asolidoxideelectrolyzercell(SOEC)isasolidoxidefuelcellthatrunsinregenerativemodetoachievetheelectrolysisofwater(and/orcarbondioxide)[1]byusingasolidoxide,orceramic,electrolytetoproducehydrogengas[2](and/orcarbonmonoxide)andoxygen. Theproductionofpurehydrogeniscompellingbecauseitisacleanfuelthatcanbestored,makingitapotentialalternativetobatteries,methane,andotherenergysources(seehydrogeneconomy).[3]Electrolysisiscurrentlythemostpromisingmethodofhydrogenproductionfromwaterduetohighefficiencyofconversionandrelativelylowrequiredenergyinputwhencomparedtothermochemicalandphotocatalyticmethods.[4] Contents 1Principle 2Operation 3Materials 3.1Electrolyte 3.2FuelElectrode(Cathode) 3.3OxygenElectrode(Anode) 4Considerations 4.1Delamination 5Applications 6Research 7Operatingconditions 8Seealso 9References 10Externallinks Principle[edit] Solidoxideelectrolyzercellsoperateattemperatureswhichallowhigh-temperatureelectrolysis[5]tooccur,typicallybetween500and850 °C.Theseoperatingtemperaturesaresimilartothoseconditionsforasolidoxidefuelcell.Thenetcellreactionyieldshydrogenandoxygengases.Thereactionsforonemoleofwaterareshownbelow,withoxidationofwateroccurringattheanodeandreductionofwateroccurringatthecathode. Anode:2O2−→O2+4e− Cathode:H2O+2e−→H2+O2− NetReaction:2H2O→2H2+O2 Electrolysisofwaterat298K(25 °C)requires285.83kJofenergypermoleinordertooccur,[6]andthereactionisincreasinglyendothermicwithincreasingtemperature.However,theenergydemandmaybereducedduetotheJouleheatingofanelectrolysiscell,whichmaybeutilizedinthewatersplittingprocessathightemperatures.Researchisongoingtoaddheatfromexternalheatsourcessuchasconcentratingsolarthermalcollectorsandgeothermalsources.[7] Operation[edit] ThegeneralfunctionoftheelectrolyzercellistosplitwaterintheformofsteamintopureH2andO2.Steamisfedintotheporouscathode.Whenavoltageisapplied,thesteammovestothecathode-electrolyteinterfaceandisreducedtoformpureH2andoxygenions.Thehydrogengasthendiffusesbackupthroughthecathodeandiscollectedatitssurfaceashydrogenfuel,whiletheoxygenionsareconductedthroughthedenseelectrolyte.TheelectrolytemustbedenseenoughthatthesteamandhydrogengascannotdiffusethroughandleadtotherecombinationoftheH2andO2−.Attheelectrolyte-anodeinterface,theoxygenionsareoxidizedtoformpureoxygengas,whichiscollectedatthesurfaceoftheanode.[8] Materials[edit] Solidoxideelectrolyzercellsfollowthesameconstructionofasolid-oxidefuelcell,consistingofafuelelectrode(cathode),anoxygenelectrode(anode)andasolid-oxideelectrolyte. Electrolyte[edit] Themostcommonelectrolyte,againsimilartosolid-oxidefuelcells,isadenseionicconductorconsistingofZrO2dopedwith8 mol %Y2O3(alsoknownasYSZ).Zirconiumdioxideisusedbecauseofitshighstrength,highmeltingtemperature(approximately2700 °C)andexcellentcorrosionresistance.Yttrium(III)oxide(Y2O3)isaddedtomitigatethephasetransitionfromthetetragonaltothemonoclinicphaseonrapidcooling,whichcanleadtocracksanddecreasetheconductivepropertiesoftheelectrolytebycausingscattering.[9]SomeothercommonchoicesforSOECareScandiastabilizedzirconia(ScSZ),ceriabasedelectrolytesorlanthanumgallatematerials.Despitethematerialsimilaritytosolidoxidefuelcells,theoperatingconditionsaredifferent,leadingtoissuessuchashighsteamconcentrationsatthefuelelectrodeandhighoxygenpartialpressuresattheelectrolyte/oxygenelectrodeinterface.[10]Arecentstudyfoundthatperiodiccyclingacellbetweenelectrolyzerandfuelcellmodesreducedtheoxygenpartialpressurebuildupanddrasticallyincreasedthelifetimeoftheelectrolyzercell.[11] FuelElectrode(Cathode)[edit] ThemostcommonfuelelectrodematerialisaNidopedYSZ.However,highsteampartialpressuresandlowhydrogenpartialpressuresattheNi-YSZinterfacecausesoxidationofthenickelwhichresultsincatalystdegradation.[12]Perovskite-typelanthanumstrontiummanganese(LSM)isalsocommonlyusedasacathodematerial.RecentstudieshavefoundthatdopingLSMwithscandiumtoformLSMSpromotesmobilityofoxideionsinthecathode,increasingreductionkineticsattheinterfacewiththeelectrolyteandthusleadingtohigherperformanceatlowtemperaturesthantraditionalLSMcells.However,furtherdevelopmentofthesinteringprocessparametersisrequiredtopreventprecipitationofscandiumoxideintotheLSMlattice.Theseprecipitateparticlesareproblematicbecausetheycanimpedeelectronandionconduction.Inparticular,theprocessingtemperatureandconcentrationofscandiumintheLSMlatticearebeingresearchedtooptimizethepropertiesoftheLSMScathode.[13]Newmaterialsarebeingresearchedsuchaslanthanumstrontiummanganesechromate(LSCM),whichhasproventobemorestableunderelectrolysisconditions.[14]LSCMhashighredoxstability,whichiscrucialespeciallyattheinterfacewiththeelectrolyte.Scandium-dopedLCSM(LSCMS)isalsobeingresearchedasacathodematerialduetoitshighionicconductivity.However,therare-earthelementintroducesasignificantmaterialscostandwasfoundtocauseaslightdecreaseinoverallmixedconductivity.Nonetheless,LCSMSmaterialshavedemonstratedhighefficiencyattemperaturesaslowas700 °C.[15] OxygenElectrode(Anode)[edit] Lanthanumstrontiummanganate(LSM)isthemostcommonoxygenelectrodematerial.LSMoffershighperformanceunderelectrolysisconditionsduetogenerationofoxygenvacanciesunderanodicpolarizationthataidoxygendiffusion.[16]Inaddition,impregnatingLSMelectrodewithGd-dopedCeO2(GDC)nanoparticleswasfoundtoincreasecelllifetimebypreventingdelaminationattheelectrode/electrolyteinterface.[17]Theexactmechanismbyhowthishappenneedstobeexplorefurther.Ina2010study,itwasfoundthatneodymiumnickelateasananodematerialprovided1.7timesthecurrentdensityoftypicalLSManodeswhenintegratedintoacommercialSOECandoperatedat700 °C,andapproximately4timesthecurrentdensitywhenoperatedat800 °C.Theincreasedperformanceispostulatedtobeduetohigher"overstoichimoetry"ofoxygenintheneodymiumnickelate,makingitasuccessfulconductorofbothionsandelectrons.[18] Considerations[edit] Advantagesofsolidoxide-basedregenerativefuelcellsincludehighefficiencies,astheyarenotlimitedbyCarnotefficiency.[19] Additionaladvantagesincludelong-termstability,fuelflexibility,lowemissions,andlowoperatingcosts.However,thegreatestdisadvantageisthehighoperatingtemperature,whichresultsinlongstart-uptimesandbreak-intimes.Thehighoperatingtemperaturealsoleadstomechanicalcompatibilityissuessuchasthermalexpansionmismatchandchemicalstabilityissuessuchasdiffusionbetweenlayersofmaterialinthecell[20] Inprinciple,theprocessofanyfuelcellcouldbereversed,duetotheinherentreversibilityofchemicalreactions.[21] However,agivenfuelcellisusuallyoptimizedforoperatinginonemodeandmaynotbebuiltinsuchawaythatitcanbeoperatedinreverse.Fuelcellsoperatedbackwardsmaynotmakeveryefficientsystemsunlesstheyareconstructedtodososuchasinthecaseofsolidoxideelectrolyzercells,highpressureelectrolyzers,unitizedregenerativefuelcellsandregenerativefuelcells.However,currentresearchisbeingconductedtoinvestigatesystemsinwhichasolidoxidecellmayberunineitherdirectionefficiently.[22] Delamination[edit] Fuelcellsoperatedinelectrolysismodehavebeenobservedtodegradeprimarilyduetoanodedelaminationfromtheelectrolyte.Thedelaminationisaresultofhighoxygenpartialpressurebuildupattheelectrolyte-anodeinterface.Poresintheelectrolyte-anodematerialacttoconfinehighoxygenpartialpressuresinducingstressconcentrationinthesurroundingmaterial.Themaximumstressinducedcanbeexpressedintermsoftheinternaloxygenpressureusingthefollowingequationfromfracturemechanics:[23] σ m a x = 2 P O 2 ( c ρ ) 1 / 2 {\displaystyle\sigma_{max}=2P_{O2}({\frac{c}{\rho}})^{1/2}} wherecisthelengthofthecrackorporeand ρ {\displaystyle\rho} istheradiusofcurvatureofthecrackorpore.If σ m a x {\displaystyle\sigma_{max}} exceedsthetheoreticalstrengthofthematerial,thecrackwillpropagate,macroscopicallyresultingindelamination. Virkaretal.createdamodeltocalculatetheinternaloxygenpartialpressurefromtheoxygenpartialpressureexposedtotheelectrodesandtheelectrolyteresistiveproperties.[24]Theinternalpressureofoxygenattheelectrolyte-anodeinterfacewasmodelledas: P O 2 a = P O 2 O x exp ⁡ [ − 4 F R T { E a r e a R e − ( E a − E N ) r i a R i } ] {\displaystyleP_{O2}^{a}=P_{O2}^{Ox}\exp\left[-{\frac{4F}{RT}}\left\{{\frac{E_{a}r_{e}^{a}}{R_{e}}}-{\frac{(E_{a}-E_{N})r_{i}^{a}}{R_{i}}}\right\}\right]} = P O 2 O x exp ⁡ [ − 4 F R T { ( ϕ O x − ϕ a ) − ( E a − E N ) r i a R i } ] {\displaystyle=P_{O2}^{Ox}\exp\left[-{\frac{4F}{RT}}\left\{(\phi^{Ox}-\phi^{a})-{\frac{(E_{a}-E_{N})r_{i}^{a}}{R_{i}}}\right\}\right]} where P O 2 O x {\displaystyleP_{O2}^{Ox}} istheoxygenpartialpressureexposedtotheoxygenelectrode(anode), r − e a {\displaystyler-e^{a}} istheareaspecificelectronicresistanceattheanodeinterface, r i a {\displaystyler_{i}^{a}} istheareaspecificionicresistanceattheanodeinterface, E a {\displaystyleE_{a}} istheappliedvoltage, E N {\displaystyleE_{N}} istheNernstpotential, R e {\displaystyleR_{e}} and R i {\displaystyleR_{i}} aretheoverallelectronicandionicareaspecificresistancesrespectively,and ϕ O x {\displaystyle\phi^{Ox}} and ϕ a {\displaystyle\phi^{a}} aretheelectricpotentialsattheanodesurfaceandtheanodeelectrolyteinterfacerespectively.[25] Inelectrolysismode ϕ O x {\displaystyle\phi^{Ox}} > ϕ a {\displaystyle\phi^{a}} and E a {\displaystyleE_{a}} > E N {\displaystyleE_{N}} .Whether P O 2 a {\displaystyleP_{O2}^{a}} isgreaterthan P O 2 O x {\displaystyleP_{O2}^{Ox}} isdictatedbywhether( ϕ O x {\displaystyle\phi^{Ox}} - ϕ a {\displaystyle\phi^{a}} )or E a r e a R e {\displaystyle{\frac{E_{a}r_{e}^{a}}{R_{e}}}} isgreaterthan ( E a − E N ) r i a R i {\displaystyle{\frac{(E_{a}-E_{N})r_{i}^{a}}{R_{i}}}} .Theinternaloxygenpartialpressureisminimizedbyincreasingtheelectronicresistanceattheanodeinterfaceanddecreasingtheionicresistanceatanodeinterface. Delaminationoftheanodefromtheelectrolyteincreasestheresistanceofthecellandnecessitateshigheroperatingvoltagesinordertomaintainastablecurrent.[26]Higherappliedvoltagesincreasestheinternaloxygenpartialpressure,furtherexacerbatingthedegradation. Applications[edit] SOECshavepossibleapplicationinfuelproduction,carbondioxiderecycling,andchemicalssynthesis.Inadditiontotheproductionofhydrogenandoxygen,anSOECcouldbeusedtocreatesyngasbyelectrolyzingwatervaporandcarbondioxide.[27] Thisconversioncouldbeusefulforenergygenerationandenergystorageapplications. Research[edit] In2014MITsuccessfullytestedadevicesusedinMarsOxygenISRUExperimentonthePerseveranceroverasameanstoproduceoxygenforbothhumansustenanceandliquidoxygenrocketpropellant.[28][29]OnApril2021NASAclaimedithassuccessfullyproduced1gallonofearth-equivalentoxygen(4and5gramsofoxygenonMars)fromCO2intheMarsatmosphere.[30] Operatingconditions[edit] SOECmodulescanoperateinthreedifferentmodes:exothermic,endothermicandthermoneutral.Inexothermicmode,thestacktemperatureincreasesduringoperationduetoheataccumulation,andthisheatisusedforinletgaspreheating.Therefore,anexternalheatsourceisnotneededwhiletheelectricalenergyconsumptionincreases.Intheendothermicstackoperationmode,thereisanincreaseinheatenergyconsumptionandareductioninelectricalenergyconsumptionandhydrogenproductionbecausetheaveragecurrentdensityalsodecreases.Thethirdmodeisthermoneutralinwhichtheheatgeneratedthroughirreversiblelossesisequaltotheheatrequiredbythereaction.Astherearesomethermallosses,anexternalheatsourceisneeded.Thismodeconsumesmoreelectricitythanendothermicoperationmode.[31] Seealso[edit] Glossaryoffuelcellterms Hydrogentechnologies References[edit] ^Zheng,Yun;Wang,Jianchen;Yu,Bo;Zhang,Wenqiang;Chen,Jing;Qiao,Jinli;Zhang,Jiujun(2017)."Areviewofhightemperatureco-electrolysisofHOandCOtoproducesustainablefuelsusingsolidoxideelectrolysiscells(SOECs):advancedmaterialsandtechnology".Chem.Soc.Rev.46(5):1427–1463.doi:10.1039/C6CS00403B.PMID 28165079. ^DurabilityofsolidoxideelectrolysiscellsforhydrogenproductionArchived2009-07-11attheWaybackMachine ^NiM,LeungMKH,LeungDYC,SumathyK.Areviewandrecentdevelopmentsinphotocatalyticwater-splittingusingTiO2forhydrogenproduction.RenewableSustainableEnergyRev2007;11(3):401–25. ^Ni,M.,Leung,M.K.H.,&Leung,D.Y.C.(2008).Technologicaldevelopmentofhydrogenproductionbysolidoxideelectrolyzercell(SOEC).InternationalJournalofHydrogenEnergy,33,2337–2354.doi:10.1016/j.ijhydene.2008.02.048 ^Areversibleplanarsolidoxidefuel-assistedelectrolysiscell ^ElectrolysisofWater ^Canhightemperaturesteamelectrolysisfunctionwithgeothermalheat? 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^Yue,X.,Yan,A.,Zhang,M.,Liu,L.,Dong,Y.,&Cheng,M.(2008).Investigationonscandium-dopedmanganateLa0.8Sr0.2Mn1-xScxO3-cathodeforIntermediateTemperatureSolidOxideFuelCells.JournalofPowerSources,185,691–697.doi:10.1016/j.jpowsour.2008.08.038 ^X.Yang,J.T.S.Irvine,J.Mater.Chem.18(2008)2349–2354. ^Chen,S.,Xie,K.,Dong,D.,Li,H.,Qin,Q.,Zhang,Y.,&Wu,Y.(2015).Acompositecathodebasedonscandium-dopedchromatefordirecthigh-temperaturesteamelectrolysisinasymmetricsolidoxideelectrolyzer.JournalofPowerSources,274,718–729.doi:10.1016/j.jpowsour.2014.10.103 ^W.Wan,S.P.Jiang,SolidStateIonics177(2006)1361–1369. ^K.Chen,N.Ai,S.P.Jiang,J.Electrochem.Soc.157(2010)P89–P94. ^Chauveau,F.,Mougin,J.,Bassat,J.M.,Mauvy,F.,&Grenier,J.C.(2010).Anewanodematerialforsolidoxideelectrolyser:Theneodymiumnickelate.JournalofPowerSources,195,744–749.doi:10.1016/j.jpowsour.2009.08.003 ^IntermediatetemperaturesolidoxideelectrolysiscellusingLaGaO3basedperovskiteelectrolyte ^Solidoxidefuelcells ^SimpleandAttractiveDemonstrationoftheReversibilityofChemicalReactions ^AProposedMethodforHighEfficiencyElectricalEnergyStorageUsingSolidOxideCells ^Courtney,T.N.(2000)MechanicalBehaviorofMaterials.Groveland,IL:WavelandPress ^Virkar,A.V.(2010)."Mechanismofoxygenelectrodedelaminationinsolidoxide electrolyzercells"InternationalJournalofHydrogenEnergy35:9527-9543 ^Virkar,A.V.(2010)."Mechanismofoxygenelectrodedelaminationinsolidoxide electrolyzercells"InternationalJournalofHydrogenEnergy35:9527-9543 ^GazzarriJ.I.,KeslerO.(2007)“Non-destructivedelaminationdetectioninsolidoxidefuelcells”.JournalofPowerSources;167:430-441. ^CeramatecSolidOxideCo-ElectrolysisCellArchived2011-06-08attheWaybackMachine ^"GoingtotheRedPlanet".MITNews|MassachusettsInstituteofTechnology.Retrieved2021-11-26. ^"MITtosendoxygen-creatinginstrumentonMars2020missionbyNASA-WorldNews,Firstpost".Firstpost.2014-08-04.Retrieved2021-11-26. ^Niiler,Eric."NASA'sMOXIEExperimentIsMakingOxygenonMars".Wired.ISSN 1059-1028.Retrieved2021-11-26. ^R.Daneshpour,M.MehrpooyaDesignandoptimizationofacombinedsolarthermophotovoltaicpowergenerationandsolidoxideelectrolyserforhydrogenproductionEnergyConversManage,176(2018),pp.274-286 Externallinks[edit] 2007DOEHydrogenProgramReview RELHY vteFuelcellsByelectrolyte Alkalinefuelcell Moltencarbonatefuelcell Phosphoricacidfuelcell Proton-exchangemembranefuelcell Solidoxidefuelcell Byfuel Direct-ethanolfuelcell Directmethanolfuelcell Formicacidfuelcell Reformedmethanolfuelcell Directcarbonfuelcell Zinc-airbattery Metalhydridefuelcell Directborohydridefuelcell Biofuelcells Enzymaticbiofuelcell Microbialfuelcell Others Blueenergy Electro-galvanicfuelcell Flowbattery Photoelectrochemicalcell Regenerativefuelcell Solidoxideelectrolysercell Unitizedregenerativefuelcell Proton-exchangemembrane Membraneelectrodeassembly MembranelessFuelCells Protonicceramicfuelcell Hydrogen Economy Storage Station 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