Electrodeposition from Ionic Liquids

398 Pages·8.484 MB·English

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ElectrodepositionfromIonicLiquids
Editedby
FrankEndres,DouglasMacFarlane,
andAndrewAbbott
i
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Electrodeposition from Ionic Liquids
Edited by
Frank Endres, Douglas MacFarlane,
and Andrew Abbott
WILEY-VCH Verlag GmbH & Co. KGaA
iii
fm January11,2008 10:34 CharCount=0
TheEditors (cid:1) AllbookspublishedbyWiley-VCHare
carefullyproduced.Nevertheless,authors,
Prof.Dr.FrankEndres editors,andpublisherdonotwarrantthe
FacultyofNaturalandMaterialSciences informationcontainedinthesebooks,
ClausthalUniversityofTechnology includingthisbook,tobefreeoferrors.
38678Clausthal-Zellerfeld Readersareadvisedtokeepinmindthat
Germany statements,data,illustrations,procedural
detailsorotheritemsmayinadvertentlybe
Prof.DouglasMacFarlane inaccurate.
SchoolofChemistry
MonashUniversity LibraryofCongressCardNo.:appliedfor
Clayton,Victoria3800
Australia BritishLibraryCataloguing-in-PublicationData
Acataloguerecordforthisbookisavailable
fromtheBritishLibrary.
Prof.Dr.AndrewAbbott Bibliographicinformationpublishedbythe
ChemistryDepartment DeutscheNationalbibliothek
UniversityofLeicester DieDeutscheNationalbibliothekliststhis
LeicesterLE17RH publicationintheDeutscheNational-
UnitedKingdom bibliografie;detailedbibliographicdataare
availableintheInternetathttp://dnb.d-nb.de
(cid:1)c 2008WILEY-VCHVerlagGmbH&Co.
KGaA,Weinheim
Allrightsreserved(includingthoseof
translationintootherlanguages).Nopartof
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ISBN978-3-527-31565-9
iv
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v
Contents
Preface IX
Foreword XIII
ListofContributors XV
ListofAbbreviations XIX
1 WhyuseIonicLiquidsforElectrodeposition? 1
AndrewP.Abbott,IanDalrymple,FrankEndres,andDouglasR.MacFarlane
1.1 Non-aqueousSolutions 3
1.2 IonicFluids 3
1.3 WhatisanIonicLiquid? 4
1.4 TechnologicalPotentialofIonicLiquids 6
1.5 ConcludingRemarks 12
References 12
2 SynthesisofIonicLiquids 15
TomBeyersdorff,ThomasJ.S.Schubert,UrsWelz-Biermann,WillPitner,
AndrewP.Abbott,KatyJ.McKenzie,andKarlS.Ryder
2.1 SynthesisofChloroaluminateIonicLiquids 15
2.2 Air-andWater-stableIonicLiquids 21
2.3 Eutectic-basedIonicLiquids 31
References 42
3 PhysicalPropertiesofIonicLiquidsforElectrochemicalApplications 47
HiroyukiOhno
3.1 Introduction 47
3.2 ThermalProperties 47
3.3 Viscosity 54
3.4 Density 55
3.5 RefractiveIndex 56
3.6 Polarity 58
3.7 SolubilityofMetalSalts 64
ElectrodepositionfromIonicLiquids.EditedbyF.Endres,D.MacFarlane,A.Abbott
Copyright(cid:1)C 2008WILEY-VCHVerlagGmbH&Co.KGaA,Weinheim
ISBN:978-3-527-31565-9
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vi Contents
3.8 ElectrochemicalProperties 66
3.9 ConclusionandFutureProspects 77
Acknowledgement 77
References 78
4 ElectrodepositionofMetals 83
ThomasSchubert,SherifZein,ElAbedin,AndrewP.Abbott,
KatyJ.McKenzie,KarlS.Ryder,andFrankEndres
4.1 ElectrodepositioninAlCl -basedIonicLiquids 84
3
4.2 ElectrodepositionofMetalsinAir-andWater-stableIonicLiquids 92
4.3 DepositionofMetalsfromNon-chloroaluminateEutectic
Mixtures 103
4.4 TroublesomeAspects 114
References 120
5 ElectrodepositionofAlloys 125
I.-WenSun,andPo-YuChen
5.1 Introduction 125
5.2 ElectrodepositionofAl-containingAlloysfromChloroaluminate
IonicLiquids 126
5.3 ElectrodepositionofZn-containingAlloysfromChlorozincate
IonicLiquids 132
5.4 FabricationofaPorousMetalSurfacebyElectrochemicalAlloying
andDe-alloying 137
5.5 Nb–Sn 139
5.6 Air-andWater-stableIonicLiquids 140
5.7 Summary 145
References 145
6 ElectrodepositionofSemiconductorsinIonicLiquids 147
NataliaBorisenko,SherifZeinElAbedin,andFrankEndres
6.1 Introduction 147
6.2 GalliumArsenide 149
6.3 IndiumAntimonide 149
6.4 AluminumAntimonide 150
6.5 ZincTelluride 150
6.6 CadmiumTelluride 151
6.7 Germanium 151
6.8 Silicon 155
6.9 GreySelenium 160
6.10 Conclusions 164
References 164
7 ConductingPolymers 167
JenniferM.Pringle,MariaForsyth,andDouglasR.MacFarlane
7.1 Introduction 167
7.2 Electropolymerization–GeneralExperimentalTechniques 171
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Contents vii
7.3 SynthesisofConductingPolymers 177
7.4 Characterization 191
7.5 FutureDirections 203
7.6 Conclusions 207
References 208
8 NanostructuredMetalsandAlloysDepositedfromIonicLiquids 213
RolfHempelmann,andHaraldNatter
8.1 Introduction 213
8.2 PulsedElectrodepositionfromAqueousElectrolytes 215
8.3 SpecialFeaturesofIonicLiquidsasElectrolytes 220
8.4 NanocrystallineMetalsandAlloysfromChlorometallate-based
IonicLiquids 222
8.5 NanocrystallineMetalsfromAir-andWater-stableIonicLiquids 227
8.6 ConclusionandOutlook 234
Acknowledgement 235
References 235
9 ElectrodepositionontheNanometerScale:InSituScanning
TunnelingMicroscopy 239
FrankEndres,andSherifZeinElAbedin
9.1 Introduction 239
9.2 InsituSTMin[Py1,4]TFSA 241
9.3 ElectrodepositionofAluminum 245
9.4 ElectrodepositionofTantalum 250
9.5 ElectrodepositionofPoly(p-phenylene) 252
9.6 Summary 256
References 256
10 PlasmaElectrochemistrywithIonicLiquids 259
Ju¨rgenJanek,MarcusRohnke,ManuelPo¨lleth,andSebastianA.Meiss
10.1 Introduction 259
10.2 ConceptsandPrinciples 260
10.3 EarlyStudies 265
10.4 TheStabilityofIonicLiquidsinPlasmaExperiments 269
10.5 PlasmaElectrochemicalMetalDepositioninIonicLiquids 274
10.6 ConclusionsandOutlook 282
Acknowledgement 283
References 283
11 TechnicalAspects 287
DebbieS.Silvester,EmmaI.Rogers,RichardG.Compton,KatyJ.McKenzie,
KarlS.Ryder,FrankEndres,DouglasMacFarlane,andAndrewP.Abbott
11.1 MetalDissolutionProcesses/CounterElectrodeReactions 287
11.2 ReferenceElectrodesforUseinRoom-temperatureIonicLiquids 296
11.3 ProcessScaleUp 310
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viii Contents
11.4 TowardsRegenerationandReuseofIonicLiquidsinElectroplating 319
11.5 Impurities 334
Appendix:ProtocolfortheDepositionofZincfromaTypeIII
IonicLiquid 344
References 345
12 PlatingProtocols 353
FrankEndres,SherifZeinElAbedin,Q.Liu,DouglasR.MacFarlane,
KarlS.Ryder,andAndrewP.Abbott
12.1 ElectrodepositionofAlfrom1-Ethyl-3-methylimidazolium
chloride/AlCl 353
3
12.2 ElectrodepositionofAlfrom1-Butyl-3-methylimidazolium
chloride–AlCl –Toluene 356
3
12.3 ElectrodepositionofAlfrom1-Ethyl-3-methylimidazolium
bis(trifluoromethylsulfonyl)amide/AlCl 358
3
12.4 ElectrodepositionofAlfrom1-Butyl-1-methylpyrrolidinium
bis(trifluoromethylsulfonyl)amide/AlCl 360
3
12.5 ElectrodepositionofLifrom1-Butyl-1-methylpyrrolidinium
bis(trifluoromethylsulfonyl)amide/Lithium
bis(trifluoromethylsulfonyl)amide 362
12.6 ElectrodepositionofTafrom1-Butyl-1-methylpyrrolidinium
bis(trifluoromethylsulfonyl)amide 364
12.7 ElectrodepositionofZincCoatingsfromaCholineChloride:
EthyleneGlycol-basedDeepEutecticSolvent 365
References 367
13 FutureDirectionsandChallenges 369
FrankEndres,AndrewP.Abbott,andDouglasMacFarlane
13.1 Impurities 369
13.2 CounterElectrodes/Compartments 370
13.3 IonicLiquidsforReactive(Nano-)materials 371
13.4 Nanomaterials/Nanoparticles 372
13.5 Cation/AnionEffects 373
13.6 PolymersforBatteriesandSolarCells 373
13.7 VariableTemperatureStudies 374
13.8 IntrinsicProcessSafety 374
13.9 Economics(Price,Recycling) 375
13.10 WhichLiquidtoStartWith? 375
13.11 FundamentalKnowledgeGaps 376
SubjectIndex 379
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ix
Preface
Aroundtenyearsagotherewereonlyabouttwentypapersperyeardealingwith
“ionicliquids”or“room-temperaturemoltensalts”.Hencetheterm“ionicliquid”
was unknown to most of the scientific community at that time. Furthermore,
therewaspracticallynoknowledgeofitinindustry,andjustahandfulofgroups
worldwide were investigating ionic liquids. Ionic liquids were perceived as an
academic curiosity. When one of us (F.E.) started his independent research in
1996 with the subject “room-temperature molten salts” many people cautioned
himabouttheeccentrictopic.Whatwasthereasonfortheseopinions?Fromthe
1950stoabout1995mostofthepeopleinthecommunityperformedstudieswith
ionic liquids based on AlCl , often called “first generation” ionic liquids. These
3
arehygroscopicliquids,liberatingHClandavarietyofoxo-chloroaluminatesupon
exposure to moisture. Reproducible operation in these liquids requires either a
strictlycontrolledinertgasatmospherewithextremelylowwaterconcentrationor
at least closed vessel conditions with limited contamination. Thus, these liquids
wereconsideredtobedifficulttoworkwithandoflittlepracticalimportance.Onthe
otherhandas“room-temperaturemoltensalts”theyhadattractiveelectrochemical
windowsandallowedtheelectrodepositionofnoblemetalsandofaluminumand
its alloys in micrometer thick layers. Aluminum is quite an interesting metal as
it is self-passivating, thus under air it forms spontaneously an oxide layer which
protectsthemetalunderneathfromfurthercorrosion.
It was John Wilkes who realized that “room-temperature molten salts” would
onlyexperienceawidespreadinterestanduptakeiftheywerestableunderenviron-
mentalconditions.Wilkes’grouppublisheddetailsofthefirstsuchliquidin1992
– –
usingtheBF andthePF anions,thelattershowingamiscibilitygapwithwater.
4 6
Thus these liquids could, in principle, be made water free. (Today we know that
– –
ionicliquidscontainingBF andPF aresubjecttodecompositioninthepresence
4 6
ofwater.)Electrochemicalstudiesshowedthateventhese“early”ionicliquidshad
wideelectrochemicalwindowsofabout4Vwithcathodiclimitsof–2to–2.5V.vs.
NHE.Thiscathodiclimitshould,fromthethermodynamicpointofview,bewide
enoughtoelectrodepositmanyreactiveelements.
Around 1995, Seddon realized that the expression “room-temperature molten
salts”wascounter-productive.Theexpression“moltensalt”wasalwaysassociated
with“hightemperature”,asalsotheeditors(andmanyauthors)ofthisbookhad
ElectrodepositionfromIonicLiquids.EditedbyF.Endres,D.MacFarlane,A.Abbott
Copyright(cid:1)C 2008WILEY-VCHVerlagGmbH&Co.KGaA,Weinheim
ISBN:978-3-527-31565-9
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x Preface
toexperience.Theintroductionoftheterm“ionicliquids”forlowmeltingmolten
saltswithmeltingtemperaturesbelow100◦C(thedefinitionwasactuallycoinedby
Waldenin1914)createdacleardistinctionandthenewterm“ionicliquid”began
toappearinanunprecedentednumberofpublications.Inthelate1990sthefirst
–
papersontheelectrodepositionofsilverandcopperinionicliquidsbasedonBF
4
–
and PF appeared in the literature. From these early papers it was immediately
6
clear that electrodeposition from ionic liquids is not trivial and is actually more
complicatedthanusingionicliquidsbasedonAlCl .Inadditiontoviscosityand
3
conductivityconcerns,impuritiessuchaswater,halidesandorganiccompounds
provedtobemajordifficulties.
Thus,nearlytwentyyearsofaccumulatedknowledgeonAlCl -basedionicliquids
3
couldonlybetransferredwithdifficultytothisnewclassofionicliquids,because
theirLewisacidity/basicitywastotallydifferent.Thus,theelectrochemistryofthese
secondgenerationionicliquidshadtobere-invented,moreorless.Nevertheless,
progresswasnotslowedandin2002alonetherewerealready600papersdealing
with ionic liquids, about 10% concentrating on electrochemical aspects. In the
followingyearsmorestableionicliquidswithwiderelectrochemicalwindowswere
developed and cathodic decomposition potentials as low as –3 V vs. NHE were
reported,openingthedoortotheelectrodepositionofmanyreactiveelementssuch
asSi,Ge,Ta,Al.
Recentlyanovelclassofdeepeutecticsolventsbasedoncholinechloridehave
beendeveloped.Thesecanbehandledeasilyunderenvironmentalconditionsand
circumvent many problems that occur in aqueous solutions. They also offer the
first economically viable liquids that can be used on an industrial scale. As the
interest of electrochemists and classical electroplaters in ionic liquids has risen
stronglyinthelastfewyearswedecided,in2006,tocollectthekeyaspectsofthe
electrodepositionfromionicliquidsinthepresentbook.Thebookhasbeenwritten
by a panel of expert authors during late 2006 and the first half of 2007 and thus
describesthestateoftheartasofthatpointintime.
InChapter1weexplainthemotivationandbasicconceptsofelectrodeposition
fromionicliquids.InChapter2anintroductiontotheprinciplesofionicliquids
synthesisisprovidedasbackgroundforthosewhomaybeusingthesematerialsfor
thefirsttime.Whilemostoftheionicliquidsdiscussedinthisbookareavailable
fromcommercialsourcesitisimportantthatthereaderisawareofthesynthetic
methodssothatimpurityissuesareclearlyunderstood.Nonetheless,sinceacom-
prehensive summary is beyond the scope of this book the reader is referred for
more details to the second edition of Ionic Liquids in Synthesis, edited by Peter
WasserscheidandTomWelton.Chapter3summarizesthephysicalpropertiesof
ionic liquids, and in Chapter 4 selected electrodeposition results are presented.
Chapter4alsohighlightssomeofthetroublesomeaspectsofionicliquiduse.One
mightexpectthatwithadecompositionpotentialdownto–3Vvs.NHEallavailable
elementscouldbedeposited;unfortunately,thesituationisnotassimpleasthat
andthedepositionoftantalumisdiscussedasanexampleoftheissues.InChapters
5 to 7 the electrodeposition of alloys is reviewed, together with the deposition of
semiconductorsandconductingpolymers.Thedepositionofconductingpolymers