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Magnesiumbatteries413●MMMacInnes,DuncanArthur(March,,SaltLakeCity,Utah,USA–Sept.,,Hanover,N.H.,USA)[i]MacInnesgraduatedwithaB.S.degreeinchemicalengineeringfromtheUni-versityofUtahin,anddidhisgraduateworkinelectrochemistryattheUniversityofIllinois.InhemovedtotheMassachusettsInstituteofTechnol-ogyandbecameAssociateProfessorin.InhewasinvitedtojointheRockefellerInstituteasAsso-ciateMember,andinhebecameaMember,apo-sitionthathehelduntilwhenhebecameEmeri-tusMember.MacInnesmadenumerouscontributionstoelectrochemistry,e.g.,experimentallyverifyingtheDebye–Hückeltheoryofelectrolytesolutions[ii],de-velopingalow-resistanceglassforglasselectrodes(theso-calledMacInnes-typeglassorpHCorningGlass:%NaO,%CaO,%SiO)[iii],improvingthemovingboundarymethodtodeterminetransfer-encenumbersofions[iv],studiesonthedependenceoftheacidityconstantsoforganicacidsontheirconstitu-tion[v],andstudiesonliquidjunctionpotentials[vi].MacInnesinventedtheuseofa‘retardedelectrode’fordifferentialpotentiometrictitrations[vii].MacInnesalsowroteaninfluentialtextbook[viii].Refs.:[i]LongsworthLG,ShedlovskyT()JElectrochemSoc:C;[ii]MacInnesDA()JAmChemSoc:;MacInnesDA,CowperthwaiteJA()TransFaradaySoc:;[iii]MacInnesDA,DoleM()IndEngChemAnal:,;MacInnesDA,DoleM()JAmChemSoc:;[iv]MacInnesDA,SmithER()JAmChemSoc:;MacInnesDA,SmithER()JAmChemSoc:;MacInnesDA,BrightonTB()JAmChemSoc:,;MacInnesDA,CowperthwaiteJA,BlanchardKC()JAmChemSoc:;MacInnesDA,CowperthwaiteJA,HuangTC()JAmChemSoc:;[v]MacInnesDA()JAmChemSoc:;[vi]MacInnesDA()JAmChemSoc:;MacInnesDA()ProcNatlAcadSci:;[vii]MacInnesDA,JonesPT()JAmChemSoc:;MacInnesDA,DoleM()JAmChemSoc:;[viii]MacInnesDA()Theprinciplesofelectrochemistry.NewYork(reprinted)FSMacropores(macroporosity)porouselectrodesMadelungconstant—isthefactorbywhichtheionicchargesmustbescaledtocalculatetheelectrostaticin-teractionenergyofanioninacrystallatticewithgivenstructure,andthetotallatticeenergyofioniccrystals.Thisconstantissolelydeterminedbythegeometricalar-rangementofpointcharges,andhasthesamevalueforallcompoundshavingidenticalstructure.Theelectro-staticinteractionenergy,calledoftentheMadelungen-ergy,isthemaincontributiontothetotalbindingenergyoflatticeswithpredominantlyionicbonding.Ref.:[i]KittelC()Introductiontosolidstatephysics,thedn.Wiley,ChichesterVKMagnesiumbatteriesBatteriesthatutilizemetallicmagnesiumasanode.Magnesiumanode-basedbatter-iesbelongtoseveralverydifferentfamiliesofbatter-ies.Allthesebatteriesareaimedtotakeadvantageofthehightheoreticalchargecapacityofmagnesiumanditslowredoxpotentialinordertorealizehighen-ergydensitybatteries.Commercialmagnesiumbatter-iesinclude:i)Aqueousmagnesium–manganeseoxideprimarycells,usedprimarilyformilitaryapplication.Theseexhibithigherenergydensitythenzinc–carboncells(Leclanchécell),withrelativelyflatdischargecurves,excellentshelflifeandgoodpower.Thesebatter-iessufferfromveryrapidself-dischargeafterputtingintoservice.ii)Magnesiumwater-activatedbatteriesbelongtothefamilyofreservebatteries.Thesecomewithavarietyofcathodes,suchasAgCl,CuCl,CuSCN,CuClandMnO.Thesecellscomeinvariousdesigns,eachtargetedatdifferentapplication.Ingeneral,ex-ceptforhighenergydensity,therecellspossessexcep-tionalshelflife,owingtotheirreserve-batterydesign.Additionally,thereareseveralmagnesiumbatteriesthatareexperimental,orinvariousstagesofdevelopment:iii)Magnesium–airbatteriesarealsoaqueous,primarybatteries,buttheseuseoxygenfromtheairforreduc-tionatthecathode.Althoughmuchefforthasbeende-votedfortheirdevelopment,uptodatetheyhavenotbeencommercialized.iv)Magnesium–organicsolvent414Magnesiumelectrochemistry●Mprimarybatteries,thathavebeenproposed,coupledwithavarietyofcathodematerials,amongthem,meta-dinitrobenzene,havereachedanadvanceddevelopmentstage.v)Rechargeablemagnesiumbatteries,basedonorganicsolvents,organo-haloaluminumandmagne-siumcomplexsalts,withMoSchevrelphasecathode.Thesecellsexhibitverylongcyclelifewithmoderateenergydensity.Refs.:[i]CromptonTR()Batteryreferencebook,rdedn.Newnes,Oxford,chap,,,,,,,;[ii]SpellmanPJ,LarsenDM,EkernRJ,OxleyJE()Magnesiumandaluminumcells.In:LindenD()Handbookofbatteries,ndedn.McGraw-Hill,NewYork,pp.–.;[iii]KoontzRA()Magnesiumwater-activatedbatteries.In:LindenD()Handbookofbatteries,ndedn.McGraw-Hill,NewYork,pp.–..[iv]AurbachD,LuZ,SchechterA,GoferY,GizbarH,TurgemanR,CohenY,MoshkovichM,LeviE()Nature:YG,DAMagnesiumelectrochemistry—canconsideredinre-gardtothemediainwhichthemagnesiumelectrodeisincontactwith,i.e.,aqueousornonaqueoussolu-tions,ormoltensalts.Asmagnesiumisoneoftheelectropositive(or“oftheleastnoble”)elements,withredoxpotentialof−.V,themetalreactssponta-neouslywithwater,yieldinghydrogengasandmag-nesiumions.Nevertheless,numerousstudiesinvolvingaqueousmagnesiumelectrochemistryhavebeenpub-lished,andaqueousmagnesiumbatteriesarecommer-ciall