Lithium-ionbattery
Thisarticleisaboutrechargeablelithium-ionbatteries.Fordisposableprimarylithiumbatteries,seelithiumbattery.
“Lithium-ion”redirectshere.Forthemetalelement,seeLithium.
Alithium-ionbatteryorLi-ionbatteryisatypeofrechargeablebatteryinwhichlithiumionsmovefromthenegativeelectrodetothepositiveelectrodeduringdischargeandbackwhencharging.Li-ionbatteriesuseanintercalatedlithiumcompoundasoneelectrodema-terial,comparedtothemetalliclithiumusedinanon-rechargeablelithiumbattery.Theelectrolyte,whichal-lowsforionicmovement,andthetwoelectrodesaretheconstituentcomponentsofalithium-ionbatterycell.Lithium-ionbatteriesarecommoninhomeelectronics.Theyareoneofthemostpopulartypesofrechargeablebatteriesforportableelectronics,withahighenergyden-sity,tinymemorye?ect[8]andlowself-discharge.Be-yondconsumerelectronics,LIBsarealsogrowinginpop-ularityformilitary,batteryelectricvehicleandaerospaceapplications.[9]Forexample,lithium-ionbatteriesarebe-comingacommonreplacementfortheleadacidbatteriesthathavebeenusedhistoricallyforgolfcartsandutilityvehicles.Insteadofheavyleadplatesandacidelectrolyte,thetrendistouselightweightlithium-ionbatterypacksthatcanprovidethesamevoltageaslead-acidbatteries,sonomodi?cationtothevehicle’sdrivesystemisre-quired.
Chemistry,performance,costandsafetycharacteristicsvaryacrossLIBtypes.HandheldelectronicsmostlyuseLIBsbasedonlithiumcobaltoxide(LiCoO
2),whicho?ershighenergydensity,butpresentssafetyrisks,especiallywhendamaged.Lithiumironphosphate(LiFePO
4),lithiumionmanganeseoxidebattery(LiMn2O4,Li2MnO
3,orLMO)andlithiumnickelmanganesecobaltoxide(LiNiMnCoO
2orNMC)o?erlowerenergydensity,butlongerlivesandinherentsafety.Suchbatteriesarewidelyusedforelectrictools,medicalequipmentandotherroles.NMCinparticularisaleadingcontenderforautomotiveappli-cations.Lithiumnickelcobaltaluminumoxide(LiNi-CoAlO
2orNCA)andlithiumtitanate(Li4Ti
1
5O
12orLTO)arespecialtydesignsaimedatparticularnicheroles.Thenewlithiumsulfurbatteriespromisethehigh-estperformance-to-weightratio.
Lithium-ionbatteriescanbedangerousundersomecon-ditionsandcanposeasafetyhazardsincethey,unlikeotherrechargeablebatteries,containa?ammableelec-trolyteandarekeptpressurized.Becauseofthis,thetestingstandardsforthesebatteriesaremorestringentthanthoseforacid-electrolytebatteries,requiringbothabroaderrangeoftestconditionsandadditionalbattery-speci?ctests.[10][11]Thisisinresponsetoreportedac-cidentsandfailures,andtherehavebeenbattery-relatedrecallsbysomecompanies.
1Terminology
Seealso:Batterypack
Althoughtheword“battery”isacommontermtode-scribeanelectrochemicalstoragesystem,internationalindustrystandardsdi?erentiatebetweena“cell”anda“battery”.[11][12]A“cell”isabasicelectrochemicalunitthatcontainsthebasiccomponents,suchaselectrodes,separator,andelectrolyte.Inthecaseoflithium-ioncells,thisisthesinglecylindrical,prismaticorpouchunit,thatprovidesanaveragepotentialdi?erenceatitsterminalsof3.7VforLiCoO2and3.3VforLiFePO
4.A“battery”or“batterypack”isacollectionofcellsorcellassemblieswhicharereadyforuse,asitcontainsanappropriatehousing,electricalinterconnections,andpossiblyelectronicstocontrolandprotectthecellsfromfailure.[13][14]Inthisregard,thesimplest“battery”isasinglecellwithperhapsasmallelectroniccircuitforpro-tection.
Inmanycases,distinguishingbetween“cell”and“bat-tery”isnotimportant.However,thisshouldbedonewhendealingwithspeci?capplications,forexample,batteryelectricvehicles,[15]where“battery”mayindi-cateahighvoltagesystemof400V,andnotasinglecell.Theterm“module”isoftenusedasanintermedi-atetopology,withtheunderstandingthatabatterypackismadeofmodules,andmodulesarecomposedofindi-vidualcells.[14][15]
22History
Seealso:Historyofthebattery
2.1Beforecommercial
introduction
Vartalithium-ionbattery,MuseumAutovision,Altlussheim,Ger-many
LithiumbatterieswereproposedbyMStanleyWhitting-ham,nowatBinghamtonUniversity,whileworkingforExxoninthe1970s.[16]Whittinghamusedtitanium(IV)sul?deandlithiummetalastheelectrodes.However,thisrechargeablelithiumbatterycouldneverbemadepractical.Titaniumdisul?dewasapoorchoice,sinceithastobesynthesizedundercompletelysealedconditions.Thisisextremelyexpensive(~$1000perkilofortitaniumdisul?derawmaterialin1970s).Whenexposedtoair,titaniumdisul?dereactstoformhydrogensul?decom-pounds,whichhaveanunpleasantodour.Forthis,andotherreasons,ExxondiscontinueddevelopmentofWhit-tingham’slithium-titaniumdisul?debattery.[17]Batterieswithmetalliclithiumelectrodespresentedsafetyissues,aslithiumisahighlyreactiveelement;itburnsinnormalatmosphericconditionsbecauseofthepresenceofwaterandoxygen.[18]Asaresult,researchmovedtodevelopbatterieswhere,insteadofmetalliclithium,onlylithiumcompoundsarepresent,beingcapableofacceptingandreleasinglithiumions.
Reversibleintercalationingraphite[19][20]andintercala-tionintocathodicoxides[21][22]wasdiscoveredinthe1970sbyJ.O.BesenhardatTUMunich.Besenhardpro-poseditsapplicationinlithiumcells.[23][24]Electrolytedecompositionandsolventco-intercalationintographiteweresevereearlydrawbacksforbatterylife.
?1973–AdamHellerProposesthelithiumthionylchloridebattery,stillusedinimplantedmedicalde-vicesandindefensesystemswheregreaterthana20-yearshelflife,highenergydensity,orextremeoperatingtemperaturesareencountered.[25]
2HISTORY
?1977–SamarBasudemonstratedelectrochemicalintercalationoflithiumingraphiteattheUniversityofPennsylvania.[26][27]ThisledtothedevelopmentofaworkablelithiumintercalatedgraphiteelectrodeatBellLabs(LiC
6)[28]toprovideanalternativetothelithiummetalelectrodebattery.
?1979–Workinginseparategroups,[29][30][31][32][33]atStanfordUni-versityNedA.Godshalletal.,andthefollowingyearin1980atOxfordUniversity,England,JohnGoodenoughandKoichiMizushima,bothdemonstratedarechargeablelithiumcellwithvoltageinthe4Vrangeusinglithiumcobaltoxide(LiCoO
2)asthepositiveelectrodeandlithiummetalasthenegativeelectrode.[34][35]Thisinnovationprovidedthepositiveelectrodematerialthatmadelithiumbatteriescommerciallypossible.LiCoO
2isastablepositiveelectrodematerialwhichactsasadonoroflithiumions,whichmeansthatitcanbeusedwithanegativeelectrodematerialotherthanlithiummetal.Byenablingtheuseofstableandeasy-to-handlenegativeelectrodematerials,LiCoO2openedawholenewrangeofpossibilitiesfornovelrechargeablebatterysystems.Godshalletal.furtheridenti?edin1979,alongwithLiCoO2,thesimilarvalueofternarycompoundlithium-transitionmetal-oxidessuchasthespinelLiMn2O4,Li2MnO3,LiMnO2,LiFeO2,LiFe5O8,andLiFe5O4(andlaterlithium-copper-oxideandlithium-nickel-oxidecathodematerialsin1985)[36][37]?1980–RachidYazamidemonstratedthere-versibleelectrochemicalintercalationoflithiumingraphite.[38][39]Theorganicelectrolytesavailableatthetimewoulddecomposeduringchargingwithagraphitenegativeelectrode,slowingthedevel-opmentofarechargeablelithium/graphitebattery.Yazamiusedasolidelectrolytetodemonstratethatlithiumcouldbereversiblyintercalatedingraphitethroughanelectrochemicalmechanism.(Asof2011,thegraphiteelectrodediscoveredbyYazamiisthemostcommonlyusedelectrodeincommerciallithiumionbatteries).
?1982–[40]Godshalletal.wereawardedtheU.S.PatentontheuseofLiCoO2ascathodesinlithiumbatteries,basedonGodshall’sStanfordUni-versityPh.D.thesisDissertationand1979publica-tions.
?1983–MichaelM.Thackeray,JohnGoodenough,andcoworkersfurtherdevelopedmanganesespinelasapositiveelectrodematerial,afterits1979identi?cationassuchbyGodshalletal.in1979(above).[41]Spinelshowedgreatpromise,givenitslow-cost,goodelectronicandlithiumionconduc-tivity,andthree-dimensionalstructure,whichgives
2.3Price-?xingconspiracy
itgoodstructuralstability.Althoughpureman-ganesespinelfadeswithcycling,thiscanbeover-comewithchemicalmodi?cationofthematerial.[42]Asof2013,manganesespinelwasusedincommer-cialcells.[43]
3
?2002–Yet-MingChiangandhisgroupatMITshowedasubstantialimprovementintheperfor-manceoflithiumbatteriesbyboostingthemate-rial’sconductivitybydopingit[55]withaluminium,niobiumandzirconium.Theexactmechanismcaus-ingtheincreasebecamethesubjectofwidespreaddebate.[56]?2004–Chiangagainincreasedperformancebyuti-lizingiron(III)phosphateparticlesoflessthan100nanometersindiameter.Thisdecreasedparticledensityalmostonehundredfold,increasedtheposi-tiveelectrode’ssurfaceareaandimprovedcapacityandperformance.CommercializationledtoarapidgrowthinthemarketforhighercapacityLIBs,aswellasapatentinfringementbattlebetweenChiangandJohnGoodenough.[56]?2011–lithium-ionbatteriesaccountedfor66%ofallportablesecondary(i.e.,rechargeable)batterysalesinJapan.[57]?2012–JohnGoodenough,RachidYazamiandAkiraYoshinoreceivedthe2012IEEEMedalforEnvironmentalandSafetyTechnologiesfordevel-opingthelithiumionbattery.
?1985–AkiraYoshinoassembledaprototypecellusingcarbonaceousmaterialintowhichlithiumionscouldbeinsertedasoneelectrode,andlithiumcobaltoxide(LiCoO
2),whichisstableinair,astheother.[44]Byusingmaterialswithoutmetalliclithium,safetywasdra-maticallyimproved.LiCoO
2enabledindustrial-scaleproductionandrepresentsthebirthofthecurrentlithium-ionbattery.?1989–JohnGoodenoughandArumugamManthi-ramoftheUniversityofTexasatAustinshowedthatpositiveelectrodescontainingpolyanions,e.g.,sulfates,producehighervoltagesthanoxidesduetotheinductione?ectofthepolyanion.[45]Thereweretwomaintrendsintheresearchanddevel-opmentofelectrodematerialsforlithiumionrecharge-ablebatteries.Onewastheapproachfromthe?eldofelectrochemistrycenteringongraphiteintercalationcompounds,[46]andtheotherwastheapproachfromthe?eldofnewnano-carbonaceousmaterials.[47]
Historydescribedaboveisbasedontheformerstandpoint.Ontheotherhand,intherecentinterviewarti-?2014–commercialbatteriesfromAmpriusCorp.
cleconcerningthe?rststageofscienti?cresearchactivityreached650Wh/L(a20%increase),usingasili-directlyrelatedtotheLIBdevelopments,itisstatedthatconanodeandweredeliveredtocustomers.[58]Thelookingatthemajorstreamsinresearchdevelopment,[48]NationalAcademyofEngineeringrecognizedJohnthenegative-electrodeoftoday’slithiumionrechargeableGoodenough,YoshioNishi,RachidYazamiandbatteryhasitsoriginsinPAS(polyacenicsemiconduc-AkiraYoshinofortheirpioneeringe?ortsinthe
tivematerial)discoveredbyProfessorTokioYamabeand?eld.[59]laterShjzukuniYataatthebeginningof1980’s.[49][50][51]Theseedofthistechnology,furthermore,wasthedis-coveryofconductivepolymersbyProfessorHidekiShi-rakawaandhisgroup,anditcouldalsobeseenashaving2.3Price-?xingconspiracystartedfromthepolyacetylenelithiumionbatterydevel-opedbyMacDiarmidandHeegeretal.[52]Informationcametolightin2011regardingalong-termantitrustviolatingprice-?xingconspiracyamong
theworld’smajorlithium-ionbatterymanufacturersthat
2.2Commercialproductionkeptpricesarti?ciallyhighfrom2000to2011,ac-cordingtoaclassactioncomplaintthatwastentativelyTheperformanceandcapacityoflithium-ionbatteriesin-settledwithoneofthedefendants,Sony,in2016.[60]creasesasdevelopmentprogresses.Thecomplaintprovidedevidencethatparticipantsin-cludedLG,SD,Sanyo,Panasonic,Sony,andHitachi,?1991–SonyandAsahiKaseireleasedthe?rstcom-andnotesthatSanyoandLGhad“pledguiltytothe
criminalprice-?xingofLithiumIonBatteries.”[60]p.merciallithium-ionbattery.[53]
Sonyagreedtosettlefor$20million,andalsocoop-?1996–JohnGoodenough,AkshayaPadhianderateby,amongotherthings,makingemployeescho-coworkersproposedlithiumironphosphatesenbyplainti?savailableforinterviews,depositionsand(LiFePOtestimony,aswellasprovideclarifyinginformationre-4)andotherphospho-olivines(lithiummetalphos-gardingtheschemeandthedocumentsprovidedtodate,phateswiththesamestructureasmineralolivine)includingrespondingtoauthenticationandclari?cationaspositiveelectrodematerials.[54]questions.[61]Cooperationclause:page23-25.
43
Gigafactory
An18650sizelithiumionbattery,withanalkalineAAforscale.
18650areusedforexampleinnotebooksorTeslaModelS
Theelectrolyteistypicallyamixtureoforganiccarbon-
atessuchasethylenecarbonateordiethylcarbonatecon-
Lithium-ionbatterymonitoringelectronics(over-anddischargetainingcomplexesoflithiumions.[65]Thesenon-aqueousprotection)electrolytesgenerallyusenon-coordinatinganionsalts
suchaslithiumhexa?uorophosphate(LiPF
6),lithiumhexa?uoroarsenatemonohydrate(LiAsF3Construction6),lithiumperchlorate(LiClO
4),lithiumtetra?uoroborate(LiBF
Thethreeprimaryfunctionalcomponentsofalithium-4)andlithiumtri?ate(LiCFionbatteryarethepositiveandnegativeelectrodesand3SO
electrolyte.Generally,thenegativeelectrodeofacon-3).ventionallithium-ioncellismadefromcarbon.Thepos-
itiveelectrodeisametaloxide,andtheelectrolyteisaDependingonmaterialschoices,thevoltage,energylithiumsaltinanorganicsolvent.[62]Theelectrochemicaldensity,lifeandsafetyofalithium-ionbatterycanrolesoftheelectrodesreversebetweenanodeandcath-changedramatically.Recently,novelarchitecturesusingode,dependingonthedirectionofcurrent?owthroughnanotechnologyhavebeenemployedtoimproveperfor-
mance.thecell.
ThemostcommerciallypopularnegativeelectrodeisPurelithiumishighlyreactive.Itreactsvigorouslywithgraphite.Thepositiveelectrodeisgenerallyoneofthreewatertoformlithiumhydroxideandhydrogengas.Thus,materials:alayeredoxide(suchaslithiumcobaltox-anon-aqueouselectrolyteistypicallyused,andasealedide),apolyanion(suchaslithiumironphosphate)oracontainerrigidlyexcludesmoisturefromthebatterypack.spinel(suchaslithiummanganeseoxide).[63]Recently,
graphenebasedelectrodes(basedon2Dand3Dstruc-
turesofgraphene)havealsobeenusedaselectrodesfor
lithiumbatteries.
[64]Lithium-ionbatteriesaremoreexpensivethanNiCdbat-teriesbutoperateoverawidertemperaturerangewithhigherenergydensities.Theyrequireaprotectivecircuittolimitpeakvoltage.
5
Fornotebooksorlaptops,lithium-ioncellsaresuppliedaspartofabatterypackwithtemperaturesensors,voltageconverter/regulatorcircuit,voltagetap,batterychargestatemonitorandthemainconnector.Thesecomponentsmonitorthestateofchargeandcurrentinandoutofeachcell,capacitiesofeachindividualcell(drasticchangecanleadtoreversepolaritieswhichisdangerous),[66]tem-peratureofeachcellandminimizetheriskofshortcir-cuits.[67]
thecathodeoranodematerialinanaqueousororganicsolution.[70]
In2014,PanasoniccreatedthesmallestLi-ionbattery.Itispinshaped.Ithasadiameterof3.5mmandaweightof0.6g.[71]
4Electrochemistry
Theparticipantsintheelectrochemicalreactionsinalithium-ionbatteryarethenegativeandpositiveelectrodeswiththeelectrolyteprovidingaconductiveSeealso:Lithiumpolymerbattery
Li-ioncells(asdistinctfromentirebatteries)are
avail-mediumforlithiumionstomovebetweentheelectrodes.
Bothelectrodesallowlithiumionstomoveinandoutoftheirinteriors.Duringinsertion(orintercalation)ionsmoveintotheelectrode.Duringthereverseprocess,ex-traction(ordeintercalation),ionsmovebackout.Whenalithium-ionbasedcellisdischarging,thepositivelithiumionmovesfromthenegativeelectrode(usuallygraphite="C6"below)andentersthepositiveelectrode(lithiumcontainingcompound).Whenthecellischarging,there-verseoccurs.
3.1Shapes
NissanLeaf'slithium-ionbatterypack.
ableinvariousshapes,whichcangenerallybedivided
Thecathode(marked+)half-reactionis:[72]intofourgroups:[68]
Li1?xCoO2+xLi++xe??LiCoO2
?Smallcylindrical(solidbodywithoutterminals,suchTheanode(marked-)halfreactionis:asthoseusedinlaptopbatteries)
xLiC6?xLi++xe?+xC6
?Largecylindrical(solidbodywithlargethreadedter-Theoverallreactionhasitslimits.Overdischargesuper-minals)saturateslithiumcobaltoxide,leadingtotheproduction
[73]
?Pouch(soft,?atbody,suchasthoseusedincelloflithiumoxide,possiblybythefollowingirreversible
reaction:phones)
Li++e?+LiCoO2→Li2O+CoO
?Prismatic(semi-hardplasticcasewithlarge
threadedterminals,suchasvehicles’tractionpacks)Overchargeupto5.2voltsleadstothesynthesisof
cobalt(IV)oxide,asevidencedbyx-raydi?raction:[74]
Usefulworkisperformedwhenelectrons?owthroughaclosedexternalcircuit.Thefollowingequationsshowoneexampleofthechemistry,inunitsofmoles,makingitpossibletousecoe?cientx.
Cellswithacylindricalshapearemadeinacharacteristic"swissroll"manner(knownasa“jellyroll”intheUS),whichmeansitisasinglelongsandwichofpositiveelec-trode,separator,negativeelectrodeandseparatorrolledintoasinglespool.Themaindisadvantageofthismethodofconstructionisthatthecellwillhaveahigherseriesin-ductance.
Theabsenceofacasegivespouchcellsthehighestgravi-metricenergydensity;however,formanypracticalap-plicationstheystillrequireanexternalmeansofcon-tainmenttopreventexpansionwhentheirstate-of-charge(SOC)levelishigh,[69]andforgeneralstructuralstabilityofthebatterypackofwhichtheyarepart.
LiCoO2→Li++CoO2+e?
Inalithium-ionbatterythelithiumionsaretransportedtoandfromthepositiveornegativeelectrodesbyoxidizingthetransitionmetal,cobalt(Co),inLi1-xCoO2fromCo3+toCo4+
duringcharge,andreducedfromCo4+toCo3+
duringdischarge.Thecobaltelectrodereactionisonlyreversibleforx<0.5,limitingthedepthofdischargeal-lowable.ThischemistrywasusedintheLi-ioncellsde-velopedbySonyin1990.
Since2011,severalresearchgroupshaveannouncedThecell’senergyisequaltothevoltagetimesthecharge.demonstrationsoflithium-ion?owbatteriesthatsuspendEachgramoflithiumrepresentsFaraday’sconstant/6.941
6
or13,901coulombs.At3V,thisgives41.7kJpergramoflithium,or11.6kWhperkg.Thisisabitmorethantheheatofcombustionofgasoline,butdoesnotconsidertheothermaterialsthatgointoalithiumbatteryandthatmakelithiumbatteriesmanytimesheavierperunitofen-ergy.
5CHARGEANDDISCHARGE
5Chargeanddischarge
Duringdischarge,lithiumions(Li+
)carrythecurrentwithinthebatteryfromthenega-tivetothepositiveelectrode,throughthenon-aqueouselectrolyteandseparatordiaphragm.[83]
Duringcharging,anexternalelectricalpowersource(thechargingcircuit)appliesanover-voltage(ahighervoltagethanthebatteryproduces,ofthesamepolarity),forcingachargingcurrentto?owwithinthebatteryfromthepos-itivetothenegativeelectrode,i.e.inthereversedirec-tionofadischargecurrentundernormalconditions.Thelithiumionsthenmigratefromthepositivetothenegativeelectrode,wheretheybecomeembeddedintheporouselectrodematerialinaprocessknownasintercalation.
4.1Electrolytes
ThecellvoltagesgivenintheElectrochemistrysectionarelargerthanthepotentialatwhichaqueoussolutionswillelectrolyze.5.1
Procedure
Liquidelectrolytesinlithium-ionbatteriesconsistof
ThechargingproceduresforsingleLi-ioncells,andcom-lithiumsalts,suchasLiPF
pleteLi-ionbatteries,areslightlydi?erent.
6,LiBF4orLiClO
?AsingleLi-ioncellischargedintwostages:[66]
4inanorganicsolvent,suchasethylenecarbonate,dimethylcarbonate,anddiethylcarbonate.[75]Aliquid
1.Constantcurrent(CC)electrolyteactsasaconductivepathwayforthemovement
ofcationspassingfromthepositivetothenegativeelec-2.Voltagesource(CV)
trodesduringdischarge.Typicalconductivitiesofliquidelectrolyteatroomtemperature(20°C(68°F))arein
?ALi-ionbattery(asetofLi-ioncellsinseries)is
therangeof10mS/cm,increasingbyapproximately30–
chargedinthreestages:
40%at40°C(104°F)anddecreasingslightlyat0°C(32°F).[76]
1.Constantcurrent
Thecombinationoflinearandcycliccarbonates(e.g.,
2.Balance(notrequiredonceabatteryisbalanced)ethylenecarbonate(EC)anddimethylcarbonate(DMC))
o?ershighconductivityandSEI-formingability.Amix-3.Voltagesource
tureofahighionicconductivityandlowviscositycar-bonatesolventsisneeded,becausethetwopropertiesare
Duringtheconstantcurrentphase,thechargerappliesmutuallyexclusiveinasinglematerial.[77]
aconstantcurrenttothebatteryatasteadilyincreasing
Organicsolventseasilydecomposeonthenegativeelec-voltage,untilthevoltagelimitpercellisreached.trodesduringcharge.Whenappropriateorganicsolvents
areusedastheelectrolyte,thesolventdecomposesonini-Duringthebalancephase,thechargerreducesthecharg-tialchargingandformsasolidlayercalledthesolidelec-ingcurrent(orcyclesthechargingonando?toreducetrolyteinterphase(SEI),[78]whichiselectricallyinsulat-theaveragecurrent)whilethestateofchargeofindivid-ingyetprovidessigni?cantionicconductivity.Theinter-ualcellsisbroughttothesamelevelbyabalancingcircuit,
untilthebatteryisbalanced.Somefastchargersskipthis
phasepreventsfurtherdecompositionoftheelectrolyte
afterthesecondcharge.Forexample,ethylenecarbon-stage.Somechargersaccomplishthebalancebycharging
eachcellindependently.
ateisdecomposedatarelativelyhighvoltage,0.7Vvs.lithium,andformsadenseandstableinterface.[79]Duringtheconstantvoltagephase,thechargerappliesaCompositeelectrolytesbasedonPOEvoltageequaltothemaximumcellvoltagetimesthenum-(poly(oxyethylene))providearelativelystableberofcellsinseriestothebattery,asthecurrentgrad-interface.[80][81]Itcanbeeithersolid(highmolecu-uallydeclinestowards0,untilthecurrentisbelowasetlarweight)andbeappliedindryLi-polymercells,orthresholdofabout3%ofinitialconstantchargecurrent.liquid(lowmolecularweight)andbeappliedinregularPeriodictoppingchargeaboutonceper500hours.TopLi-ioncells.chargingisrecommendedtobeinitiatedwhenvoltageRoomtemperatureionicliquids(RTILs)areanotherap-goesbelow4.05V/cell.
proachtolimitingthe?ammabilityandvolatilityofor-Failuretofollowcurrentandvoltagelimitationscanresultganicelectrolytes.[82]inanexplosion.[84]
7
Becauselithium-ionbatteriescanhaveavarietyofposi-tiveandnegativeelectrodematerials,theenergydensity
ChargingtemperaturelimitsforLi-ionarestricterthanandvoltagevaryaccordingly.theoperatinglimits.Lithium-ionchemistryperforms
Theopencircuitvoltageishigherthanaqueousbatter-wellatelevatedtemperaturesbutprolongedexposureto
ies(suchasleadacid,nickel-metalhydrideandnickel-heatreducesbatterylife.
cadmium).[91]Internalresistanceincreaseswithbothcy-Li?ionbatterieso?ergoodchargingperformanceatclingandage.[91][92]Risinginternalresistancecausesthecoolertemperaturesandmayevenallow'fast-charging'voltageattheterminalstodropunderload,whichreduceswithinatemperaturerangeof5to45°C(41to113themaximumcurrentdraw.Eventuallyincreasingresis-°F).[85]Chargingshouldbeperformedwithinthistem-tancemeansthatthebatterycannolongeroperateforanperaturerange.Attemperaturesfrom0to5°Ccharg-adequateperiod.ingispossible,butthechargecurrentshouldbereduced.
Batterieswithalithiumironphosphatepositiveand
Duringalow-temperaturechargetheslighttemperature
graphitenegativeelectrodeshaveanominalopen-circuit
riseaboveambientduetotheinternalcellresistance
voltageof3.2Vandatypicalchargingvoltageof3.6
isbene?cial.Hightemperaturesduringchargingmay
V.Lithiumnickelmanganesecobalt(NMC)oxidepos-leadtobatterydegradationandchargingattemperatures
itiveswithgraphitenegativeshavea3.7Vnominalvolt-above45°Cwilldegradebatteryperformance,whereas
agewitha4.2Vmaximumwhilecharging.Thecharging
atlowertemperaturestheinternalresistanceofthebat-procedureisperformedatconstantvoltagewithcurrent-terymayincrease,resultinginslowerchargingandthus
limitingcircuitry(i.e.,chargingwithconstantcurrentun-longerchargingtimes.[85]
tilavoltageof4.2Visreachedinthecellandcontinu-Consumer-gradelithium-ionbatteriesshouldnotbeingwithaconstantvoltageapplieduntilthecurrentdropschargedattemperaturesbelow0°C(32°F).Althoughaclosetozero).Typically,thechargeisterminatedat3%batterypackmayappeartobechargingnormally,electro-oftheinitialchargecurrent.Inthepast,lithium-ionbat-platingofmetalliclithiumcanoccuratthenegativeelec-teriescouldnotbefast-chargedandneededatleasttwotrodeduringasubfreezingcharge,andmaynotberemov-hourstofullycharge.Current-generationcellscanbeableevenbyrepeatedcycling.Mostdevicesequippedfullychargedin45minutesorless.In2015researcherswithLi-ionbatteriesdonotallowchargingoutsideof0–demonstratedasmall600mAhcapacitybatterycharged45°Cforsafetyreasons,exceptformobilephonesthatto68percentcapacityintwominutesanda3,000mAhmayallowsomedegreeofchargingwhentheydetectanbatterychargedto48percentcapacityin?veminutes.emergencycallinprogress.[86]Thelatterbatteryhasanenergydensityof620Wh/L.
Thedeviceemployedheteroatomsbondedtographitemoleculesintheanode.[93]
5.2Extremetemperatures
6
Performanceofmanufacturedbatterieshasimprovedovertime.Forexample,from1991to2005theenergy
Industryproducedabout660millioncylindricallithium-capacityperpriceoflithiumionbatteriesimprovedmoreioncellsin2012;the18650sizeisbyfarthemostpopu-thanten-fold,from0.3Whperdollartoover3Whperlarforcylindricalcells.IfTeslameetsitsgoalofshippingdollar.[94]40,000ModelSelectriccarsin2014andifthe85-kWhbattery,whichuses7,104ofthesecells,provesaspopularoverseasasitwasintheU.S.,in2014theModelSalone
8Materialswouldusealmost40percentofglobalcylindricalbattery
production.[87]Productionisgraduallyshiftingtohigher-capacity3,000+mAhcells.Annual?atpolymercellde-Theincreasingdemandforbatterieshasledvendorsand
academicstofocusonimprovingtheenergydensity,mandwasexpectedtoexceed700millionin2013.[88]
operatingtemperature,safety,durability,chargingtime,
In2015costestimatesrangedfrom$300–500/kwh.[89]
outputpower,andcostoflithiumionbatterytechnology.Thefollowingmaterialshavebeenusedincommerciallyavailablecells.Researchintoothermaterialscontinues.
Market
7Performance
?Speci?cenergydensity:100to250W·h/kg(360to900kJ/kg)[90]?Volumetricenergydensity:250to620W·h/L(900to2230J/cm3)[2]?Speci?cpowerdensity:300to1500W/kg(at20secondsand285W·h/L)[1]
Cathodematerialsaregenerallyconstructedoutoftwogeneralmaterials:LiCoO2andLiMn2O
4.Thecobalt-basedmaterialdevelopsapseudotetrahe-dralstructurethatallowsfortwo-dimensionallithiumiondi?usion.[95]Thecobalt-basedcathodesareidealduetotheirhightheoreticalspeci?cheatcapacity,highvolumet-riccapacity,lowself-discharge,highdischargevoltage,
8
andgoodcyclingperformance.Limitationsincludethehighcostofthematerial,slighttoxicity,andlowther-malstability.[96]Themanganese-basedmaterialsadoptacubiccrystallatticesystem,whichallowsforthree-dimensionallithiumiondi?usion.[95]Manganesecath-odesareattractivebecausemanganeseischeaperandlesstoxicthanothermaterialsused.Limitationsincludethetendencyformanganesetodissolveintotheelectrolyteduringcyclingleadingtopoorcyclingstabilityforthecathode.[96]Cobalt-basedcathodesarethemostcommonhoweverothermaterialsarebeginningtobedevelopedtomakecheaperandlesstoxiccathodes.[97]
10SELF-DISCHARGE
andcamcorders,electroniccigarettes,handheldgameconsolesandtorches(?ashlights).
?Powertools:Li-ionbatteriesareusedintoolssuchascordlessdrills,sanders,sawsandavarietyofgardenequipmentincludingwhipper-snippersandhedgetrimmers.
?Electricvehicles:BecauseoftheirlightweightLi-ionbatteriesareusedforpropellingawiderangeofelectricvehiclessuchasaircraft,[116][117][118]electriccars,[119]Pedelecs,hybridvehicles,ad-vancedelectricwheelchairs,radio-controlledmod-els,modelaircraftandtheMarsCuriosityrover.Li-ionbatteriesareusedintelecommunicationsapplica-tions.Secondarynon-aqueouslithiumbatteriesprovidereliablebackuppowertoloadequipmentlocatedinanet-workenvironmentofatypicaltelecommunicationsser-viceprovider.Li-ionbatteriescompliantwithspeci?ctechnicalcriteriaarerecommendedfordeploymentintheOutsidePlant(OSP)atlocationssuchasControlledEn-vironmentalVaults(CEVs),ElectronicEquipmentEn-closures(EEEs),andhuts,andinuncontrolledstructuressuchascabinets.Insuchapplications,li-ionbatteryusersrequiredetailed,battery-speci?chazardousmaterialin-formation,plusappropriate?re-?ghtingprocedures,tomeetregulatoryrequirementsandtoprotectemployeesandsurroundingequipment.[120]
8.18.2
PositiveelectrodeNegativeelectrode
Anodematerialsaregenerallyconstructedfromgraphiteandothercarbonmaterials.Thesematerialsareusedbe-causetheyareabundantandareelectricallyconductingandcanswellmodestlytoaccommodatethelithiumionsassociatedwithbuildingcharge.Siliconisbeginningtobelookedatasananodematerialbecauseitcanswellmuchmorethangraphite,storingupto10timesmorelithiumions,howeverthisswellingcanbreaktheelectri-calcontactsintheanodecausingcatastrophicfailureforthebattery.[107]
8.3Di?usion
10
Self-discharge
Theionsintheelectrolytedi?usebecausetherearesmallchangesintheelectrolyteconcentration.Lineardi?usionisonlyconsideredhere.Thechangeinconcentration,c,asafunctionoftimetanddistancex,is
?c?c
=?DThenegativesignindicatestheionsare?owingfromhighconcentrationtolowconcentration.Inthisequation,Disthedi?usioncoe?cientforthelithiumion.Ithasavalueof7.5×10?10m/sintheLiPF
6electrolyte.Thevalueforε,theporosityoftheelec-trolyte,is0.724.[114]
Alithium-ionbatteryfromalaptopcomputer(176kJ)
9Uses
Li-ionbatteriesprovidelightweight,highenergydensitypowersourcesforavarietyofdevices.Topowerlargerdevices,suchaselectriccars,connectingmanysmallbat-teriesinaparallelcircuitismoree?ective[115]andmoree?cientthanconnectingasinglelargebattery.Suchde-vicesinclude:
?Portabledevices:theseincludemobilephonesandsmartphones,laptopsandtablets,digitalcameras
Batteriesgraduallyself-dischargeevenifnotconnectedanddeliveringcurrent.Li+rechargeablebatterieshaveaself-dischargeratetypicallystatedbymanufacturerstobe1.5-2%permonth.[121][122]Therateincreaseswithtem-peratureandstateofcharge.A2004studyfoundthatformostcyclingconditionsself-dischargewasprimarilytime-dependent;however,afterseveralmonthsofstandonopencircuitor?oatcharge,state-of-chargedepen-dentlossesbecamesigni?cant.Theself-dischargeratedidnotincreasemonotonicallywithstate-of-charge,butdroppedsomewhatatintermediatestatesofcharge.[123]Self-dischargeratesmayincreaseasbatteriesage.[124]
11.2Degradation9
Degradationisstronglytemperature-dependent;increas-ingifstoredorusedathighertemperatures.Highchargelevelsandelevatedtemperatures(whetherfromchargingorambientair)hastencapacityloss.[91]Carbonanodesgenerateheatwheninuse.Batteriesmayberefrigeratedtoreducetemperaturee?ects.[130]
Forcomparison,theself-dischargerateisover30%permonthforcommonnickelmetalhydride(NiMH)batteries,[125]droppingtoabout1.25%permonthforlowself-dischargeNiMHbatteries,and10%permonthinnickel-cadmiumbatteries.
Pouchandcylindricalcelltemperaturesdependlinearly
11Batterylifeonthedischargecurrent.[131]Poorinternalventilation
mayincreasetemperatures.Lossratesvarybytemper-Rechargeablebatterylifeistypicallyde?nedasthenum-ature:6%lossat0°C(32°F),20%at25°C(77°F),andberoffullcharge-dischargecyclesbeforesigni?cantca-35%at40°C(104°F).Incontrast,thecalendarlifeof
LiFePOpacityloss.Storagealsoreducescapacity.
4cellsisnota?ectedbyhighchargestates.[132][133]
Manufacturers’informationtypicallyspecifylifespanin
termsofthenumberofcycles(e.g.,capacitydroppingTheadventoftheSEIlayerimprovedperformance,butlinearlyto80%over500cycles),withnomentionofincreasedvulnerabilitytothermaldegradation.Thelayerchronologicalage.[126]Researchrejectsthiscommonin-iscomposedofelectrolyte–carbonatereductionprod-dustrypractice.Onaverage,lifetimesconsistof1000uctsthatservebothasanionicconductorandelectroniccycles,[127]althoughbatteryperformanceisrarelyspeci-insulator.Itformsonboththeanodeandcathodeandde-?edformorethan500cycles.Thismeansthatbatteriesterminesmanyperformanceparameters.Undertypicalofmobilephones,orotherhand-helddevicesindailyuse,conditions,suchasroomtemperatureandtheabsenceofarenotexpectedtolastlongerthanthreeyears.Somechargee?ectsandcontaminants,afterthe?rstchargethebatteriesbasedoncarbonanodeso?ermorethan10,000layerreachesa?xedthickness,allowingthedevicecan
operateforyears.However,operationoutsidesuchpa-cycles.[128]
rameterscandegradethedeviceviaseveralreactions.[77]
Asabatteryself-discharges,itsvoltagegraduallydimin-ishes.Whendepletedbelowtheprotectioncircuit’slow-voltagethreshold(2.4to2.9V/cell,dependingonchem-11.2.1Reactionsistry)thecircuitdisconnectsandstopsdischarginguntil
recharged.Asdischargeprogresses,metalliccellcon-Fivecommonexothermicdegradationreactionscantentsplateontoitsinternalstructure,creatinganun-occur:[77]wanteddischargepath.
?Chemicalreductionoftheelectrolytebytheanode.
11.1Variability
?Thermaldecompositionoftheelectrolyte.
A2015studybyAndreasGutschoftheKarlsruheInsti-?Chemicaloxidationoftheelectrolytebythecath-tuteofTechnologyfoundthatlithium-ionbatterystor-ode.
agelifetimecouldvarybyafactorof?ve,withsomeLi-ioncellslosing30%oftheircapacityafter1,000cycles,?Thermaldecompositionbythecathodeandanode.andothershavingbettercapacityafter5,000cycles.Thestudyalsofoundthatsafetystandardsforsomebatteries?Internalshortcircuitbychargee?ects.werenotmet.Forstationaryenergystorageitwasesti-matedthatbatterieswithlifespansofatleast3,000cycleswereneededforpro?tableoperation.AnodeTheSEIlayerthatformsontheanodeisamix-tureoflithiumoxide,lithium?uorideandsemicarbonates
(e.g.,lithiumalkylcarbonates).
11.2Degradation
Overtheirlifespan,batteriesdegradeprogressivelywithreducedcapacity,cyclelife,andsafetyduetochemicalchangestotheelectrodes.Capacityloss/fadeisexpr
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