EHS-DOC-147_LithiumBatteries.pdfVIP专享VIP免费原创优质

EHS-DOC-147v.21/18LITHIUMBATTERIES1.IntroductionOverthepast20years,lithiumbatterytechnologyhasdramaticallyevolved,providingincreasinglygreaterenergydensity,greaterenergypervolume,longercyclelifeandimprovedreliability.Lithiumisthelightestofallmetals,hasthegreatestelectrochemicalpotentialandprovidesthelargestspecificenergyperweight.Lithiumbatteriesarenowpoweringawiderangeofelectricalandelectronicaldevices,includinglaptopcomputers,mobilephones,powertools,telecommunicationsystemsandnewgenerationsofelectriccarsandvehicles.Nexttoadvantages,newtechnologiesoftenbringnewchallengesandrisks.Reportsonincidentswithlithiumbatteriescatchingfirehavemadethepublicwellawareoftheirflammabilityhazardandhavetriggeredmassiveresearchonthemechanismsinitiatingsucheventsandthewaystomakeoperation,storage,transportationandrecyclingsafer.Thisdocumentcoverssomeofthesafetyrelatedissuesoflithiumbatteries.2.TypesofLithiumBatteries2.1CellorBattery?Althoughtheword"battery"isacommontermtodescribeanelectrochemicalstoragesystem,internationalindustrystandardsdifferentiatebetweena"cell"anda"battery".Acellisasingleencasedelectrochemicalunit(onepositiveandonenegativeelectrode)withavoltagedifferentialacrossitstwoterminals(Figure1).Figure1:ExamplesofcellsAbatteryistwoormorecellsthatareelectricallyconnectedtogetherandfittedwithdevicessuchasacase,terminals,markingandprotectivedevicesthatitneedstofunctionproperly(Figure2).EHS-DOC-147v.22/18Figure2:ExamplesofbatteriesHowever,incommonusage,theterms"cell"and"battery"areusedinterchangeably.Theterm"battery"willbeusedinthisdocument.2.2Lithium-MetalBatteriesLithium-metalbatteries(Figure3)areknownasprimarybatteriesandareusuallynon-rechargeable.Theycontainmetalliclithiumandfeaturehigherchargedensities(longerlife)thanothernon-rechargeablebatteries(e.g.alkalineorzinc-carbon).Themostcommontypeoflithiumbatteriesusemetalliclithiumasanode,manganesedioxideascathodeandasaltoflithiumdissolvedinanorganicsolvent,usuallycomposedofamixtureofahigh-permittivity(e.g.propylenecarbonate)andalow-viscositysolvent(e.g.dimethoxyethane).Figure3:ExamplesoflithiummetalbatteriesHavingalongerlife,lithium-metalbatteriescanreplaceordinaryalkalinebatteriesinmanyconsumerdevices,suchascalculators,pacemakers,remotecarlocks,camerasorwatches.2.3Lithium-IonBatteriesLithium-ion(Li-ion)batteries(Figure4),alsoknownassecondarybatteries,arerechargeablebatteriesinwhichlithiumionsmovefromthenegativeelectrode,usuallymadeofcarbon,tothepositiveelectrodemadeofametaloxide(nickel,manganeseandcobalt)duringdischarge,andbackwhencharging.Theelectrolyteistypicallyamixtureoforganicsolvents,suchasethylenecarbonate,dimethylcarbonateordiethylcarbonate,containingcomplexesoflithiumions,suchaslithiumhexafluorophosphate(LiPF6),EHS-DOC-147v.23/18lithiumhexafluoroarsenatemonohydrate(LiAsF6),lithiumperchlorate(LiClO4),lithiumtetrafluoroborate(LiBF4)orlithiumtriflate(LiCF3SO3).Figure4:Examplesoflithium-ionbatteriesLi-ionbatterieshavehighenergydensity,tinymemoryeffectandlowself-discharge.Theyarecommonlyfoundinhomeandportableelectronics(e.g.laptopcomputers).Theyarealsogrowinginpopularityforbatteryelectricvehiclesoraerospaceapplicationsandarebecomingacommonreplacementformanyapplicationsthathavebeenusinghistoricallyleadacidbatteries.SomeadvantagesofLi-ionbatteriesare:highspecificenergyandhighloadcapabilities;longcycleandextendshelf-life...