用于锂离子电池包热管理的膨胀石墨-相变材料的热力行为

JournalofMaterialsProcessingTechnology210(2010)174-179我们制备了电池热管理模块。模块是由作为相变材料(PCM)的石蜡和石墨片组成。流程是首先将膨胀石墨压缩成所需的模块的形状，然后浸渍到熔化的石蜡。将模块片聚集在一起,接着是得到所需的包装形状。研究了得到的相变材料-膨胀石墨石墨(PCM/EG)复合材料的性质。测试包括导热系数、拉伸压缩和爆破试验。结果表明，在低工作温度下的测试中，随着复合材料中石蜡质量分数的增加，导热系数、抗拉强度、抗压强度和胀破强度提高。相比之下，相对较高的工作温度下的结果却与低温下相反。1Correspondingauthor.Tel.:[phone]x22174;fax:[phone].E-mailaddresses:[e-mail],[e-mail](A.Alrashdan),[e-mail](A.T.Mayyas),[e-mail](S.Al-Hallaj).Thermo-mechanicalbehaviorsoftheexpandedgraphite-phasechangematerialmatrixusedforthermalmanagementofLi-ionbatterypacksAbdallaAlrashdan31,AhmadTurkiMayyas3,SaidAl-HallajbaIndustrialEngineeringDepartment,FacultyofEngineering,JordanUniversityofScienceandTechnology,P.O.Box3030,Irbid22110,JordanbCenterforElectrochemicalScienceandEngineering,DepartmentofChemicalandEnvironmentalEngineering,IllinoisInstituteofTechnology,10West33rdStreet,Chicago,IL60616,USAContentslistsavailableatScienceDirectJournalofMaterialsProcessingTechnologyjournalhomepage::Received31December2008Receivedinrevisedform9June2009Accepted10July2009Keywords:PhasechangematerialThermalconductivityGraphiteMechanicalpropertiesThermalmanagementLi-ionbatteriesInthispaper,blocksforthethermalmanagementofLi-ionbatteryareprepared.Theblocksaremadeofparaffinwax,whichisusedasaphasechangematerial(PCM),andgraphiteflakes.Theprocessstartsbycompactingexpandedgraphiteintothedesiredmodularshapesandthenimpregnatingitintomoltenparaffinwax.Themodularpieceswereassembledtogether,followedbyfinishingoperationstoachieveadesiredpackaginggeometry.Thermo-mechanicalpropertiesoftheproducedphasechangematerial-expandedgraphite(PCM/EG)compositeshavebeenstudied.Thetestsincludethermalconductivity,tensilecompressionandburstingtest.Theresultsshowedthatasmassfractionofparaffinwaxincreasesinthecompositematerial,thethermalconductivity,tensilestrength,compressionstrength,andburststrengthwereimprovedwhiletestedatlowoperatingtemperatures.Incontrast,theresultsshowedreversebehaviorswhentestedatrelativelyhighoperatingtemperature.©2009PublishedbyElsevierB.V.A.Alrashdanetal./JournalofMaterialsProcessingTechnology210(2010)174-1791751.IntroductionThermalenergystoragesystems(TES)havetheabilitytostorehighorlowtemperatureenergyforlateruse(Krupaetal.,2007).Forexample,thesolarenergycanbestoredforovernightheating,thesummerheatstoredforwinteruse,etc.Thus,thesesystemshavepotentialapplicationsinactiveandpassivesolarheating,waterheating,airconditioning,etc.,andareregardedasaneconomicalandsafeenergystoragetechnology.Theideatousephasechangematerials(PCM)forthepurposeofmanagementofthermalenergyistomakeuseofthelatentheatofaphasechange,usuallybetweenthesolidandtheliquidstate.Sinceaphasechangeinvolvesalargeamountoflatentenergyatsmalltemperaturechanges,PCMsareusedfortemperaturestabilizationandforstoringheatwithlargeenergydensitiesincombinationwithrathersmalltemperaturechanges.PassivethermalmanagementusingPCMsissuitableforapplicationswhereheatdissipationisintermittentortransient.Inprinciple,materialsshouldfulfilldifferentcriteriainordertobesuitabletoserveasaPCM(Kandasamyetal.,2007;Krupaetal.,2007;Millsetal.,2006):使用相变材料(PCM)于热能管理的目的是利用相变潜热。由于在很小的温度变化范围内相变涉及大量的潜能，PCM被用于在很小的温度变化范围内维持温度的稳定和储存高密度的热量。使用CPCM的热管理系统适用于间歇性或瞬态散热。原则上,材料应满足不同的标准，以满足作为PCM的需求。如下：合适的熔化温度高熔化焓/体积单位(kJ/m3)高比热(kJ/(kg·K))相变体积变化低高导热系数循环稳定性不易燃无毒无腐蚀在PCM的优点是:高熔化潜热、高能量密度、高比热、可控的温度稳定性,和相变时相变体积小。热量在PCM融化时被储存，在PCM凝固时被释放出来。限定材料的热能存储容量升温物理性质:TheSpecificheatcapacity(cp)比热容；Themeltingpoint(Tm)熔点；Thelatentheatoffusion(Lf)潜热。SuitablemeltingtemperatureHighmeltingenthalpypervolumeunit(kJ/m3)Highspecificheat[kJ/(kgK)]LowvolumechangeduetothephasechangeHighthermalconductivityCyclingstabilityNotflammableNotpoisonousNotcorrosiveAmongtheadvantagesofPCMare:highlatentheatoffusiongivinghighenergydensity,highspecificheat,controllabletemperaturestability,andsmallvolumechangeonphasechange.Heatisstored(withdrawnfromthehotcomponent)duringmeltingandisreleasedtotheambientduringthefreezingperiod(Kandasamyetal.,2007).Someofthephysicalpropertiesthatdeterminethethermalenergystoragecapacityofmaterialsare(Krupaetal.,2007;Kandasamyetal.,2007):•TheSpecificheatcapacity(cp)•Themeltingpoint(Tm)•Thelatentheatoffusion(Lf)Thermalmanagementisrecognizedasoneofthemostsignificantbottlenecksinthedevelopmentofadvancedmicroprocessorsformobileelectronicdevices(LuytandKrupa,2007),suchas176A.Alrashdanetal./JournalofMaterialsProcessingTechnology210(2010)174-179personaldigitalassistants(PDAs),mobilephones,notebooks,digitalcameras,etc.Consideringtheeffectsoftemperatureonthereliabilityoftheelectroniccomponents,thethermaldesignmustbeabletokeeptheworkingtemperatureofsuchdevicesbelowtheirrespectiveallowablemaximumtemperatures(generallyrangingfrom85to1200C)atalltimesduringnormaloperation(Wangetal.,2008).Reliabilityofelectronicpackagesisanotherchallengingfactorinthedesignofmobileelectronicdevices.However,thermalmanagementofLi-ionbatteriesplaysasignificantroleinlargepowerapplicationsinaddre