锂离子电池论文

兰州交通大学毕业设计（论文）I摘要随着电力行业的高速发展，锂离子电池的研究已成为当代的热点研究课题。研究锂离子电池，最主要的是对正极材料的研究，因为锂离子电池由于受到技术制约而使其性能得不到充分发挥。锂离子电池在实际应用中有着循环使用寿命较长、首次充放电比容量高、对环境无污染等优点，已经成为21世纪绿色电源的首选。目前常用的正极材料主要是LiCoO2，由于LiCoO2合成简单，充放电电压平稳，已经广泛用于各个领域，但是LiCoO2中钴材料价格较贵，毒性较大对环境污染严重，实际容量只有理论容量的二分之一，导致它的使用受到严重限制。这就迫使研究者寻找新型的正极材料来代替LiCoO2。LiNi1/3Co1/3Mn1/3O2正极材料价格低，热稳定性高，循环稳定性能良好，是目前高容量电极材料发展的主要方向。本文将采用共沉淀法和溶胶-凝胶法制备锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2，然后利用XRD、SEM、充放电及循环性能测试对其进行结构、形貌研究并测试其电化学性能。共沉淀法制备材料能有效节省材料的制备时间，选择合适的沉淀体系，加入一定量表面活性剂，严格控制反应体系PH在11，配锂量要大于一般的固相反应。当配锂量在1.1时，前驱体经过500℃预处理，然后在850℃下焙烧20h可得到粒径均匀，分散性好的细小颗粒；溶胶-凝胶法制备材料时，通过控制合适的络合剂、易分解的金属离子盐以及反应过程中的温度、时间、PH等条件，找到溶胶-凝胶法制备材料的最佳工艺条件。实验表明，采用适当的反应过程和适宜的PH(6-6.3)值可以得到颗粒细小、均匀且分散性良好的粉状材料，使用这种粉体材料经过500℃预处理，然后在850℃下焙烧20h可以得到粒径在100～300nm，均匀分布的粉末颗粒。首次充放电实验表明，这种材料具有良好的循环稳定性能和较高的容量。关键字：锂离子电池；正极材料；共沉淀；溶胶-凝胶法；LiNi1/3Co1/3Mn1/3O2兰州交通大学毕业设计（论文）IIAbstractWiththehigh-speeddevelopmentofthepowerindustry,theresearchoflithiumionbatteryhasbecomeahotresearchtopicinthecontemporary.Researchonlithiumionbatteries,themostimportantisthestudyoftheanodematerials,becauseofthelithiumionbatteriesduetotechnicalconstraintsandmakenotgivefullplaytoitsperformance.Inactualapplicationoflithiumionbatteryhasafirstchargeanddischargecyclealongservicelife,theadvantagesofhighspecificcapacity,ontheenvironmentpollution-free,hasbecomea21stcenturygreenpowerofchoice.ThepositivematerialsofthecommonlyusedatpresentismainlyLiCoO2,asaresultofLiCoO2synthesisissimple,stablechargeanddischargevoltage,hasbeenwidelyusedineveryfield,butintheLiCoO2cobaltmaterialpriceismoreexpensive,biggertoxicitytoenvironmentpollutionisserious,theactualcapacityisonlyhalfofthetheoryofcapacity,ledtoitsuseislimitedbyserious.ThisforcestheresearcherslookingfornewtoreplacetheLiCoO2cathodematerial.LiNi1/3Co1/3Mn1/3O2cathodematerialpriceislow,highthermalstability,stablecycleperformanceisgood,iscurrentlythemaindevelopmentdirectionofhighcapacityelectrodematerials.Thisthesiswillusethecoprecipitationmethodandsol-gelmethodoflithiumionbatterycathodematerialLiNi1/3Co1/3Mn1/3O2,thenusingXRD,SEM,charge-dischargeandcycleperformancetestresearchonthestructure,morphologyandtesttheirelectrochemicalperformance.Coprecipitationpreparationmaterialcaneffectivelysavethepreparationtime,selecttheappropriatesystemofprecipitation,surfaceactiveagentwasaddedinto,strictcontrolofreactionsystemPHin11,withlithiumcontentthanordinarysolidphasereaction.Precursorwhentheamountoflithiumin1.1after500℃preprocessing,andthenroasting20hunder850℃cangetuniformparticlesize,gooddispersiontinyparticles;Sol-gelmethodmaterials,bycontrollingtheappropriatecomplexingagentandmetalionsaltandeasydecompositionreactionconditions,suchastemperature,timeandPHonthefindmaterialoptimumprocessconditionsofsol-gelmethod.ExperimentsshowthattheproperreactionprocessandthesuitablePHvalue(6-6.3)canbeparticlessmall,uniformandgooddispersancypowdermaterials,theuseofthispowdermaterialsafter500℃preprocessing,andthenroasting20hunder850℃cangetgrainsizein100~300nm,uniformdistributionofpowderparticles.Thefirstchargeanddischargeexperimentsshowthatthematerialhasgoodcyclestabilityperformanceandhighercapacity.KeyWords:Lithium-ionbattery,Cathodematerial,Coprecipitation,Sol-Gelmethod,LiNi1/3Co1/3Mn1/3O2兰州交通大学毕业设计（论文）III目录摘要.............................................................................................................................IAbstract.............................................................................................................................II1绪论...........................................................................................................................-1-1.1研究背景........................................................................................................-1-1.2锂离子电池概述............................................................................................-1-1.2.1锂离子电池的发展历程.....................................................................-1-1.2.2锂离子的应用及前景.........................................................................-2-1.2.3锂离子电池的结构和工作原理.........................................................-2-1.2.4锂离子电池的特点.............................................................................-4-1.3锂离子电池正极材料....................................................................................-4-1.3.1氧化镍锂(LiNiO2)正极材料..............................................................-5-1.3.2氧化钴锂(LiCoO2)正极材料..............................................................-5-1.3.3氧化锰锂(LiMnO2)正极材料.............................................................-6-1.3.4橄榄石结构(LiMPO4)正极材料.........................................................-6-1.3.5尖晶石锰酸锂(LiMn2O4)正极材料....................................................-7-2实验条件与测试方法...............................................................................................-8-2.1化学试剂及主要设备....................................................................................-8-2.1.1化学试剂.............................................................................................-8-2.1.2主