锂离子电池的结构及工作原理分析研究 化学工程专业VIP专享VIP免费

摘要锂离子电池是90年代后投放市场的新一代绿色环保电池，它因为电压高、自放电率低、体积小、重量轻、无记忆效应等独特性能被广泛应用于便携式电器以及电动自行车中。目前商品化的锂离子电池广泛采用的负极材料是石墨类碳材料，但由于碳/石墨第一次充放电时，会在碳表面形成钝化膜，造成容量损失;而且碳的电极电位与锂的电位很接近，当电池过充电时，金属锂可能在碳电极表面析出，形成枝晶而引发安全性问题。而Li4Ti5O12作为锂离子电池负极材料在充放电时结构几乎不发生变化被称为“零应变”材料，具有非常优越的循环性能。钦酸锂具有原料来源广泛、价格低廉、热稳定性好、比能量高、循环性能好、安全性能突出等特点。其理论容量为175mAh/g，工作电压为1.5V左右，是很具潜力的负极材料之一。本文采用溶胶一凝胶法，以草酸和柠檬酸为调节剂，制备出了尖晶石Li4Ti5O12，研究了调节剂与钦酸丁醋的比例和烧结时间对产物电化学性能的影响。结果表明当调节剂草酸与钦酸丁醋的摩尔比为1.0时，在8000C烧结20h的产物粒度为400nm左右，在O.1C倍率下，首次放电比容量为145.9mAh/g30次循环后放电比容量为125.8mAh/g。当调节剂柠檬酸与钦酸丁醋的摩尔比为0.5时，在8500C烧结24h的产物粒度为450nm左右，在O.1C倍率下，首次放电比容量为144.5mAh/g30次循环后放电比容量为125.9mAh/g关键词：锂离子电池，负极材料，溶胶一凝胶法，水热法，Li4Ti5O12AbstractLithiumionbatteryisanewgenerationgreennon-pollutionbatterywhenitwasusedinthe1990s.Itiswidelyusedinportableelectronapparatusandcarsduetoitshighlights,suchashighvoltage,lowdischargeratebyitself,littlevolume,lightweightandnonmemeoryeffect,buttheanodematerialsforlithiumionbatteriesarethekeytoconstrainitswholeperformance.Thenegative-electrodematerialsareusuallycarbonincommerciallithiumionbatteries.Butwhendischargeforthefirsttime,therearepassivationmembraneonthesurfaceofcarbon,whichwillcausecapacitylose.Moreover,thepotentialofcarbonisveryclosetothatoflithium,whenovercharge,themetallithiumwillseparateoutonthesurfaceofcarbon,whichistheintrinsicsafetywemustconcern.While,forLi4Ti5O12whenusedasnegativematerialforLionbattery,thereisnosuchconcerns,andduringtheprocessofLi+intercalationandde-intercalation,itscrystalformdoesnotchangeandthetotalvolumechangeislessthan1%,soitisregardedasa"zerostrain"material.Ithasmanycharacteristics,suchasawiderangeofrawmaterials,lowcost,goodthermalstability,highspecificenergy,goodrecyclingperformanceandoutstandingfeaturessuchassecurity.SoLi4Ti5012,isoneofthemostpotentialanodematerialswhichhasahightheoretioaloapaoity(175mAh/g)andvoltageKeyWords:lithiumionbattery,anodematerials,So1-Gelmethod,hydrothermal目录摘要..............................................................................................................................................IAbstract...........................................................................................................................................II1.课题的目的和意义.....................................................................................................................11.1课题的目的.......................................................................................................................11.2课题的意义.......................................................................................................................12.课题背景.....................................................................................................................................23.文献综述.......................................................................................