不同方法制备的Al2O3包覆LiMn2O4正极材料的电化学性能  

Electrochemical Properties of Al_2O_3-Coated LiMn_2O_4 Cathode Materials Prepared by Different Methods

作　　者：蔡敏[1] 赖飞燕 张晓辉[2] 王红强[2] 李庆余[2] 

机构地区：[1]广西现代职业技术学院资源工程系,广西河池547000 [2]广西师范大学化学与药学学院,广西桂林541004

出　　处：《材料保护》2015年第10期7-9,44,共4页Materials Protection

基　　金：国家自然科学基金(51364004);广西自然科学重点项目(2013GXNSFDA019027);广西自然科学基金(2012GXNSFAA053214)资助

摘　　要：为了探索制备方法对锰酸锂(LiMn_2O_4)正极材料电化学性能的影响,以硝酸铝[Al(NO_3)_3·9H_2O]和锰酸锂为原料,分别通过溶胶-凝胶法、水热法和微乳液法制备了Al_2O_3包覆LiMn_2O_4正极材料。采用X射线衍射仪(XRD)和场发射扫描电镜(SEM)对试样的表面形貌进行了表征,采用充放电和循环寿命测试等方法研究了试样的电化学性能。结果表明:少量的Al_2O_3包覆对LiMn_2O_4材料的晶体结构并没有影响;溶胶-凝胶法制备的Al_2O_3涂层为无序二维纳米状的网络结构,水热法为纳米片状,微乳液法为棉花絮状,且不能完全包覆;包覆后的试样首次放电比容量都有所下降,但其具有较好的循环性能,其中,以溶胶-凝胶法制备的试样在25℃、1 C条件下循环450周,容量保持率为86.53%;55℃,1 C循环200周的容量保持率为85.46%;而纯相LiMn_2O_4在25,55℃条件下的容量保持率仅分别为57.84%,52.88%。LiMn_2O_4 cathode material coated with Al_2O_3 was prepared from Al(NO_3)_3·9H_2O and LiMn_2O_4 by sol-gel method,hydrothermal method and microemulsion method.X- ray diffractometer(XRD) and field emission scanning electron microscope(SEM) were used to investigate the surface morphology,and the electrochemical properties were studied by charge-discharge test and cycle life test.Results showed that small amounts of Al_2O_3 had no effect on crystal structure.The Al_2O_3 coating could not completely cover the LiMn_2O_4materials,and the structures of coatings were 2D nano-wire for the sol-gel method,nano-sheet for hydrothermal method and flocculent for microemulsion method,respectively.The discharge specific capacity of the first cycle of all the coated samples was decreased,while the cycle performance of them changed better.Among these samples,the sample prepared by sol- gel method exhibited excellent cycle stability after 450 cycles at 25 ℃,1 C or 200 cycles at55℃,1C,and the capacity-keeping rates were 86.53%and85.46%,respectively.But,the capacity-keeping rate of the pure LiMn_2O_4 at 25 ℃ or 55 ℃ were 57.84%or 52.88%.

关 键 词：Al2O3包覆层 溶胶一凝胶法 水热法 微乳液法 尖晶石型LiMn2O4正极材料 电化学性能 

分 类 号：TM912[电气工程—电力电子与电力传动]