锂离子电池层状limno2正极材料制备及其改性地研究.pdf

锂离子电池层状LiMn02正极材料的制备及其改性研究摘要本论文在详细评述了锂离子电池及其正极材料研究进展的基础上,选取层状LiMn02为研究对象,对其制备、复合和掺杂改性进行了研究。采用一步固相法,以葡萄糖为碳源,还原氛围中成功地直接由LiOH、Mn02 ;以750℃下热处理Mn02得到的 Mn203为锰源,;同时,采用Mg和Mo元素对LiMn02材料进行掺杂。与以Mn203为锰源合成O-LiMn02相比, ,大大简化了合成工序,缩短了合成周期。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等手段对产物的物相和微观形貌进行了表征;同时通过充放电测试和交流阻抗测试考察了所得样品的电化学性能,利用非原位XRD图谱分析了充放电过程中 LiMn02/Li2Mn03复合材料的物相变化。通过元素分析仪和等离子体原子发射光谱仪分别对LiMn02材料中的含碳量和复合材料中的Li/MnEL值进行了测定。在大量的实验数据的基础上,我们获得了原料配比、反应温度等条件对合成产物的性能影响。结果表明::Mn:C摩尔比为5:4:2,750℃下焙烧12h;样品具有较好的电化学性能,15次循环后,放电容量为122mAh·g~;同时,"-LiMn02的3V 和4V平台不同,,充放电过程中存在部分向 Mn02转变,这种转变对电化学性能有了很大的影响,出现了放电效率大于1 00% 的现象;30次循环后复合材料的放电容量为218 mAh·g~,明显地改进了 O-LiMn02的充放电性能。;通过对合成的部分LiMn02掺杂改性研究,结果显示:掺Mg摩尔百分含量为10%时,20 %以上,电池的循环性能比没有掺Mg样品有明显提高;掺Mo对材料的性能改性没有掺Mg的效果好,但同样摩尔百分含量的掺杂也是有效地提高了循环性能。同时,’对LiMn02/V02(B)复合材料的电化学性能也进行了研究。关键词:锂离子电池; ; 电化学性能; 掺杂;复合 Research on synthesis and modification oflayered LiMn02 cathode materials batteries Abstraet Based on the research and development indetail on lithium。ion battery and lts cathode material,layered LiMn02 was selected as the research object,and its posite and doped were also studied inthisthesis. O-LiMn02 and LiMn02/Li2Mn03 cathode material was essfully synthesized by the reaction ofLiOH and Mn02 directly,using glucose as carbon source under the reductive atmosphere by one step solid phase -LiMn02 cathode material was synthesized by solid-state and hydrothermal method,respectively, using Mn203,posed from Mn02 at750"C,as the manganese , Mg and Mo were doped inLiMn02 pared to the product using Mn203 asmanganese source,the progress ofthe one using glucose ascarbon source can be performed without high-temperature pretreatment of the synthesis process was greatly simplified,and thesynthesis cycle was shortene