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题名: 锰酸锂的微波合成以及球形化制备研究
作者: 崔涛
答辩日期: 2008-06
导师: 康雪雅
专业: 材料物理与化学
授予单位: 中国科学院研究生院
授予地点: 北京
学位: 硕士
关键词: 锂离子电池 ; 流变相辅助微波合成法 ; 改性锰酸锂 ; 电化学性能 ; 球形锰酸锂 ; 乳液法 ; 二次造粒
摘要: 锂离子电池与传统的二次电池如铅酸电池、Ni/Cd 电池、Ni/MH 电池等相比,在比功率、能量密度及充放电性能方面有着明显的优势。而且,锂离子电池还有着循环寿命长、自放电率低、“绿色”环保等优点,目前已广泛地应用于小型电器中,并正积极地向国防工业、空间技术、电动汽车、静置式备用电源 (UPS)等领域发展。锂离子电池技术及性能的进一步提高,主要依赖于电池中各组分材料的改进开发及电池工艺的革新,进一步提高性能和降低成本是现阶段锂离子电池发展和改进的主攻方向。本论文综述了当前锂离子电池电极材料最新研究进展,通过流变相辅助微波法合成改性的动力锂离子电池正极材料尖晶石型锰酸锂材料,并在此基础上开展了乳液法二次造粒研究。利用XRD、SEM 和激光粒度仪等技术对电极材料的微观结构和形貌、粒度进行了分析,采用恒电流充放电技术测试了其电化学性能:1.对掺杂Al 的改性LiMn2O4 正极材料的制备方法进行了详细的研究并加以改进,采用流变相辅助微波法制备了改性尖晶石型LiMn2O4 锂离子电池正极材料。实验结果表明,流变相辅助微波法具有焙烧反应时间短,节约能源等优点,且制得的LiMn2O4样品形貌规则,颗粒分散均匀。确定了最佳的合成温度和时间:750℃,2h。对其进行了XRD 分析和SEM 研究,并就结构、形貌与传统固相法制备的LiMn2O4、LiAl0.03Mn1.97O4 进行了比较。采用这种流变相辅助微波合成法制备的LiAl0.03Mn1.97O4具有优良的电化学性能,测试结果表明,这种材料具有比较高的首次放电容量(115mAh/g),以及良好的可逆性、优异的循环性能,25 次循环结束比容量几乎不变,保持在115mAh/g 左右,衰减性得到很好的改善。2.介绍了目前锂离子电池正极材料球形化制备的情况,对乳液法二次造粒的方法及其机理进行了初步探讨。以微波合成法制备的LiMn2O4 作为一次颗粒,采用一种特殊乳液法进行二次造粒,初步制备了球形LiMn2O4 正极材料。对二次造粒的产物进行了SEM、XRD 分析,测试了其振实密度和电化学性能,发现在二次造粒过程中一次颗粒有一定生长,二次颗粒球状形貌还不够理想,分析了原因,为进一步研究打下基础。
英文摘要:
1. The preparation of Al-doped spinel LiMn2O4 cathode materials has been studied detailedly, and we have made some improvement. Pure-phase and well-crystallized Al-doped spinel LiMn2O4 powders as a cathode material for lithium-ion battery were successfully synthesized by a new simple rheological-phase-assisted microwave synthesis method. The results of the experiments indicate that the rheological-phase-assisted microwave synthesis method has the advantages of shorter sintering time and energy-saving. The synthesized powders are pure, spinel-structure particles of regular shapes with uniform distribution. The best condition for synthesizing is sintering at 750℃ for 2h. The structure and surface morphology of the as-synthesized samples compared with the pristine LiMn2O4 and LiAl0.03Mn1.97O4 obtained from the traditional solid-state reaction method have been investigated. The powders were used as positive materials for lithium-ion battery, whose charge/discharge properties and cycle performance have been examined in detail. The results reveal that the powders prepared by the rheological-phase-assisted microwave synthesis method exhibit a higher initial discharge capacity of 115mAh/g, much better reversibility and good cycling stability without discharge capacity fading, retaining 115mAh/g around. 2. In this thesis we also introduce research of spherical cathode material used in lithium-ion battery, elaborating a special emulsion method and its mechanism. The primary LiMn2O4 was synthesized by microwave synthesis method, and the secondary particle was prepared by the special emulsion method. The secondary particle was researched by SEM and XRD. Its tap density and electrochemical performance were tested. It was found that the primary LiMn2O4 grew right along during the second sintering, but the morphology was not ideally spherical. The result was analyzed for the further research.
内容类型: 学位论文
URI标识: http://ir.xjipc.cas.cn/handle/365002/3543
Appears in Collections:材料物理与化学研究室_学位论文

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作者单位: 中国科学院新疆理化技术研究所

Recommended Citation:
崔涛. 锰酸锂的微波合成以及球形化制备研究[D]. 北京. 中国科学院研究生院. 2008.
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