文档介绍：中文摘要
目前市售的锂离子电池正极材料主要采用层状LiC002。由于钴资源的短缺、 LiC002材料在大电流充放电和高温环境使用的不安全等因素,研究开发新一代高性能正极材料成为一项重要课题。尖晶石型LiMn204材料具有原料来源广泛、生产成本低和环境友好等优点,特别是因为充放电电压高、循环性能好、比容量较高和使用安全等优良的电化学性能,该材料已成为锂离子电池正极材料研究的重点。但该材料存在高温容量衰减快、高温性能不理想等缺点。为了改善其性能,本文通过改进该材料的合成方法,制备出性能优异的钴和镧掺杂富锂型球形锰酸锂材料,并对材料的结构、表面形貌和电化学性能进行了研究。
本论文首先采用控制结晶法制备了球形碳酸盐型前躯体材料,经过对比研究得出最优化的制备工艺:沉淀剂为NI-14HC03:反应物浓度分别为:盐溶液
=2mol/L,h=2tool/L;加入方式为采用蠕动泵并加;反应时间为4h,搅拌强度为300r/min,陈化时间为1h,反应体系温度为150C。在该最佳工艺条件下制备的球形前躯体的振实密度可达1,Sg/gm3。同时,在该条件下制备的前躯体球形度好、晶体结构致密、粒径分布均匀。
以上述制备的球形碳酸盐为前躯体制备得到了Co和La掺杂的球形富锂型锰酸锂材料。 oC的焙烧温度范围内,随着焙烧温度升高,X射线衍射(XRD)结果表明,合成材料为单相,材料结晶度上升;扫描电镜(SEM)结果
表明,材料粒径增大,比表面减小。钴和镧共掺杂的富锂型锰酸锂材料具有较小的极化电阻,在800 oC焙烧的Li]., l %。电池实效性能测试结果表明, 掺杂后的材料具有良好的高温性能,450C循环400次后容量保持率大于82%。
关键词:锂离子电池;锰酸锂;钴掺杂;镧掺杂;电化学性能
Abstract
Presently,most of the cathode materials in the lithium ion batteries on the market a∞layered lithium ,the limitation of the cobalt resources and the unsafe factors under hi曲current and/or hi【gh temperature make the R&D of the novd cathode materials an important spinal LiMn204
material became one of the research foei of the cathode materials of the lithjum ion batteries due to its abundance raw material resources,low product cost,envkonment friendly nature,especially high charge/discharge voltage,good cycle ability, considerable specific capacity and good ,the ings of
the material,for example,fast capacity fade,poor high temperature performance,etc.
order to improve the performance of the material,the cobalt and lanthanum doped lithium-rich spherical lithium manganate material谢血good performance was prepared by means of a novel synthesis method in this structure,the Sul'faoe configuration and the electrochemical properties were also smdied.
In this work,crystallization con血oged co-precipitation was employed for the preparation of the m舳ganese earbonate pl'∞RI"SOL After researeh parison,a