Mn含量对正极材料LiMn_xCo_(0.2)Ni_(0.8-x)O_2的结构与电化学性能的影响  

Effects of Manganese Content on the Structure and Electrochemical Performance of LiMn_xCo_(0.2)Ni_(0.8-x)O_2 Cathode Materials

作　　者：姜斌[1] 张永恒[1] 

机构地区：[1]青岛科技大学材料科学与工程学院,山东青岛266042

出　　处：《青岛科技大学学报（自然科学版）》2010年第1期26-31,共6页Journal of Qingdao University of Science and Technology:Natural Science Edition

摘　　要：通过共沉淀法合成了具有层状结构的锂离子电池正极材料LiMnxCo0.2-Ni0.8-xO2。采用XRD、XPS和恒流充放电等测试手段研究了Mn含量变化对正极材料LiMnxCo0.2Ni0.8-xO2的物理性质与电化学性能的影响。结果表明:Mn含量的增加会引起元素O和Ni的氧化态降低,使得Ni由+3价逐渐转变为+2价,而Mn的氧化态却始终保持+4价不变;尽管Mn含量的增加会使材料的充放电比容量有所降低,但是材料的结构稳定性和热稳定性会得到改善。XRD测试结果表明样品LiMnxCo0.2Ni0.8-xO2(0≤x≤0.5)都具有标准的-αNaFeO2层状结构。此外,从Mn含量的变化引起的样品晶胞参数的变化表明,当0≤x≤0.25时LiMnxCo0.2Ni0.8-xO2可能形成的是假固溶体,当Mn含量由0.3增加到0.5时形成的是真固溶体。The layered materials LiMnxCo0.2Ni0.8-xO2 for lithium ion batteries had been prepared by coprecipitation and their properties had been characterized. By using XRD, XPS and constant current charge discharge tests, the effects of Mn content in LiMnxCo0.2Ni0.8-xO2 on structure and electrochemical properties were investigated. With the increase of Mn content in LiMnxCo0.2Ni0.8-xO2, the oxidation state of O and Ni of the samples were decreased, in which the valence of Ni was reduced from ＋3 to 4-2, while Mn was 4-4. Moreover, the rate capability of the sample declined, but the structure stability and anti-overcharge ability had been improved. Although XRD showed that the samples LiMnxCo0.2Ni0.8-xO2 （O≤x≤0. 5） had all a single phase of a hexagonal α- NaFeO2 structure, the change of cell parameters with the Mn content in LiMnxCo0.2Ni0.8-xO2 indicated that a pseudo solid solution LiMnxCo0.2Ni0.8-xO2 with 0≤x≤0. 25 could be formed. When the content of Mn ranged from 0.3 to 0.5, a true solid solution was formed.

关 键 词：锂离子电池 正极材料 LiMnxCo0.2Ni0.8-xO2 电化学性能 

分 类 号：TM912.2[电气工程—电力电子与电力传动] TG139.7[一般工业技术—材料科学与工程]