控制结晶法合成表面富含钴的尖晶石LiMn_(2-x)Co_xO_4  

Synthesis of spinel LiMn_(2-x)Co_xO_4 with high cobalt content at surface by controlled crystallization

作　　者：张国昀[1] 姜长印[1] 万春荣[1] 应皆荣[1] 

机构地区：[1]清华大学核能技术设计研究院新型能源与材料化学研究室,北京102201

出　　处：《电源技术》2003年第1期17-19,23,共4页Chinese Journal of Power Sources

基　　金：国家自然科学基金项目(50002006);清华大学基础研究重点资助项目(JC1999054)

摘　　要：为了解决尖晶石LiMn2O4在高温下的容量衰减问题,制备出了表面富含钴的尖晶石LiMn2-xCoxO4。采用控制结晶工艺在Mn3O4颗粒表面包覆一层β Co(OH)2,以包覆Co(OH)2的Mn3O4为前驱体,与LiOH·H2O混合,在750℃下反应20h,合成表面富含钴的LiMn2-xCoxO4。X射线衍射分析表明,合成的LiMn2-xCoxO4为尖晶石结构,没有杂相。扫描电镜和能量散射光谱(EDS)的分析结果表明,该尖晶石LiMn2-xCoxO4为类球形,而且表面富含钴。这种表面富含钴的尖晶石LiMn2-xCoxO4在高温下仍然具有良好的电化学性能,在55℃下其首次放电比容量为101mAh·g-1,15次充放电循环之后,仍保持初始放电容量的99%。而尖晶石LiMn2O4在15次循环后,仅能保持初始放电容量的82%。Spine LiMn2-xCoxO4 with high cobalt content at surface was prepared in order to inhibit capacity fading of LiMn2O4 at elevated temperature. The surface of Mn3O4 particle was coated with βCo(OH)2 by means of controlled crystallization method. The Mn3O4 coated with Co(OH)2, as the precursor, was mixed with LiOH·H2O at 750 ℃ for 20 h, so the LiMn2-xCoxO4 with high cobalt content at surface was synthesized. The analysis of Xray diffraction shows that the synthesized LiMn2-xCoxO4 is pure spinel structure without impurity phase. The analytical results of scanning electron micrograph (SEM) and energy diffraction spectroscopy(EDS) show that the spinel LiMn2-xCoxO4 powder is spherical particles with high cobalt content at surface. The synthesized LiMn2-xCoxO4 with high cobalt content at surface has good electrochemical property at elevated temperature. Its initial specific discharge capacity is 101 mAh/g at 55 ℃ and the retention of discharge capacity is 99% to the initial value after 15 cycles. However, the dischargecapacity retention of spinel LiMn2O4 is only 82% to the initial value after 15 cycles.

关 键 词：控制结晶法 合成 钴 尖晶石 LiMn2-xCoxO4 锂离子蓄电池 正极材料 

分 类 号：TM912.2[电气工程—电力电子与电力传动]