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 LiMn2-xCoxO4 with high cobalt content at surface was prepared in order to inhibit capacity fading of LiMn2O4 at elevated temperature. The surface of Mn3O4 particle was coated with βCo(OH)2 by means of controlled crystallization method. The Mn3O4 coated with Co(OH)2, as the precursor, was mixed with LiOH·H2O at 750 ℃ for 20 h, so the LiMn2-xCoxO4 with high cobalt content at surface was synthesized. The analysis of Xray diffraction shows that the synthesized LiMn2-xCoxO4 is pure spinel structure without impurity phase. The analytical results of scanning electron micrograph (SEM) and energy diffraction spectroscopy(EDS) show that the spinel LiMn2-xCoxO4 powder is spherical particles with high cobalt content at surface. The synthesized LiMn2-xCoxO4 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 dischargecapacity retention of spinel LiMn2O4 is only 82% to the initial value after 15 cycles.
出处
《电源技术》
CAS
CSCD
北大核心
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)
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
lithium ion battery
spinel LiMn_(2-x)Co_xO_4 with high cobalt content at surface
controlled crystallization
Mn_3O_4
β-Co(OH)_2
