富锂型掺钴尖晶石锂锰氧化物的结构与电化学性能
来源期刊：中南大学学报(自然科学版)2004年第3期
论文作者：李运姣 常建卫 李洪桂 赵中伟 孙召明 霍广生 孙培梅
文章页码：381 - 385
关键词：掺钴;锂锰氧化物;结构;电化学性能
Key words：cobalt-doped; lithium manganese oxide; structure; electrochemical performance
摘 要：采用湿化学方法合成了富锂型掺钴尖晶石锂锰氧化物Li1.02Mn2-y-CoyO4 (y=0,0.02,0.10,0.50),并通过X射线衍射与恒电流充、放电等测试方法对合成产物的结构与电化学性能进行了研究。X射线衍射结果表明:当掺钴量y≤0.10时,合成产物属于尖晶石结构;当y=0.50时,开始有少量Co3O4的杂相峰出现,但仍以尖晶石结构为主;随着y的增加,合成样品的晶胞常数减小,晶胞体积收缩,晶胞中Mn—O之间的距离(RMn—O)与Mn—Mn之间的距离(R Mn—Mn)均缩短。恒电流充、放电实验结果表明,随着y的增加,合成产物的初始放电比容量有所降低,但稳定性提高;当y= 0. 02时,合成产物的初始放电比容量为118. 860 mA·h/g,循环5次后,其比容量为115.796 mA·h/g。综合合成产物的比容量与循环性能,以Li1.02Mn1.98Co0.02O4的电化学性能为最佳。
Abstract: The Li-rich spinel lithium manganese oxide with doping cobalt was prepared by wet chemistry method. The structures and electrochemical performances of the products were studied. The results of X-ray diffraction experiments show that the cathode material (Li1.02Mn2-y-CoyO4) has a spinel structure when y≤0.10. However, the main structure is spinel, with little Co3O4 in the sample when y=0.50. Spinel lattice constants,RMn—O and RMn—Mn decrease with the increase of the doping amount of cobalt. The results of constant current cyclic tests show that the cyclic stability of the product increases with the doping amount of cobalt, while its initial discharge capacity decreases. The initial discharge capacity of the product when y=0.02 is 118.860 mA·h/g, and the discharge capacity is 115.796 mA·h/g after five cycles. According to both the capacity and the cyclic property, the product with doping cobalt of y=0.02 has the optimized performance.
