耐久型高倍率性能锰酸锂微球的合成

摘要

以Mn2+和NH4HCO3为原料,通过控制结晶法合成球形MnCO3前驱体模板.以LiNO3和MnCO3为原料,按照一定的摩尔比机械混合,在700℃下煅烧8h,合成高倍率性能和长循环性能的球形尖晶石LiMn2O4材料.分别考查原料的摩尔比、反应时间以及反应温度对前驱体MnCO3形貌和产率的影响.采用X射线粉末衍射和扫描电镜对合成的MnCO3和LiMn2O4进行表征,对LiMn2O4样品进行室温条件下的充放电性能测试.电化学测试结果表明:尖晶石锰酸锂微球在10C的放电倍率下的首次放电容量达90 mA·h/g (1C放电容量为148 mA/g),800次循环后容量保持率达到75％.该方法合成的LiMn2O4微球作为高功率型锂离子电池的正极材料有着较好的应用前景.%Spinel LiMn2O4 microspheres with durable high rate capability were synthesized by a facile route using spherical MnCO3 precursors as the self-supported templates,combined with the calcinations of LiNO3 at 700 ℃ for 8 h.The spherical MnCO3 precursors were obtained from the control of the crystallizing process ofMn2+ ions and NH4HCO3 in aqueous solution.The effects of the mole ratio of the raw materials,reaction time,and reaction temperature on the morphology and yield of the MnCO3 were investigated.The as-synthesized MnCO3 and LiMn2O4 microspheres were characterized by powder X-ray diffractometry (XRD) and scanning electron microscopy (SEM).Galvanostatic charge/discharge tests indicate that the spinel LiMh2O4 microspheres deliver a discharge capacity of 90 mA·h/g at 10C rate show good capacity retention capability (75％ of their initial capacity after 800 cycles at 10C rate).The durable high rate capability suggests that the as-synthesized LiMn2O4 microspheres are promising cathode materials for high power lithium ion batteries.