非均匀成核法表面包覆氧化铝的尖晶石LiMn_2O_4研究

Study on Al_2O_3-modified LiMn_2O_4 Prepared by Heterogeneous Nucleation

采用高温固相法合成尖晶石LiMn2O4,以非均匀成核方式对其进行包覆氧化铝的表面处理.通过XRD、SEM、粒度分析等技术对表面处理前后的LiMn2O4进行表征,分析了表面处理前后LiMn2O4物理特性的变化,并结合电化学性能测试,研究了表面处理工艺对LiMn2O4电化学容量与循环性能的影响.未经表面处理的LiMn2O4在1C倍率下初期放电容量为86.5mA·h·g-1,50次循环充放电后容量衰减26.3%.表面包覆0.5%、1%(w)氧化铝的LiMn2O4在1C倍率下的初期放电容量分别为96.0、80.1mA·h·g-1,经过50次循环后,容量分别降低7.0%、5.6%.实验结果表明,表面处理后的LiMn2O4循环性能显著提高,而且随着氧化物含量的增加,循环性能增强,但放电容量降低.

The spinel LiMn2O4 synthesized by the method of solid-state reaction was modified with aluminum oxide through the heterogeneous nucleation process. The pristine and surface-modified spinel LiMn2O4 were characterized with X-ray diffraction (XRD), scanning electron microscope(SEM) and particle size analysis. Effects of the surface-modification and preparation conditions on the cycleability and the rate capability were studied. The initial capacity of unmodified LiMn2O4 was 86.5 mA . h . g(-1) and the capacity fade was 26.3% after 50 cycles. The initial capacities of LiMn(2)O(4)modified with 0.5% and 1% (w) aluminum oxide were 96. 0 mA . h . g(-1) and 80.1 mA . h . g(-1), and the capacity fades were 7.0% and 5.6%, respectively. The results showed that the cycling, life of LiMn2O4 was clearly improved by modification of aluminum oxide through the process of heterogeneous nucleation. With the increase of aluminum oxide, the cycling life increases, however, the capacity obviously decreases. The process of heterogeneous nucleation showed some special characters, such as the homogeneous coating. It is more suitable for the surface-modification of LiMn2O4.