液相Al3+掺杂LiAlxMn2-xO4的化学合成及其电化学性能

摘要

采用工业上常用的碳酸锰热解法制备锰氧化物前驱体，与 Li2CO3混合后焙烧得到锂离子电池正极材料LiMn2O4，并在碳酸锰制备过程中掺入铝离子制备LiAlxMn2−xO4( x=0.01,0.02,0.03,0.05,0.1)。通过X射线衍射(XRD)和扫描电镜(SEM)对样品进行表征，并对合成材料在常温和高温(55℃)下的电化学性能进行研究。结果表明：合成的前驱体及锰酸锂材料均无杂相；随着 Al3+掺杂量的增加，LiAlxMn2­xO4颗粒尺寸不断长大；材料的首次充放电比容量随 Al3+掺杂量的升高而下降，但循环性能提高；Al3+的掺入极大地提高了材料的循环性能，尤其是在高温条件下，当掺杂量x=0.05时，1C倍率下循环100次容量的保持率由未掺杂的72.2%升高到90.7%。%　　The spinel LiMn2O4 was synthesized by manganese carbonate pyrolysis method and Al3+was doped during the MnCO3 synthesis process to get LiAlxMn2−xO4 (x=0.01, 0.02, 0.03, 0.05, 0.1). The samples were analyzed by X­ray diffraction (XRD), scanning electron microscopy (SEM) and their electrochemical performance were tested at room temperature and elevated temperature (55℃). The results of MnCO3 and LiMn2O4 have no apparent. With the increase of the doping amounts of Al3+, the particle sizes of LiAlxMn2­xO4 become larger, and the first discharge capacity of LiMn2O4 decrease to some degree. But the LiAlxMn2−xO4 electrode exhibits superior cycling performance. Especially, at elevated temperature (55℃), the capacity retention increases from 72.2%for LiMn2O4 to 90.7% for LiAl0.05Mn1.95O4 after 100 cycles at 1C.