LiFe_(0.8)Mn_(0.2)PO_4的制备、表征及电化学性能研究

Research on preparation,characterization,and electrochemical performances of LiFe_(0.8)Mn_(0.2)PO_4

使用共沉淀法分别制备了纯相磷酸亚铁锂(LiFePO4)和磷酸亚铁锂掺锰材料LiFe0.8Mn0.2PO4,以期在不降低体积比容量的前提下提高磷酸亚铁锂材料的导电性。通过对产品的X射线衍射(XRD)分析,证实掺杂Mn2+并未改变磷酸亚铁锂的正交橄榄石型晶体结构;扫描电镜(SEM)显示LiFe0.8Mn0.2PO4比纯相磷酸亚铁锂具有更小的粒径,从而有利于Li+的扩散,进而有助于提高其电化学活性;通过对产品的电化学性能测试比较,掺杂Mn2+后的材料,无论是放电容量或是高倍率下的循环性能都优于纯相磷酸亚铁锂。

Pure phase LiFePO4 and LiFe0.8Mn0.2PO4 were prepared respectively by co-precipitation method,in order to improve the conductance of LiFePO4 material without reducing the specific capacity.XRD results confirmed that the doping of Mn2＋ into LiFePO4 didn′t change the olivine orthogonal crystal structure;SEM results showed that the diameter of LiFe0.8Mn0.2PO4 particles was much smaller than that of LiFePO4,which was conductive to the diffusion of Li＋ and thus would help to improve its electrochemical activity;through the comparison of electrochemical performance tests for the two materials,it was found that the material of LiFe0.8Mn0.2PO4 had higher discharge capacity and better cycle capability at high rate.