LiFePO4-MWCNTs复合正极材料的制备与电化学性能研究

以氧化铁为铁源,通过简单的固相碳热法制备LiFePO4-MWCNTs复合正极粉体材料.利用XRD和SEM表征LiFePO4-MWCNTs复合材料的结构和表面形貌.利用EIS、CV和充放电测试实验测量LiFePO4-MWCNTs复合材料的电化学性能.XRD结果显示复合材料为橄榄石型的磷酸铁锂纯相,多壁碳管在正极材料中将颗粒相连,增加导电面积,形成三维网络结构,为颗粒之间提供附加的导电通道.通过添加质量分数为5%的多壁碳管的方法对LiFePO4正极材料导电通道进行改善.在0.5C充放电速率下首次放电比容量可以达到151.6mAh/g,充放电50次后,放电比容量还能保持在145.5mAh/g,在1C充放电速率下比容量保持在140mAh/g,2C时比容量保持在130mAh/g.随着充放电速率的增加,锂离子电池的性能也更加优越.

Preparation and Properties of LiFePO4-MWCNTs Composite Cathode Material

LiFePO4-MWCNTs cathode materials were synthesized by a simple solid-states carbothermal reduction(CTR) using Fe2O3 as raw material.The structures and morphological performances of LiFePO4-MWCNTs composites were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM).The electrochemical properties for LiFePO4-MWCNTs composites were measured by electrochemical impedance spectroscopy(EIS) and charge/discharge experiments.The XRD and SEM result shows that the samples have an olivine-type phase,MWCNTs connect active particles to increase the superficial area with particles to form a three-dimensional network structure.LiFePO4-MWCNTs synthesized at 800 ℃ for 20 h with glucose as carbon source shows the electrochemical performance with an initial discharge specific capacity of 151.6 mAh/g at 0.5 C rate and remains to be 145.5 mAh/g after 50 cycles,keep 140 mAh/g at 1 C and 130 mAh/g at 2 C.Along with the increase of the charge and discharge rate,the performance of Lithium ion battery becomes better.