镁掺杂改性磷酸铁锂正极材料及其性能研究

Study on Synthesis and Performances of Lithium Iron Phosphate as Cathode Materials by Mg-doping

采用碳热还原法合成LiFe1-x Mgx PO4/C(x=0.01、0.02、0.03、0.05、0.10)正极材料,并通过XRD、SEM、恒流充放电等测试方法表征材料的物相结构及电化学性能。结果表明:获得的所有材料均为橄榄石型结构,不同掺镁量对材料的颗粒形貌及颗粒尺寸未有较大影响。当x=0.02时,LiFe0.98Mg0.02PO4/C材料具有良好的循环稳定性和高倍率放电性能,1C倍率50次循环后,容量保持率可以达到98.6%;以0.2C倍率充放,放电比容量为130.3mAh/g,分别以5C、10C倍率放电,放电比容量仅下降21.3%、28.4%。

LiFel-xMgxPO4/C（x= 0. 01,0.02,0.03,0. 05,0. 10） were synthesized hy carhothermal reduction method, and the phase structures and electrochemical performances were characterized by X-ray diffraction（XRD）, scanning electron microscope（SEM） and constant current charge-discharge tests. The experimental results show that all materials have perfect phosphor-olivine structure, and there is no significant difference in particles morphology and size with different content of Mg2＋. LiFe0. 98 Mg0.02 PO4/C（x=0. 02） exhibits better cycling performance and high rate discharge capacity. The capacity retention ratio of the material can reach 98. 6~ at 1C for 50 cycles. When the elec trode was charged and discharged at 0. 2C,its discharge specific capacity can reach 130. 3 mAh/g. And the electrodes were charged at the same rate, but those were discharged at 5C, 10C respectively, and the discharge specific capacity of LiFe0. 98 Mg0. o2 PO4/C at 5C, 10C only decrease 21.3 %, 28. 4 % of that at 0. 2C.