多孔结构Li_3V_2(PO_4)_3/C正极材料的制备及电化学性能

Preparation and electrochemical performance of macporous Li_3V_2(PO_4)_3/C cathode material

以Li2CO3、NH4H2PO4、V2O5、草酸及淀粉为原料,采用高温固相法合成了具有多孔结构的Li3V2(PO4)3/C复合材料,研究了合成温度对材料结构和电化学性能的影响。采用X射线衍射(XRD)、扫描电镜(SEM)对不同温度下合成的Li3V2(PO4)3/C结构和形貌进行表征,并用恒电流充放电及交流阻抗检测方法研究材料的电化学性能。结果表明:800℃合成材料具有最佳的多孔结构及电化学性能。0.1 C初始放电比容量为130 mAh/g,经20次循环后,放电比容量仍然保留124.9 mAh/g,为初始放电比容量的96.1%。2 C下循环50次材料仍有91.5 mAh/g的放电比容量,比容量损失率仅为7%。对800℃下制备的多孔Li3V2(PO4)3/C复合材料具有最佳电化学性能的原因进行了初步研究。

The macporous Li3V2（PO4）3/C composite was synthesized by solid-state reaction using Li2CO3, NH4H2PO4, V2O5, oxalic acid and starch. The influence of calcination temperature on the material morphology and electrochemical performance was also investigated. The samples prepared at different temperatures were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV） and electrochemical impedance spectroscopy （EIS）.The results show that the sample synthesized at 800 ~C presents the best macporous morphology and electrochemical performance. The initial discharge specific capacity of the sample is 130.0 mAh/g at 0.1 C and after 20 cycles the discharge specific capacity is 124.9 mAh/g with 96.1% retention of the initial capacity. Even at 2 C after 50 cycles the discharge specific capacity is still up to 91.5 mAh/g with the capacity loss of only 7%. The reasons for the excellent electrochemical performance of the macporous Li3V2（PO4）3/C sintered at 800℃ cathode material were discussed.