钼掺杂Li3V2（PO4）3/C正极材料的制备及其电化学性能研究

以Li2CO3、NH4H2PO4、V2O5和MoO3为原料,柠檬酸为络合剂和碳源,采用溶胶-凝胶法制备了锂离子正极材料Li3MoxV2-x(PO4)3/C(x=0.01,0.02,0.03).X射线衍射(XRD)表明,合成的材料具有单一的单斜晶系结构,空间群为P21/n.扫描电镜(SEM)显示Li3Mo0.02V1.98(PO4)3/C具有均一的表面形貌.恒流充放电测试表明,当x=0.02时,掺杂后的Li3Mo0.02V1.98(PO4)3具有最佳的电化学性能.在1C倍率下,3.0～4.3 V电位区间,Li3Mo0.02V1.98(PO4)3/C的首次放电比容量达到122.3 mAh.g-1,循环50周之后,容量没有衰减的迹象;而当x=0、0.01和0.03时,首次放电比容量仅分别为117.1、115.1和116.0 mAh.g-1.在3C和5C倍率下,样品Li3Mo0.02V1.98(PO4)3/C仍能保持优异的循环稳定性.

Preparation and Electrochemical Performance of Mo-Doped Li3V2（PO4）3/C Cathode Materials

The molybdenum-doped Li3V2-xMox(PO4)3/C(x=0.01,0.02 and 0.03) cathode materials were prepared with a sol-gel method by using Li2CO3,NH4H2PO4,V2O5 and MoO3 as raw materials,and citric acid as both chelating reagent and carbon source.The X-ray diffraction(XRD) analyses showed that the crystal structure of as-prepared samples is monoclinic with space group P21/n.Scanning electron microscopy(SEM) observations indicated the uniform morphology for Li3Mo0.02V1.98(PO4)3/C sample.Galvanostatic charge/discharge tests revealed that the optimal Mo-doping proportion is x=0.02,and the best initial discharge capacity of Li3Mo0.02V1.98(PO4)3/C reaches 122.3 mAh·g-1 in the voltage range of 3.0~4.3 V at 1C rate with almost no capacity loss after 50 cycles.However,at x=0,0.01 and 0.03,the initial discharge capacities are 117.1 mAh·g-1,115.1 mAh·g-1 and 116.0 mAh·g-1,respectively.Even at 3C and 5C rates,the Li3Mo0.02V1.98(PO4)3/C sample also exhibits excellent electrochemical performance.