以溶液法制备的钠掺杂锂离子电池正极材料Li3-xNaxV2(PO4)3/C

摘要

A cathode material of lithium ion batteries Li3-xNaxV2(PO4)3/C(x=0,0.01,0.03,0.05, 0.07)was synthesized by solution method with glucose as the carbon source. XRD patterns illustrate that the constituent is of typical monoclinic crystal and coincide exactly with diffraction peaks of Li3V2(PO4)3. Sodium ion doesn't change the ingredient and crystal structure of product but change the lattice parameters. This tiny change of lattice parameters is conductive to the lithium ion diffusion. The cathode material particles are nearly elliptic in the SEM and TEM images. Particles are in even size distribution and have integrated carbon coating. The results of the charge-discharge tests proved that Li2.97Na0.03V2(PO4)3/C has the best rate performance with a discharge capacity of 100mAh/g at 12C rate. CV test demonstrates the diffusion coefficient of this sample is about two orders of magnitude higher than that of pure Li3V2(PO4)3.%以溶液法为制备方法、以葡萄糖为碳源合成了一种钠离子掺杂的锂离子电池正极材料 Li3-xNaxV2(PO4)3/C (x=0、0.01、0.03、0.05、0.07).XRD结果显示组成相为单斜晶型,与标准Li3V2(PO4)3衍射峰完全一致.微量钠掺杂并未改变产物的相组成与晶体结构,但使得晶胞参数有所变化,这种变化有利于提高锂离子的扩散系数.SEM 与 TEM 谱图显示材料颗粒基本为近似椭圆形,粒径分布均匀,碳包覆层完整.充放电测试显示Li2.97Na0.03V2(PO4)3/C试样的倍率性能最好,在12C倍率下放电比容量约为100mAh/g,循环伏安测试也证明该试样的锂离子扩散系数较高,比纯相Li3V2(PO4)3提高了约2个数量级.