草酸盐共沉淀法制备层状LiNi_(1/3)Co_(1/3-x)La_xMn_(1/3)O_2正极材料

Preparation of layered LiNi_(1/3)Co_(1/3-x)La_xMn_(1/3)O_2 as cathode material by oxalate co-precipitation method

采用草酸盐共沉淀法制备了锂离子电池用稀土元素镧掺杂层状正极材料LiNi1/3Co1/3-xLaxMn1/3O2(0<x<1),考察了镧掺杂对其结构与电化学性能的影响。XRD与电化学性能测试结果表明,层状正极材料LiNi1/3Co1/3-0.04La0.04Mn1/3O2具有较好的层状结构和综合电化学性能。表征阳离子的混排程度的峰强比I(003)/I(104)=1.249>1.2,表示六角晶格的有序性的R因子R=0.5。在2.8～4.2 V(vs.Li/Li+)电压范围,0.1 C倍率的首次放电比容量为147.56 mAh/g,首次充放电效率为94%,0.2 C倍率循环20次后继续以0.5 C倍率循环20次的可逆比容量为141.7 mAh/g,为首次放电比容量的96.0%。SEM结果表明,颗粒平均粒径约1.2 mm,形状近似于球形。

The layered Li[Ni1/3Co1/3-xLaxMn1/3]O2（0x1） was synthesized by oxalate co-precipitation method.The influence of La-dopants on the structural and electrochemical properties of the Li[Ni1/3Co1/3Mn1/3]O2 materials was studied.The results show that LiNi1/3Co1/3-0.04La0.04Mn1/3O2 deliveres a better layer-structural and good electrochemical properties.The XRD analysis indicates that the presently synthesized Li[Ni1/3Co1/3-0.04Mn1/3]O2 has a hexagonal layered-structure.The initial specific discharge capacity of the Li[Ni1/3Co1/3-0.04Mn1/3]O2 positive-electrode material is determined to be 147.56 mAh/g using a Li/Li[Ni1/3Co1/3Mn1/3]O2 cell operated at 0.1 C ratio in voltages of 2.8-4.2 V.The discharge capacity is 141.7 mAh·g-1 after 20 cycles with 0.2 C ratio and 20 cycles with 0.5 C ratio.The spherical particle size distribution of the Li[Ni1/3Co1/3-0.04Mn1/3]O2 powder was observed via scanning electron microscopy.The average particle size is measured to be about 1.2 mm in diameter.