非均匀沉淀法包覆合成LiNi_(0.9)Co_(0.07)Mn_(0.03)O_2锂离子正极材料

Synthesis of coated-LiNi_(0.9)Co_(0.07)Mn_(0.03)O_2 cathode materials by heterogeneous nucleation

采用非均匀沉淀法包覆合成了LiN i0.9Co0.07Mn0.03O2锂离子正极材料。前驱体合成中各工艺条件与包覆材料的比表面积和电化学性能息息相关。试验研究了沉淀剂、搅拌速度、pH值和氨水浓度对包覆沉淀的影响及煅烧过程对材料电化学性能的影响。结果表明:在优化实验条件下Co/Mn复合包覆在-βN i(OH)2表面上;正极LiN i0.9Co0.07Mn0.03O2首次放电容量为195mAh.g-1,50次循环后容量仍保持为188.6mAh.g-1。循环伏安研究表明:与LiN iO2相比,Co/Mn复合包覆合成正极材料LiN i0.9Co0.07Mn0.03O2的相变得到很好的抑制,材料显示出良好的循环性能。

LiNi0.9Co0.07Mn0.03O2 powders were synthesized by heterogeneous nucleation. And the specific surface area and electrochemical propertis of samples were significantly dependent on synthetic condition, such as precipitation agent, pH, stirring speed, in synthesis process. Then the calcinations condition were studied. The results show that under optimum condition the sample is coated homogeneously; The initial discharge capacity of the materials is 195 mAh·g^-1, and the discharge capacity remains 188.6 mAh·g^-1 after 50 cycles numbers. The cyclic voltammetry results show that the improvement of capacity retention should be linked to suppression of the phase transition, compared to LiNiO2.