锂离子蓄电池正极材料LiNi_(1-y)Co_yO_2的合成及性能

Synthesis and performance of LiNi_(1-y)Co_yO_2 as cathode material for lithium ion batteries

采用球形氢氧化镍的生产工艺合成了Ni1-yCoy(OH) 2 (0≤y≤ 0 .5 )共沉淀前驱体 ,利用该前驱体和锂盐一同焙烧后得到系列LiNi1-yCoyO2 固溶体。该方法避免了共沉淀时胶体的生成 ,而且与普通高温固相产物相比 ,烧成后的Li Ni1-yCoyO2 产物不仅保持了前驱体的原有形貌 ,而且具有更优良的电化学性能。通过电化学性能测试、SEM及X射线衍射等分析方法 ,我们系统研究了不同Co含量对材料电化学性能、结构以及前驱体形貌的影响。随着Co含量的增加 ,材料粒度逐渐降低 ,颗粒形貌由球形变为不规则形状 ;并且LiNi1-yCoyO2 材料的充放电及不可逆容量、放电电压均随Co含量的增加而呈降低趋势。当 0 .10≤y≤ 0 .2 0时 ,材料比容量可达 190mAh/g以上 。

The co precipitation precursor of Ni 1-y Co y(OH) 2(0≤y≤0.5) was synthesized by means of the manufacturing technology for spherical nickel hydroxide, and the LiNi 1-y Co yO 2 solid solutions were prepared by baking the precursor with lithium salt together. By this method, no colloid was produced during co precipitation, and the baked LiNi 1-y Co yO 2 maintained the original morphology of precursor and had higher electrochemical performance compared with the ordinary product synthesized by high temperature solid state method. Effects of Co content on electrochemical performance and structure of the material and morphology of precursor were studied by means of electrochemical performance test, SEM and XRD. The results show that with the increase of Co content, the particle size of material is decreased and the particle morphology is changed from sphericity to irregular shape. The charge/discharge capacity, irreversible capacity and discharge voltage of LiNi 1-y Co yO 2 material are decreased with the increase of Co content. When 0.10≤y≤0.20, the specific capacity of the material is more than 190 mAh/g and its cyclic performance is best.