高密度LiMn0.4Ni0.4Co0.2O2正极材料的合成与研究

用一种改进的氢氧化物共沉淀法制备了粒径均一、近球形的Mn_0.4Ni_0.4Co_0.2(OH)₂, 再通过高温固相合成法制备了高密度的LiMn_0.4Ni_0.4Co_0.2O₂正极材料。结果表明，在沉 淀体系中加入F^-，可以在较为宽松的条件下制备出振实密度为2.3g·cm^-3的LiMn_0.4Ni_0.4Co_0.2O₂正极材料。对产物进行了XRD、SEM和充放电测试。SEM测试结果表明，产物具有良好的形貌; XRD测试表明，产物具有良好的层状结构，无杂质相存在。在充放电电压区间为3.0~4.4V,电流密度为30mA·g^-1时，首次充电和放电容量分别为185和164mAh·g^-1，经过50次循环，放电容量仍能保持90%。

Synthesis of High Tap-Density Layered LiMn0.4Ni0.4Co0.2O2 Cathode Material

Uniform spherical metal hydroxide Mn_0.4Ni_0.4Co_0.2(OH)₂ was prepared via improved hydroxide precipitation, and then LiMn_0.4Ni_0.4Co_0.2O₂ was prepared by mixing this metal hydroxide with 5% excess LiOH by heat-treatment. It is shown that the product with the high tap-density of 2.3g·cm^-3 can be prepared under relatively extensive condition via the addition of F^- in system. The product was characterized using X-ray diffraction(XRD), scanning electron microscope (SEM) and charge-discharge tests. The SEM results show that the product has a good morphology, and the XRD studies demonstrate that the material has a well-ordered layered structure without impurity phase. The initial charge and discharge capacities are 185 and 164mAh·g^-1 at a voltage range from 3.0 to 4.0V and a current density of 30mA·g^-1, and 90% of the discharge capacity is retained after 50 charge-discharge cycles.