Synthesis of high tap-density layered LiMn_0.4Ni_0.4Co_0.2O₂ cathode material

Uniform spherical metal hydroxide Mn_0.4Ni_0.4Co_0.2(0H)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 2.3 g·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 164 mAh·g^-1 at a voltage range from 3.0 to 4.0 V and a current density of 30 mA·g^-1, and 90% of the discharge capacity is retained after 50 charge-discharge cycles.