Abstract: Ni0.45Co0.1Mn0.45(OH)2was prepared via improved hydroxide co-precipitation. The effect of reaction condition on the shape of the product, and the effect of F- ion on the morphology and tap-density of the product were studied. LiMn0.45Ni0.45Co0.1O2 and LiMn0.45Ni0.45Co0.1O1.96F0.04 were prepared by mixing this metal hydroxide with 5% excess LiOH followed by heat-treatment. The effect of F doping on the cycling performance of the prodct was investigated. The morphology and tap-density of the product were improved through the addition of F- in co-precipitation system. The product was characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and charge-discharge tests. It can be seen from the SEMresults that the product has a good shape. The XRD studies showed that the material had a well-ordered layered structure without impurity phase. The initial capacities of both LiMn0.45Ni0.45Co0.1O2 and LiMn0.45Ni0.45Co0.1O1.96F0.04 are 157 mAh·g-1 at a charging potential between 2.8 and 4.4 V and a current density of 30 mA·g -1. The 72.6% and 86.0% discharge capacities were retained at the end of 50 charge-discharge cycles, respectively. It is shown that the F doping can obviously improve the cycling performance of the product.

Key words: Lithiumion secondary battery, Cathodematerial, Co-precipitation, LiMn0.5-xNi0.5-xCo2xO2, F doping