Abstract:LiNi0.4Co0.2Mn0.4O2 cathode material for Li-ion batteries was synthesized by sintering process with Ni0.4Co0.2Mn0.4(OH)2 precursor and Li2CO3 as raw materials in air atmosphere. Morphology and crystal structure were evaluated by SEM and XRD before and after sintering Ni0.4Co0.2Mn0.4(OH)2 precursor with Li2CO3. Electrochemical properties of LiNi0.4Co0.2Mn0.4O2 cathode material were tested. The results show that primary particles of Ni0.4Co0.2Mn0.4(OH)2 precursor are of obvious layered structure. Cathode material LiNi0.4Co0.2Mn0.4O2 has obvious hexagonal layered type structure with low cation mixing factor of c/a=4.967 3, ratio of characteristic peaks I(003)/I(104)=1.25, I(006+102)/I(101)=0.333, and I(018)/I(110)=0.87. The initial discharge capacity of LiNi0.4Co0.2Mn0.4O2 is 166 and 154 mAh/g respectively in the voltage range of 2.5~4.6 V at 0.2C and 0.5C. The reversible capacity is 111 and 100 mAh/g respectively after 80 cycles.