Enhanced electrochemical performance of F-doped Li1.2Mn4/6Ni1/6Co1/6O2.35 cathode materials for Li-ion batteries

Abstract

F-doped cathode material Li1.2Mn4/6Ni1/6Co1/6O(2.35-x)Fx (x=0,0.05,0.10,0.15) were synthesized successfully by two-step co-precipitation method. X-ray diffraction pattern shows that fluorine doping does not bring impurities, but the lattice parameters increase slightly with fluorine content increasing in Li1.2Mn4/6Ni1/6Co1/6O(2.35-x)Fx. At the current density of 0.5C (125mAhg−1), Li1.2Mn4/6Ni1/6Co1/6O2.30F0.05 has the highest capacity retention (94.56%) and discharge capacity(177.4mA·h/g) after 50th cycles, while capacity retention and discharge capacity after 50th cycles of Li1.2Mn4/6Ni1/6Co1/6O2.35 material are only 86.19% and 164.7 mA·h/g. And Li1.2Mn4/6Ni1/6Co1/6O2.30F0.05 material exhibits a noticeable higher discharge capacity than other Li1.2Mn4/6Ni1/6Co1/6O(2.35-x)Fx (x=0, 0.10,0.15) materials at high current density. The initial discharge specific capacity of Li1.2Mn4/6Ni1/6Co1/6O2.30F0.05 material is increased to 121.1 mA·h/g and 82.3 mA·h/g compared to 91.1 mA·h/g and 66.8 mA·h/g of Li1.2Mn4/6Ni1/6Co1/6O2.35 material at 2C and 5C. It can be concluded that electrochemical performances of Li1.2Mn4/6Ni1/6Co1/6O2.35 material are improved due to fluorine doping.