The Electrochemical Performance of Mg-F Co-doped Spinel LiNi0.5Mn1.5O4 Cathode Materials for Lithium-Ion Battery

Abstract

The Mg doped and Mg-F co-doped spinel LiNi0.5Mn1.5O4 nanoparticles have been synthesized using a rheological method and investigated as high voltage cathode materials for rechargeable lithium-ion batteries. The results demonstrate that the Mg-F co-doped LiNi0.5Mg0.2Mn1.3O3.8F0.4 cathodes present an improved electrochemical performance over the pristine and Mg doped samples. After cycling at different current densities at 55 °C, the discharge capacities are 101.4 mAh g-1 for the LiNi0.5Mg0.2Mn1.3O3.8F0.4 cathode (90 % of the capacity retention), 73.3 mAh g-1 for the LiNi0.5Mg0.2Mn1.3O4 sample (71 % of the capacity retention), and 43.1 mAh g-1 for the pristine LiNi0.5Mn1.5O4 material (49 % of the capacity retention). The remarkable performances may be attributed to the doping of Mg ions which in turn suppress the John-Teller effect by increasing the average oxidation state of Mn ions. Furthermore, the doping of F ions provide a more stable crystal structures and smaller charge transfer resistance.