Enhanced cycling stability of Mg–F co-modified LiNi0.6Co0.2Mn0.2–yMgyO2–zFz for lithium-ion batteries

Abstract The layered LiNi 0.6 Co 0.2 Mn 0.2– y Mg y O 2– z F z (0≤ y ≤0.12, 0≤ z ≤0.08) cathode materials were synthesized by combining co-precipitation method and high temperature solid-state reaction, with the help of the ball milling, to investigate the effects of F–Mg doping on LiNi 0.6 Co 0.2 Mn 0.2 O 2 . Compared with previous studies, this doping treatment provides substantially improved electrochemical performance in terms of initial coulombic efficiency and cycle performance. The LiNi 0.6 Co 0.2 Mn 0.11 Mg 0.09 O 1.96 F 0.04 electrode delivers an high capacity retention of 98.6% during the first cycle and a discharge capacity of 189.7 mA·h/g (2.8–4.4 V at 0.2 C ), with the capacity retention of 96.3% after 100 cycles. And electrochemical impedance spectroscopy(EIS) results show that Mg–F co-doping decreases the charge-transfer resistance and enhances the reaction kinetics, which is considered to be the major factor for higher rate performance. It is demonstrated that LiNi 0.6 Co 0.2 Mn 0.11 Mg 0.09 O 1.96 F 0.04 is a promising cathode material for lithium-ion batteries for excellent electrochemical properties.