Electrochemical properties of LiNi0.6Co0.12Mn0.2V0.08O2 as the tetrad cathode material of lithium-ion battery under high cut-off voltages.

In the study, a new kind of tetrad cathode lithium-ion battery material (LiNi0.6Co0.2-xMn0.2VxO2 (x = 0, 0.06, 0.08, 0.10)) was synthesized and then characterized by XRD, XPS, SEM, EDS, electrochemical measurements, CV, and EIS. The homogenous distribution of vanadium element on the materials was verified and the layer crystal structure was not changed when x = 0.08. XPS results indicated that suitable vanadium substitution reduced cation mixing on the surface due to the lower content of Ni2+. Electrochemical measurements confirmed that LiNi0.6Co0.12Mn0.2V0.08O2 had the highest initial coulombic efficiency (80 % at 0.05 C), rate capacity (129.4 mAh/g at 5 C), and cycling performance (92.6% at 1 C) at the cutoff voltage of 4.6 V, which were much better than those of LiNi0.6Co0.2Mn0.2O2. LiNi0.6Co0.12Mn0.2V0.08O2 showed good dynamic properties in CV and EIS tests. The results of XRD and SEM for cycled electrodes showed that the introduction of vanadium could significantly relieve structural damages of LiNi0.6Co0.2Mn0.2O2 during charge/discharge processes. This study indicated that controlled vanadium introduction could effectively improve the electrochemical performance of LiNi0.6Co0.2Mn0.2O2 for developing the high-voltage cathodes for high-energy lithium-ion batteries. [ABSTRACT FROM AUTHOR]