A novel layered material of LiNi_0.32Mn_0.33Co_0.33Al_0.01O₂ for advanced lithium-ion batteries

A novel layered material of LiNi_0.32Mn_0.33Co_0.33Al_0.01O₂ with α-NaFeO₂ structure is synthesized by sol-gel method. X-ray diffraction (XRD) shows that the cation mixing in the Li layers of it is decreased. In addition, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are employed to characterize the reaction of lithium-ion insertion and extraction from materials. The results indicate that the structure of LiNi_0.32Mn_0.33Co_0.33Al_0.01O₂ is more stable than that of the LiNi_0.33Mn_0.33Co_0.33O₂. The capacity retention of LiNi_0.33Mn_0.33Co_0.33O₂ after 40 cycles at 2.0 C is only 89.9%, however, that of the LiNi_0.32Mn_0.33Co_0.33Al_0.01O₂ is improved to 97.1%. The capacity of the LiNi_0.32Mn_0.33Co_0.33Al_0.01O₂ at 4.0 C remains 71.8% of the capacity at 0.2 C, while that of the LiNi_0.33Mn_0.33Co_0.33O₂ is only 54.3%. EIS measurement reveals that the increase in the charge transfer resistance during cycling is suppressed in the LiNi_0.32Mn_0.33Co_0.33Al_0.01O₂ material.