Enhanced electrochemical performances of Na-doped cathode material LiNi1/3Co1/3Mn1/3O2 for lithium-ion batteries

Abstract

The Na-doped layer-structured Li1−x Na x Ni1/3Co1/3Mn1/3O2 (x = 0, 0.01, 0.03, 0.05, 0.07) cathode materials for lithium-ion batteries have been successfully synthesized by co-precipitation reaction combined with solid-state sintering method. The structure and morphologies of cathode materials Li1−x Na x Ni1/3Co1/3Mn1/3O2 (x = 0, 0.01, 0.03, 0.05, 0.07) were measured by the powder X-ray diffraction, a field emission scanning electron microscope, energy-dispersive spectrometer, energy-dispersive X-ray spectroscopy and transmission electron microscope. The electrochemical performances were measured by galvanostatic charge–discharge test at different rates, electrochemical impedance spectroscopy and cyclic voltammetry. Compared with pristine sample, the Na-doped cathode materials have higher discharge specific capacity, more excellent cycling stability and better rate performance. The sample of Li0.95Na0.05Ni1/3Co1/3Mn1/3O2 has the most excellent electrochemical performances. It exhibits 204.5 m Ahg−1 initial discharge specific capacity and 87.2% capacity retention after 30 cycles at 0.1 C in the voltage range of 3.0–4.8 V. While the pristine LiNi1/3Co1/3Mn1/3O2 material illustrates 187.1 m Ahg−1 initial discharge specific capacity and 78.4% capacity retention after 30 cycles at 0.1 C in the voltage range of 3.0–4.8 V.