Molten salt synthesis and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 cathode materials

LiNi1/3Co1/3Mn1/3O2 cathode materials were synthesized by molten salt method. The preparation was performed by sintering the mixture of Ni1/3Co1/3Mn1/3(OH) 2 and the eutectic molten salts 0.76LiOH·H2O-0.24Li2CO3 at 750–900 °C for 2–11 h. The prepared particles were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge test. XRD analysis shows the molten salt method can enhance the ordering degree of the layered structure and reduce the cation mixing of LiNi1/3Co1/3Mn1/3O2 compounds. The sample prepared at 850 °C for 5 h exhibits an excellent electrochemical performance. It can deliver an initial discharge capacity of 175.6 mAh g−1 at a current density of 16 mA g−1 between 2.8 and 4.4 V, and a capacity of 156.7 mAh g−1 is retained after 2, 10, 20 and 20 cycles at the corresponding current density of 16 mA g−1, 32 mA g−1, 80 mA g−1 and 160 mA g−1, respectively. At a current density of 320 mA g−1 followingly, it still exhibits a capacity of 150.5 mAh g−1 after 20 cycles. The electrochemical impedance shows the charge–discharge process of electrode is controlled by the lithium ion diffusion. It is concluded that the molten salt synthesis can substantially reduce the calcination temperature and shorten the soaking time.