Preparation and characterization of LiNi0.495M0.01Mn0.495O2 (M = Zn, Co, and Y) for lithium ion batteries

Layered structured LiNi0.5Mn0.5O2 and LiNi0.495M0.01Mn0.495O2 (M = Zn, Co, and Y) compounds were prepared by PVP (poly(vinyl pyrrolidone))-assisted sol-gel method, and their structural, morphological, vibrational, transport, and electrochemical properties were characterized by XRD, SEM, FTIR, Raman, AC impedance, and galvanostatic charge and discharge analysis. XRD patterns reveal that doping does not change the crystal structure of the LiNi0.5Mn0.5O2 compound. SEM images show that the average size of the particle is in sub-micron ranges. The AC impedance studies shows an electrical conductivity of ∼2.5 × 10−7 S/cm for the parent compound. The introduction of Zn/Co/Y at equivalent sites increased the electrical conductivity by one order ∼10−6 S/cm. The compound LiNi0.495Co0.01Mn0.495O2 shows the highest electrical conductivity of 2.85 × 10−6 S/cm and delivers a specific discharge capacity of 110 mAh/g at the end of the 25th cycle in the voltage window of 2.5–4.4 V for a current density of 30 mA/g.