Preparation of Li(Ni0.5Mn1.5)O4 by polymer precursor method and its electrochemical properties

We have prepared a 4.8 V voltage cathode, Li(Ni0.5Mn1.5)O4 using the polymer polyvinylpyrrolidone (PVP) as precursor at temperatures ranging from 700 to 750 °C for 6 h in air. The Rietveld refined X-ray diffraction patterns of Li(Ni0.5Mn1.5)O4 showed a spinel type structure with a lattice parameter value of ∼8.174(2) Å. The Scanning Electron Microscope (SEM) images showed particle size in the range, ∼100–3000 nm. The surface area of the prepared powders was characterized by the Brunauer–Emmett–Teller (BET) technique. Cathodic electrochemical properties were evaluated using cyclic voltammetry (CV) and galvanostatic cycling (GC) in the range 3.5–5.0 V vs. Li/Li+ at ambient temperature. CV studies showed a minor peak at ∼4.0 V due to the Mn3+/4+ redox couple, and main anodic/cathodic peaks at 4.75/4.6 V and 4.8/4.7 V corresponding to the Ni2+/4+ redox couples. The GC studies were carried out at the current rates (C/4.5) 30 mA g−1 and (C/1.2) 120 mA g−1, at room temperature. The reversible capacities of all samples prepared at 700–750 °C are in the range, 92–130 (±3) mAh g−1 at the end of 15th cycle. Impedance studies were carried out on a selected cell.

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► Li(Ni0.5Mn1.5)O4 cathode (4.8 V) material prepared by polymer precursor method at a temperature range, 700–750 °C in air.
► Electrochemical studies on nano-Li(Ni0.5Mn1.5)O4 showed a reversible capacity (charge) of 120 (±3) mAh g−1 at a end of 40th cycle at a current rate of 120 mA g−1.
► The cyclic voltammetry studies showed a minor peak at ∼4.0 V, and main anodic/cathodic peaks at ∼4.75/4.6 V and ∼4.8/4.7 V vs. Li/Li+.
► Electrochemical impedance studies were carried out on selected cell.