Nazario-Naveda, Renny R.

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    High energy density xLi2MnO3-(1−x)LiMn0.5Ni0.5O2 cathode system for lithium-ion rechargeable batteries
    (2013) Nazario-Naveda, Renny R.; Tomar, Maharaj S.; College of Arts and Science - Science; Castellanos, Dorial; Lysenko, Sergiy; Department of Physics; Quiñones, Wilfredo
    In this work xLi2MnO3-(1-x)LiNi0.5Mn0.5O2 (x = 0.3 and 0.5) layered cathode materials were synthesized by the co-precipitation route. The synthesized powders were annealed at 950 °C for 12 h in air to get the desired structure. The synthesized materials were structurally characterized using X-Ray Diffraction (XRD) and Raman Spectroscopy; they show the formation of structures with two phases corresponding to both space group R3m rhombohedral LiMO2 structure and space group C2/m monoclinic Li2MnO3 structure. Morphological studies with Scanning Electron Microscopy (SEM) show highly dense particle agglomerations, the particle size is 0.5 to 2 μm, and agglomerations around 10-20 μm. X-Ray Photoelectron Spectroscopy (XPS) confirms the presence of the Mn in the 4+, Ni in the 2+ and O in the 2- oxidation states. To study the electrochemical behaviour, coin cells were fabricated inside an Argon filled glove-box using a cathode, prepared from the synthesized material, LiPF6 dissolved in Ethylene Carbonate (EC) and Dimethyl Carbonate (DMC) in 1:1 wt ratio as electrolyte and Li foil as anode. Coin cells were electrochemically characterized using Charge-Discharge profiles, Differential Capacity and Electrochemical Impedance Spectroscopy (EIS). Results show the highest capacity for the composite cathode with x = 0.5. Performance at high temperature and MgO coating were also studied, showing an improvement in the electrochemical behaviour.