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Abstract: Lithium rich manganese oxide based materials are emerging as possible high energy density cathode materials for lithium ion batteries. In the present research, we have investigated the first charge/discharge profile behavior of Li1.2Ni0.175Co0.1Mn0.52O2 via in situ Raman spectroscopy. X-ray diffraction studies confirm the presence of cation ordering in the transition metal layers. Scanning electron microscopy shows the homogeneous distribution of highly dense spherical agglomerates of ∼5 μm size. Steady decrease in impedance up to ∼4.5 V followed by a less steep increase as the cell voltage traversed the first charge cycle has been confirmed by electrochemical impedance spectroscopy. Raman spectroscopy shows that the extraction of lithium takes place from both the transition metal layers as well as lithium layers in the voltage range of 4.1–4.4 V. The oxygen removal becomes severe in the voltage range of 4.55–4.6 V, after which the diffusion of the transition metal ions to the vacant sites takes place. [Copyright &y& Elsevier]

Abstract: Li(Ni0.8Co0.1Mn0.1)O2 cathode materials were synthesized by solid-state reaction route. Single-phase layer structure with hexagonal unit cell having symmetry was obtained and the average particle size was around 6μm. Electrochemical studies showed single redox reaction and a maximum charging capacity of ∼140mAhg−1 was obtained. Ex situ structural studies by X-ray diffraction and Raman scattering at various stages of charging and discharging showed that the host layered structure is maintained throughout the electrochemical lithiation–delithiation processes in the 3–4.5V range with systematic change in the lattice parameters. First discharge capacity was 132mAhg−1 and the capacity retention was ∼86% after 20 charge–discharge cycles. [Copyright &y& Elsevier]

Abstract: LiMn1.5Ni0.5O4 cathode material was prepared by sol–gel method and annealed at 850°C for 15h. The prepared powder was coated with ZnO by dissolving zinc acetate in methanol and LiMn1.5Ni0.5O4 powder was mixed in this solution followed by the continuous stirring for 4h. The LiMn1.5Ni0.5O4 and ZnO-coated LiMn1.5Ni0.5O4 powder was structurally characterized using X-ray diffraction and scanning electron microscopy (SEM). The coin cell was fabricated using ZnO-coated LiMn1.5Ni0.5O4 as cathode materials, LiPF6, dissolved in ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1 wt ratio) as electrolyte, and Li foil as anode. It was found that ZnO-coated LiMn1.5Ni0.5O4 cathode materials had the initial discharge capacity of about 146mAhg−1. The discharge capacity retention after 50 cycles was found to be nearly 97%. [Copyright &y& Elsevier]

Abstract: Spinel powders of LiMn1.99Nd0.01O4 have been synthesized by chemical synthesis route to prepare cathodes for Li-ion coin cells. The structural and electrochemical properties of these cathodes were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, cyclic voltammetry, and charge-discharge studies. The cyclic voltammetry of the cathodes revealed the reversible nature of Li-ion intercalation and deintercalation in the electrochemical cell. The charge-discharge characteristics for LiMn1.99Nd0.01O4 cathode materials were obtained in 3.4–4.3V voltage range and the initial discharge capacity of this material were found to be about 149mAhg−1. The coin cells were tested for up to 25 charge-discharge cycles. The results show that by doping with small concentration of rare-earth element Nd, the capacity fading is considerably reduced as compared to the pure LiMn2O4 cathodes, making it suitable for Li-ion battery applications. [Copyright &y& Elsevier]

Abstract: Phase pure LiMn1.5Ni0.5O4 powders were synthesized by a chemical synthesis route and were subsequently characterized as cathode materials in a Li-ion coin cell comprising a Li anode and lithium hexafluorophosphate (LiPF6), dissolved in dimethyl carbonate (DMC)+ethylene carbonate (EC) [1:1, v/v ratio] as electrolyte. The spinel structure and phase purity of the powders were characterized using X-ray diffraction and micro-Raman spectroscopy. The presence of both oxidation and reduction peaks in the cyclic voltammogram revealed Li+ extraction and insertion from the spinel structure. The charge–discharge characteristics of the coin cell were performed in the 3.0–4.8V range. An initial discharge capacity of ∼140mAhg−1 was obtained with 94% initial discharge capacity retention after 50 repeated cycles. The microstructures and compositions of the cathode before and after electrochemistry were investigated using scanning electron microscopy and energy-dispersive analysis by X-ray analysis, respectively. Using X-ray diffraction, Raman spectroscopy and electrochemical analysis, we correlated the structural stability and the electrochemical performance of this cathode. [Copyright &y& Elsevier]