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Well-defined orthorhombic LiMnO2 was synthesized using LiOH and γ-MnOOH starting materials at 1000 °C in an argon flow by quenching process. X-ray diffraction (XRD) revealed that the compound showed an orthorhombic phase of a space group with Pmnm (a=2.806 A˚, b=5.750 A˚, and c=4.593 A˚). The prepared compound was composed of particles of about 5–15 μm diameter with a bar-shape and small spherical one of about 1–2 μm. It showed very small initial discharge capacity of about 34 mA h g−1 in the (3+4) V region at room temperature. However, after 12 h grinding, the LiMnO2 delivered 201 mA h g−1 in the first cycle and still delivered 200 mA h g−1 after 50 cycles at room temperature. We found that the initial discharge capacity of LiMnO2 agreed well with its specific surface area by Brunauer, Emmett and Teller (BET) analysis. Especially, the grinding treatment played an important role to activate the lithium insertion–extraction into the LiMnO2 layer in the 3 V region. [Copyright &y& Elsevier]

Layered Li[Ni0.5Mn0.5]O2 materials with high homogeneity and crystallinity were prepared using high speed ball milling. The Li[Ni0.5Mn0.5]O2 electrode delivered a high discharge capacity of 152 mA h g−1 between 2.8 and 4.3 V with excellent cycleability. The TEM analysis showed that the Li[Ni0.5Mn0.5]O2 electrode went through a considerable morphological change without altering its initial layered structure while the electrode retained its initial discharge capacity even after 50 cycles. [Copyright &y& Elsevier]

Abstract: Li1.2(Mn0.32Ni0.32Fe0.16)O2 (LMNFO) nanoparticles with and without a chelating agent (adipic acid) were synthesized by sol–gel method. The supercapacitive behaviors of the synthesized materials as a cathode are evaluated with activated carbon (AC) as the anode in a hybrid supercapacitor (HSC) configuration utilizing a non-aqueous electrolyte. The structural, morphological and electrochemical features of the prepared materials are investigated using X-ray diffraction, scanning electron microscopy and cyclic voltammetry (CV) and charge–discharge studies, respectively. The results demonstrated that the LMNFO nanoparticles prepared with the chelating agent, adipic acid (AA), delivered an enhanced specific discharge capacitance (86Fg−1) and better cycling stability than the native compound. The CV studies also revealed the same conclusions, based on the stronger current response observed during various scan rates between 0 and 3V. Moreover, the AA-LMNFO/AC cell delivered maximum energy and power densities of 36Whkg−1 and 1.67Wkg−1, respectively, with a columbic efficiency of over 99% and excellent rate performance. [Copyright &y& Elsevier]

Abstract: We report the influence of synthesis techniques on the structural and electrochemical behavior of cobalt-free, low-cost and eco-friendly layered type Li1+x (Mn0.4Ni0.4Fe0.2)1−x O2 (0< x <0.4) cathodes for Li-ion batteries. Layered phase, Li1+x (Mn0.4Ni0.4Fe0.2)1−x O2 (0< x <0.4) was prepared by sol–gel, co-precipitation, acetate precipitation and mixed hydroxide method and by subsequent sintering at 700°C under oxygen flow. X-ray diffraction experiments revealed the presence of α-NaFeO2 type structure with space group in the prepared materials. Among the layered phase compounds, material prepared by mixed hydroxide method delivered maximum reversible capacity of 207mAhg−1 at current density of 0.1mAcm−2 between 2 and 4.5V vs. Li with excellent capacity retention characteristics as well. In addition, influence of “x” on electrochemical properties of Li1+x (Mn0.4Ni0.4Fe0.2)1−x O2 (0< x <0.4) were also investigated and such samples were prepared by mixed hydroxide route. [Copyright &y& Elsevier]

Abstract: Cobalt free, eco-friendly layered Li1.2(Mn0.32Ni0.32Fe0.16)O2 compounds were synthesized using the adipic acid assisted sol–gel method. The structure and morphology of the prepared materials were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD results revealed that all of the materials possess a layered α-NaFeO2 structure with space group. The TEM images confirmed the presence of carbon on the surface of the synthesized material. Galvanostatic charge/discharge studies demonstrated that the cyclic performance and rate capability of the materials were improved by the presence of carbon and the crystalline nature of the material. Among the synthesized materials, the sample prepared with 1M adipic acid exhibited not only a high discharge capacity of 160mAhg−1, but also excellent cycling performance with a capacity retention of over 92% after 25 cycles. In addition, electrochemical impedance spectroscopy (EIS) was used to confirm the improvement in the electronic conductivity and the results are discussed in detail. [Copyright &y& Elsevier]