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Abstract: Spherical LiNi0.5Mn1.5O4 material with a core–shell structure is synthesized by a urea-assisted hydrothermal method followed by heat treatment with LiOH at high temperature. After the process of hydrothermal treatment, the carbonate precursor with a concentration gradient is produced, in a single spherical particle, the content of Ni in the surface is higher than that in the center while Mn has a reversal trend. LiNi0.5Mn1.5O4 synthesized through the hydrothermal route has a great improvement in cycling stability at elevated temperature and rate capability. The capacity retention can maintain at 95% after 30 cycles at 55 °C. Furthermore, it can deliver a discharge capacity of 118 mAh g−1 at a high rate of 10 C at room temperature. Such excellent electrochemical properties of LiNi0.5Mn1.5O4 can be ascribed to its unique core–shell structure and nano-size particle. [Copyright &y& Elsevier]

Abstract: The Li1.2−x Na x Ni0.13Co0.13Mn0.54O2 (0≤ x ≤0.1) cathode materials have been synthesized by a solid-state reaction method. The effects of the Na+ contents on the structure, surface components and electrochemical performance are studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. The XRD data indicate that the Li1.2−x Na x Ni0.13Co0.13Mn0.54O2 samples evolve from a sole layered structure (0≤ x ≤0.02) to a mixture of Na+-contained layered structure (0.02< x ≤0.1), which would transform into the single layered structure after the initial charge and discharge process. XPS data demonstrate that some of the Na+ ions could be reversibly de-/re-intercalated for the Li1.2−x Na x Ni0.13Co0.13Mn0.54O2 materials. An electrochemical test reveals that a small amount of Na+ (x ≤0.02) in the Li1.2−x Na x Ni0.13Co0.13Mn0.54O2 materials can significantly increase the rate capacity, yet the capacity retention becomes worse. We also find that the capacity retention increases with the Na+ contents. [Copyright &y& Elsevier]

A series of (1−x)LiMnPO4·xLi3V2(PO4)3/C (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1) composites cathode materials are successfully synthesized by solid-state method. The structures and properties of the composites have been studied with X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental mapping, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS) and electrochemical measurements. XRD results reveal that the composites comprise Li3V2(PO4)3 phase and LiMnPO4 phase with a small amount of LiVP2O7 impurity. The electrochemical measurement results show that the ratios of LiMnPO4 to Li3V2(PO4)3 are correlated with the electrochemical performances of the composite materials. Among these composites, the 0.6LiMnPO4·0.4Li3V2(PO4)3 exhibits the best electrochemical performance, it can deliver specific capacity of 154 mA h g−1 at 0.05 C charge–discharge rate. [ABSTRACT FROM AUTHOR]