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Abstract: Carbon perfectly coated LiFePO4 cathode materials are synthesized by carbon-thermal reduction method using polystyrene (PS) spheres as carbon source. The PS spheres with diameters of 150–300nm used for the pyrolysis reaction not only inhibit the particle growth but also lead to uniform distribution of carbon coating on the surface of LiFePO4 particles. Rate capability and cycling stability of LiFePO4/C with the carbon contents ranging from 1.4wt% to 3.7wt% are investigated at −20°C. The LiFePO4/C with 3.0wt% C exhibits excellent electrochemical capability at low temperature, which delivers 147mAhg−1 at 0.1C. After 100 cycles at a charge–discharge rate of 1C, there is still 100% of initial capacity retained for the LiFePO4/C electrode at −20°C. According to the transmission electron microscope analysis and cyclic voltammetry measurement, this can be attributed to the good carbon coating morphology and optimal carbon coating thickness. [Copyright &y& Elsevier]

Highlights: [•] MnCo2O4 nanowire array is prepared by a fast and facile hydrothermal method. [•] MnCo2O4 nanowire array exhibits noticeable pseudocapacitive properties. [•] The as-prepared nanowire array is also a promising material for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Highlights: [•] Different metal sources are used to prepare Li[Li0.2Mn0.56Ni0.16Co0.08]O2 by sol–gel. [•] Porosity with surface area of 10.09m2 g−1 is only observed when nitrate is used. [•] High discharge capacity of 247.8mAhg−1 is obtained at 1°C for the porous oxides. [•] Porous morphology with good particle contact can efficiently reduce the impedance. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sm2O3 is well coated on Li[Li0.2Mn0.56Ni0.16Co0.08]O2 by simple wet chemical method. [•] The coated sample exhibits high capacity of 234.5mAhg−1 at 1C. [•] Capacity retention of 91.5% is obtained at 1C (200mAg−1) after 80 cycles 25°C. [•] EIS shows the thin Sm2O3 layer mainly reduces the charge transfer resistance. [ABSTRACT FROM AUTHOR]

Abstract: MgO-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 was synthesized via melting impregnation method followed by a solid state reaction. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) show that the MgO layer is well coated on the surface of the layered oxide particles. Although the initial discharge capacity of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 with proper MgO modification decreases compared to the bare one, the 2wt.% MgO coated cathode exhibits the excellent cycling stability with capacity retention of 96.4% at a current density of 200mAg−1 after 100 cycles at room temperature and 94.3% after 50 cycles at 60°C. Electrochemical impedance spectroscopy (EIS) shows that the thin MgO layer mainly reduces the charge transfer resistance and stabilizes the surface structure of active material during cycling. Melting impregnation method is promising for MgO coating to improving the cycling stability of Li-rich layered oxide cathode for Li-ion batteries. [Copyright &y& Elsevier]

Abstract: Ball-like LiMn0.4Ni0.4Co0.2O2 particles composed of flakes were synthesized by a simplified co-precipitation method followed by a solid-state reaction at temperatures of 600–900°C. The relationship between the flake thickness and the electrochemical performance of the layered oxides was investigated in this work. The layered oxide with a flake thickness of 80–100nm synthesized at 800°C has the best electrochemical performance among these cathode materials, especially the rate capability. An initial discharge capacity of 160mAhg−1 was obtained at 5C (1400mAg−1) in the voltage range of 2.5–4.5V, and the capacity retention was 80% after 50 cycles. The excellent rate capability is attributed to the well formed structure, short diffusion distance and good crystallinity. In addition, a detailed study of diffusion coefficient of Li+ was carried out to further understand this material. The value of calculated is in the range of 10−11 to 10−12 cm2 s−1. [Copyright &y& Elsevier]

Abstract: Carbon-coated layered oxide Li1.048Mn0.381Ni0.286Co0.286O2 is prepared by combining a co-precipitation and a direct current magnetron sputtering. TEM images show that the carbon layer is relatively well coated on the surface of oxide particles. The Li1.048Mn0.381Ni0.286Co0.286O2/C composite delivers an initial discharge capacity of 203.2mAhg−1 between 2.5 and 4.5V at 0.1C, and 94% of the initial discharge capacity can be retained after 100 cycles. Moreover, the carbon-coated oxide exhibits noticeable high-rate capacity of 145mAhg−1 at 5C, much higher than the pristine one (103mAhg−1 at 5C). The improved discharge capacity and cycle performance are attributed to the carbon coating, which protects the Li-rich cathode material from reacting with the electrolyte and retarding the incrassation of SEI film on the surface of oxide particles. [Copyright &y& Elsevier]

Abstract: Well-crystallized FeS2 powders are synthesized via solid state reaction. Influence of particle size on electrochemical performances has been conducted. Compared with other anode materials, FeS2 powder with mean particle size of 0.28μm exhibits high coulombic efficiency, initial discharge specific capacity, low polarization and enhanced electrode process kinetics. The enhanced electrochemical properties are attributed to the dense powder packing, better electrical contact and relative stable structure during cycling process. Smaller FeS2 particles (0.078 and 0.071μm) have difficulty in dispersing and mixing with carbon black and binder and less dense packing state, leading to a decrease of reactive contact surface area and poor electrochemical performance. [Copyright &y& Elsevier]

Abstract: Self-organized macroporous tungsten trioxide (WO3) films are obtained by anodic oxidation of DC-sputtered tungsten (W) layers on 10mm×25mm indium tin oxide (ITO)-coated glass. Under optimized experimental conditions, uniformly macroporous WO3 films with a thickness of ca. 350nm are formed. The film shows a connected network with average pore size of 100nm and a pore wall thickness of approximately 30nm. The anodized film becomes transparent after annealing without significant change in macroporous structure. In 0.1M H2SO4, the macroporous WO3 films show enhanced electrochromic properties with a coloration efficiency of 58cm2 C−1. Large modulation of transmittance (∼50% at 632.8nm) and a switching speed of about 8s are also achieved with this macroporous film. [ABSTRACT FROM AUTHOR]