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In this work, we successfully synthesized porous C/Fe3O4 microspheres by spray pyrolysis at 700ºC with a sodium nitrate (NaNO3) additive in the precursor solution. Furthermore, we studied their electrochemical properties as anode material for Li-ion batteries. The systematic studies by various characterization techniques show that NaNO3 catalyzes the carbonization of sucrose and enhances the crystallization of Fe3O4. Moreover, an aqueous etching can easily remove sodium compounds to produce porous C/Fe3O4 microspheres with large surface areas and pore volumes. The porous C/Fe3O4 microspheres exhibit a reversible capacity of ~780 mAh g–1 in the initial cycles and ~520 mAh g–1 after 30 cycles at a current density of 50 mA g–1. Moreover, a reversible capacity of ~400 mAh g–1 is attainable after 200 cycles, even at a high current density of 500 mA g–1. The wide range of pores produced from the removal of sodium compounds might enable easy electrolyte penetration and facilitate fast Li-ion diffusion, while the N-doping can promote the electronic conductivity of the carbon. These features of porous C/Fe3O4 microspheres led to the improved electrochemical properties of this sample. [ABSTRACT FROM AUTHOR]

• Spherical nanostructured LiCoPO 4 was prepared by spray pyrolysis in air atmosphere. • Citric acid additive in precursor solution inhibited primary particle growth. • Reduced primary particles enhanced electrochemical properties of LiCoPO 4 electrode. • Spherical nanostructured LiCoPO 4 electrode exhibited excellent cell performance. Spherical nanostructured LiCoPO 4 (SN-LiCoPO 4) particles were facilely synthesized by citric acid assisted spray pyrolysis at 600 °C in air atmosphere. The X-ray diffraction pattern of the synthesized LiCoPO 4 samples was indexed to olivine structure with a Pnma space group. Scanning electron microscopy analysis showed that the primary particle size of LiCoPO 4 reduced due to citric acid additive into a precursor solution. This fact might indicate that the citric acid additive restricted the agglomeration and growth of primary particles in a droplet to solid particle conversion process of spray pyrolysis synthesis. The first discharge capacity of SN-LiCoPO 4 electrode was 135 mAh g−1 at 0.05 C in a voltage range of 2.0–5.1 V, corresponding to approximately 81% of its theoretical capacity (167 mAh g−1). Moreover, the rate capability of SN-LiCoPO 4 electrode was superior to that of bare LiCoPO 4 electrode , delivering a discharge capacity of 73 mAh g−1 even at 0.5 C. Cyclic voltammetry and electrochemical impedance spectroscopy data demonstrated that the SN-LiCoPO 4 electrode had lower polarization and faster redox reaction kinetics for the charge and discharge processes. These results were attributed to the reduced primary particle sizes that shortened the lithium ion diffusion pathway during the charge and discharge processes for lithium batteries. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • LiNi 1-x Co x PO 4 (x = 0, 0.2, 0.5, 0.8, 1) solid solutions were prepared. • Nickel substitution by cobalt could improve capacity of LiNiPO 4. • LiNi 1-x Co x PO 4 /C (x = 0, 0.2, 0.5, 0.8, 1) nanocomposites were prepared. • Carbon coating could improve capacity and cyclability of LiNi 1−x Co x PO 4. • The activity of Ni2+/Ni3+ redox couple was discovered for LiNi 0.5 Co 0.5 PO 4 /C sample. Abstract Pure LiNi 1−x Co x PO 4 (x = 0, 0.2, 0.5, 0.8, 1) was synthesized by spray pyrolysis followed by heat treatment. The X-ray diffraction (XRD) patterns of LiNi 1−x Co x PO 4 were indexed to olivine structure with a Pnma space group. The peak shift and variation of lattice parameters suggested that LiNi 1−x Co x PO 4 solid solution was formed. Moreover, LiNi 1−x Co x PO 4 /C (x = 0, 0.2, 0.5, 0.8, 1) nanocomposites were successfully synthesized by a combination of spray pyrolysis and wet ball milling followed by heat treatment. The XRD patterns of all samples were indexed to olivine structure with a Pnma space group. From scanning electron microscopy images, the primary particle sizes of LiNi 1−x Co x PO 4 /C nanocomposites were reduced to the range of approximately 50–100 nm. LiNi 0.5 Co 0.5 PO 4 /C cathode exhibited a higher first discharge capacity and cyclability than those of pure LiNi 0.5 Co 0.5 PO 4. Cyclic voltammetry data demonstrated that reduction peaks of LiNi 0.5 Co 0.5 PO 4 /C cathode occur at 4.44 V and 4.71 V, which were ascribed to Co3+/Co2+ and Ni3+/Ni2+ reduction couples, respectively. Electrochemical impedance spectroscopy data revealed that the LiNi 0.5 Co 0.5 PO 4 /C cathode had a smaller charge transfer resistance, resulting in a faster redox reaction kinetics for the lithium insertion and extraction, due to reduced particle size and introduced conductive carbon. [ABSTRACT FROM AUTHOR]

Electrochemical performances of non-stoichiometric CuS (1.25 ≤ x ≤ 0.625) cathodes prepared by spray pyrolysis and followed annealing were investigated after coating on carbon fiber paper (CFP) and Cu foil current collectors. The chemical composition influence on the electrochemical properties of CuS was noticeably observed on a Cu foil current collector, especially at higher charge-discharge rates. Electrochemical impedance spectroscopy revealed that Cu/S ≈ 3.2 M ratio electrode shows lower interfacial charge transfer resistance ( R ) after 5 cycles at 0.1 C compared with Cu/S ≈ 1.6 M ratio electrode on both current collectors. Accordingly, the electrode with Cu/S ≈ 3.2 M ratio showed the highest discharge capacity of 350 mAh g at 5 C on a Cu foil current collector. The excess of Cu in CuS enhanced electrode utilization with the cycle number and facilitated fast charge transfer. [ABSTRACT FROM AUTHOR]

Carbon impregnated Li 2 FeP 2 O 7 composite was prepared by spray pyrolysis and followed annealing process. The physical and electrochemical properties of prepared samples were investigated. Citric acid was added to the precursor solution as a carbon source for preparing the carbon impregnated Li 2 FeP 2 O 7 composite. X-ray diffraction study identified the phase transformation according to operation temperature and added amount of the carbon source. Cross-sectional morphology observation by SEM with EDS defined layer like carbon distribution in particles. The electrochemical properties of carbon impregnated Li 2 FeP 2 O 7 were evaluated by comparing with a further carbon-coated sample. Despite the relatively less carbon content due to synthesis restriction, it demonstrated similar rate capability with the further carbon coated Li 2 FeP 2 O 7 . Moreover, the carbon impregnated Li 2 FeP 2 O 7 prepared by spray pyrolysis and conventional ball milling process achieved similar capacity while charge current density was different at discharge current rate of 1 C as well as excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Porous nanostructured V 2 O 5 (PN-V 2 O 5 ) was prepared by a facile spray pyrolysis and used as additive to synthesize sulfur/carbon/PN-V 2 O 5 (S/C/PN-V 2 O 5 ) composite by a combination of wet-ball-milling and heat treatment. The meso- and macropores in PN-V 2 O 5 were confirmed by pore size distribution, which provided the favorable space to accommodate sulfur. The X-ray diffraction analysis showed that the crystal structures of S and V 2 O 5 could be preserved below the heating temperature of 160 °C and that high heating temperature (200 °C) will result in reaction between S and V 2 O 5 . The pore size distribution curves of S/C/PN-V 2 O 5 composites revealed that the penetrated S in PN-V 2 O 5 pores mainly occupied the mesopores and macropores, which was further confirmed by a typical cross-sectional PN-V 2 O 5 with Auger analysis. The S/C/PN-V 2 O 5 composite cathode exhibited a discharge capacity of 632 mAh g −1 after 60 cycles at the current density of 100 mA g −1 and the capacity retention of S/C/PN-V 2 O 5 electrode was 27.3% higher than that of S/C electrode, demonstrating a better cycling performance. [ABSTRACT FROM AUTHOR]

Porous nanostructured vanadium pentoxide with mesopores and macropores (PN-V 2 O 5 ) was successfully prepared by spray pyrolysis with an ammonium nitrate additive in a precursor solution, consisting of ammonium metavanadate dissolved in distilled water, and then its cycling ability and rate capability in rechargeable lithium batteries were tested at different current rates in a cut-off potential range of 2.5–4.0 V vs Li/Li + . The PN-V 2 O 5 exhibited a first discharge capacity of 138 mA h g −1 , which corresponds to 93% of its theoretical capacity, and a capacity retention of 86% after 100 cycles at a current density of 100 mA g −1 . Furthermore, it had discharge capacities of 88 and 64 mA h g −1 at 800 and 1200 mA g −1 , respectively. [ABSTRACT FROM AUTHOR]

In this study, stoichiometric Cu 2 S with monoclinic crystal structure with space group P2 1 /c was prepared via spray pyrolysis with followed heat treatment. Its electrochemical properties were investigated after coating on a carbon fiber paper (CFP) current collector and cycling at various cut-off voltages. The reversible stable capacity of about 330 mAh g −1 (98% of its theoretical capacity) exhibited by the cell for 20 cycles at 0.1C and slightly dropped to 311 mAh g −1 after 50 cycles. At higher 1C rate, a discharge capacity of 280 mAh g −1 was retained for 100 cycles with approximately 100% Coulombic efficiency between 1.0-3.0 V. While the gradual capacity decrease is observed with the increase of the discharge cut-off voltage to avoid solid electrolyte interface (SEI) formation during the 1st discharge. The cells showed capacities of 307 and 280 mAh g −1 after the 5th cycle at 0.1C when cycled between 1.1-3.0 V and 1.2-3.0 V, respectively, due to the lowered lithium ion diffusion. Ex situ XRD analysis of the recovered electrodes after cycling with near theoretical capacity allowed discussing the actual reaction mechanism of stoichiometric Cu 2 S with Li + . [ABSTRACT FROM AUTHOR]

Synthesis of stoichiometric copper sulfide (Cu 2 S) was studied by spray pyrolysis (SP) with heat treatment for different Cu/S molar ratios in the starting solution and different synthesis and annealing temperatures. The sample prepared via SP at 400 °C and then annealed at 460 °C for 2 h showed the stoichiometric Cu/S ratio, which was verified by inductively coupled plasma-optical emission spectroscopy. The X-ray diffraction (XRD) peaks of the sample were indexed to the monoclinic structure with space group P 2 1 / c . The electrochemical performance of the stoichiometric Cu 2 S electrode was investigated by a cycle test and differential capacity analysis. The Cu 2 S electrode coated on an Al foil exhibited a first discharge capacity of 335 mAh g −1 at a charge-discharge rate of 0.1 C, which corresponds to 99.4% of its theoretical capacity. However it showed poor reversibility owing to the corrosion of Al foil by Cu. In contrast, the Cu 2 S electrode coated on Cu foil demonstrated stable cyclability at high charge-discharge rates of up to 30 C. Exsitu XRD analysis showed that a phase transformation from the monoclinic Cu 2 S structure with the space group P 2 1 / c to the tetragonal Cu 1.96 S structure with the space group P 4 3 2 1 2 gradually progressed during the initial five cycles. [ABSTRACT FROM AUTHOR]

• Spray pyrolysis with steam oxidation produced C/Fe 3 O 4 microspheres. • C/Fe 3 O 4 microspheres from spray pyrolysis were amorphous-dense. • C/Fe 3 O 4 microspheres after steam oxidation were porous-crystalline. • Optimal electrochemical interfaces of C/Fe 3 O 4 enhanced Li-S battery performance. We used different C/Fe 3 O 4 microspheres such as dense-amorphous and porous-crystalline, prepared by spray pyrolysis with steam oxidation, to clarify the synergetic effect of conductive and adsorptive/catalytic interfaces on the electrochemical properties of Li-S batteries. According to the physical characterizations, the prepared C/Fe 3 O 4 microspheres significantly differ in their surface texture, porosity, and crystal structures. The porous-crystalline C/Fe 3 O 4 microspheres have a wide range of micro-and mesopores to physically adsorb polysulfides and highly accessible Fe 3 O 4 nanoparticles to chemically immobilize them within the electrochemical interfaces and promote their conversion into short-chain sulfides. On the other hand, a densely coated carbon of the dense-amorphous C/Fe 3 O 4 microspheres impedes the chemical interaction between the polysulfides and Fe 3 O 4 nanoparticles. As a result, the porous-crystalline C/Fe 3 O 4 microspheres enhance sulfur utilization and accelerate the redox kinetics of Li–S cells when used as modified separators. These cells exhibit a higher specific capacity of ⁓700 mAh g–1 with a capacity retention of 93% after 200 cycles at 1.0 C. This work demonstrates that high-performance Li–S batteries can be achieved by rationally designing conductive and adsorptive/catalytic interfaces of C/Fe 3 O 4 microspheres. [Display omitted] [ABSTRACT FROM AUTHOR]

Porous nanostructured vanadium pentoxide (V 2 O 5 ) particles were successfully prepared by spray pyrolysis (SP) in a precursor solution with an ammonium nitrate (NH 4 NO 3 ) additive. The correlation between the porous structure and the electrochemical properties of the V 2 O 5 particles was investigated. The porous structure markedly changed upon increasing the concentration of NH 4 NO 3 in the precursor solution from 0 to 0.408 mol L −1 . Pore structure analysis based on N 2 adsorption-desorption isotherm measurements indicated that porous nanostructured V 2 O 5 particles with a pore size of less than 100 nm can be prepared by the novel SP method and that an increase in the NH 4 NO 3 concentration in the precursor solution can enlarge the pores in the V 2 O 5 particles, especially those with a size between 20 and 80 nm. The porous nanostructured V 2 O 5 prepared with an NH 4 NO 3 concentration of 0.272 mol L −1 exhibited a first discharge capacity of 400 mAh g −1 at 20 mA g −1 . The unique porous structure of V 2 O 5 particles significantly enhanced the rate performance and exhibited a first discharge capacity of 180 mAh g −1 at 1200 mA g −1 , which is much higher than that of dense V 2 O 5 particles (70 mAh g −1 ). [ABSTRACT FROM AUTHOR]

A Li 2 FeP 2 O 7 /Carbon (C) nanocomposite was successfully synthesized via a combination of spray pyrolysis and wet ball milling followed by annealing from a precursor solution; in which LiNO 3 , H 3 PO 4 and Fe(NO 3 ) 3 ·9H 2 O were stoichiometrically dissolved into distilled water. Ascorbic acid was added to the precursor solution as a reduction agent. The peaks of the Li 2 FeP 2 O 7 /C nanocomposite obtained by X-ray diffraction analysis were indexed to the monoclinic structure with the space group P 2 1 /c. The Li 2 FeP 2 O 7 /C nanocomposite cathode delivered a first discharge capacity of 100 mAh g −1 at 0.05 C, which corresponded to 91% of its theoretical capacity. After various higher discharge rates from 0.05 to 2 C in the cycle performance test, a discharge capacity of 93 mAh g −1 was achieved at 0.05 C, which showed an excellent capacity retention (93%) after 29 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spray pyrolysis with steam oxidation produced C/Fe 3 O 4 microspheres. • C/Fe 3 O 4 microspheres had wide-range of pores and high-conductive graphitic carbon. • Synergy between porous and conductive carbon enhanced Li-ion battery performances. This work introduces a novel synthesis route for the porous-crystalline C/Fe 3 O 4 microspheres by spray pyrolysis with post oxidation under a steam atmosphere. The dense-amorphous C/Fe 3 O 4 microspheres prepared by spray pyrolysis are firstly annealed at 700 °C for 4 h under 3 %H 2 /N 2 atmosphere to crystallize the amorphous carbon and introduce micro- and meso-pores. The reduced Fe 3 C nanoparticles are then oxidized into highly-crystalline Fe 3 O 4 at 500 °C for 2 h under H 2 O (g) /N 2 atmosphere. The XRD, Raman, XPS, and N 2 sorption analysis confirm the successful formation of C/Fe 3 O 4 microspheres with well-developed porous structure and highly conductive graphitic carbon. The porous-crystalline C/Fe 3 O 4 microspheres demonstrate a higher specific capacity of ∼560 mA h g−1 at a current density of 50 mA g−1 than the dense-amorphous microspheres, which corresponds to 92% of its theoretical value. Moreover, the sample has an improved rate capability (240 mA h g−1 even at 5000 mA g−1) and stable long-term cycling performance due to the synergy between porous structure and graphitic carbon. [ABSTRACT FROM AUTHOR]

A novel preparation route was developed for synthesizing SiO 2 /C nanocomposites through a mechanochemical-assisted sol–gel process combined with a high-energy dry ball milling process. The effect of process parameters, such as milling time, rotation speed and carbon content, on the structure and morphology of SiO 2 /C nanocomposites was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy and transmission electron microscopy with energy-dispersive spectroscopy. It was demonstrated from the physical characterization that the proposed preparation route might be an effective synthesis route for SiO 2 /C nanocomposites consisting of highly dispersed carbon nanoparticles on fine amorphous SiO 2 particles. The electrochemical performance was characterized using Li|1 M LiPF 6 in EC:DMC = 1:1| SiO 2 /C cells in the potential range from 0.01 to 3.0 V versus Li/Li + . The SiO 2 /C nanocomposite prepared under optimized process conditions exhibited a highly stable reversible capacity of 663 mA h g −1 (872 mA h g-SiO 2 −1 ) at a current density of 46 mA g −1 after 30 cycles with no capacity fading. [ABSTRACT FROM AUTHOR]

A Li 2 MnP 2 O 7 /C composite was synthesized by a combination of spray pyrolysis and wet ball milling followed by annealing. The peaks of the Li 2 MnP 2 O 7 /C composite obtained by X-ray diffraction analysis were indexed to the monoclinic structure with the space group P 2 1 /c. Field-emission scanning electron microscopy and transmission electron microscopy together with energy-dispersive spectroscopy verified that the Li 2 MnP 2 O 7 /C composite consisted of agglomerates of Li 2 MnSiO 4 primary particles, and that a thin carbon layer was partially formed on the surface of these agglomerates. The Li 2 MnP 2 O 7 /C composite cathode delivered a first discharge capacity of 72 mA h g −1 at 0.1 C and 60 °C, while the theoretical capacity is 110 mA h g −1 for the Mn 3+ /Mn 2+ redox reaction. The cathode also showed good cycling performance over 15 cycles. [ABSTRACT FROM AUTHOR]

Highlights: [•] Li2MnSiO4/C was prepared by a novel preparation method. [•] Li2MnSiO4/C is agglomerates with primary particles less than 100nm in size. [•] Carbon is partially distributed on the surface of Li2MnSiO4 agglomerates. [•] Li2MnSiO4/C electrode includes only 5wt.% of acetylene black. [•] Li2MnSiO4/C electrode showed a discharge capacity of 225mAhg−1 at 0.05C and 60°C. [ABSTRACT FROM AUTHOR]

Abstract: Olivine structured LiCo1/3Mn1/3Fe1/3PO4/C nanocomposites were prepared by a combination of spray pyrolysis at 300 °C and wet ball-milling followed by heat treatment at 500 °C for 4 h in a 3%H2 + N2 atmosphere. The formation of a solid solution between LiCoPO4, LiMnPO4, and LiFePO4 at this composition was confirmed by X-ray diffraction analysis. Scanning electron microscopy and transmission electron microscopy with equipped energy dispersive spectroscopy verified that the LiCo1/3Mn1/3Fe1/3PO4/C nanocomposites were agglomerates of LiCo1/3Mn1/3Fe1/3PO4 primary particles with a geometric mean diameter of 107 nm and a uniform chemical composition, and carbon was well distributed on the surface of the agglomerates. The LiCo1/3Mn1/3Fe1/3PO4/C nanocomposite cathode exhibited a high discharge capacity of 159 mAh g−1 at 0.05 C in the potential range of 2.0–5.0 V, corresponding to 94% of theoretical capacity. The capacity retention was 87% after 50 cycles at a charge–discharge rate of 1 C. Furthermore, the rate capability test showed that the high capacity still was retained even at 5 C and 20 C rate with 106 and 72 mAh g−1, respectively. [Copyright &y& Elsevier]

Abstract: The combination of emulsion drip combustion at 600 °C and wet ball-milling followed by heat treatment at 500 °C in a N2 + 3% H2 atmosphere was performed for the preparation of LiCoPO4/C nanocomposites. The obtained material consisted of agglomerates of LiCoPO4 primary particles with a geometric mean diameter of 70 nm, which were covered by a thick layer of amorphous carbon. A cell containing the LiCoPO4/C nanocomposites exhibited a discharge capacity of 134 mAh g−1 at a charge-discharge rate of 0.1 C. However, the discharge profile of the LiCoPO4/C nanocomposites had a long tail, which may be due to the limited lithium ion diffusion caused by the thick carbon layer that formed on the LiCoPO4 primary particles. The LiCoPO4/C nanocomposites prepared from a mixture of kerosene and heptane with equal volumes consisted of agglomerates of the primary particles with a geometric mean diameter of 97 nm, which were covered by a thin layer of amorphous carbon with a thickness on the order of 10 nm. Furthermore, they delivered a high energy density of 595 Wh kg−1 at a charge–discharge rate of 0.1 C and exhibited reasonable cyclability, retaining 87% of the initial energy density after 25 cycles. [Copyright &y& Elsevier]

Abstract: LiFePO4/C composites were successfully prepared by emulsion drip combustion in a fluidized bed reactor followed by heat treatment from the precursor solution; LiNO3, Fe(NO3)3·9H2O and H3PO4 were stoichiometrically dissolved in distilled water. The ordered LiFePO4 olivine structure could be obtained after the heat treatment of the as-prepared samples was performed at temperature ranges from 500 to 800°C in N2 +3% H2 atmosphere. It was also confirmed from the transmission electron microscopy (TEM) observation with electron diffraction spectrometry (EDS) that the final samples were LiFePO4/C composites with larger secondary particles. The LiFePO4/C composites were prepared at 600°C and then annealed at 700°C exhibited a first discharge capacity of 93mAhg−1 at a 0.1C rate, which corresponded to 55% of the theoretical capacity. The as-prepared sample at 600°C by the emulsion drip combustion was milled in ethanol by a planetary ball-milling and then annealed at 700°C for 4h in N2 +3% H2 atmosphere. It was clearly seen from scanning electron microscopy(SEM) and TEM images with EDS that the final sample was made up of agglomerates with approximately 100nm primary particles covered with a thin carbon layer. As a result, LiFePO4/C nanocomposites could be successfully prepared by a combination of emulsion drip combustion and wet ball-milling followed by heat treatment. The LiFePO4/C nanocomposites delivered a first discharge capacity of 147mAhg−1 (86% of theoretical capacity) at a 0.1C rate. The capacity retention after 100 cycles for the cell was 98% at a 1C rate. [Copyright &y& Elsevier]

Abstract: Li2FeSiO4/C nanocomposites were synthesized by a novel synthesis route, i.e., a combination of spray pyrolysis and wet ball-milling followed by annealing. The effect of process parameters such as spray pyrolysis temperature, ball-milling time, carbon content in the wet ball-milling process and annealing temperature on the physical and electrochemical properties of Li2FeSiO4/C nanocomposites was investigated. The final sample was identified as Li2FeSiO4 with a P2 1 monoclinic structure by X-ray diffraction analysis. Field-emission scanning electron microscopy and transmission electron microscopy with energy-dispersive spectroscopy verified that the Li2FeSiO4/C nanocomposites are agglomerates of Li2FeSiO4 primary particles with a geometric mean diameter of 65nm and that the carbon was well-distributed on the surface of the agglomerates. A Li2FeSiO4/C nanocomposite sample was used as an electrode material for rechargeable lithium batteries, and electrochemical measurements were carried out by using Li|1M LiPF6 in EC: DMC=1:1| Li2FeSiO4/C cells at room temperature. The Li2FeSiO4/C nanocomposite electrode delivered a first discharge capacity of 154mAhg−1 at 0.05C, corresponding to 93% of the theoretical value. Furthermore, the cycleability and rate capability of the cells were good. [Copyright &y& Elsevier]

Abstract: LiCoPO4/C nanocomposites could be prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment. The effect of spray pyrolysis temperature on physical and electrochemical properties of the LiCoPO4/C nanocomposites was investigated in the range of spray pyrolysis temperature from 200 to 500°C. Single phase LiCoPO4 olivine structure could be identified by X-ray diffraction analysis for all samples. Scanning electron microscopy observation showed that all samples consisted of approximately 100nm primary particles. The LiCoPO4/C nanocomposites were used as a cathode active material for lithium batteries, and the electrochemical tests were carried out using the cell Li|1M LiPF6 in EC:DMC=1:1|LiCoPO4/C at various charge/discharge rates in a cutoff potential between 2.5 and 5.0V. The final LiCoPO4/C nanocomposite sample prepared at a spray pyrolysis temperature of 300°C exhibited the best electrochemical performance mainly due to the largest specific surface area, the smallest primary particle size and a well distributed carbon in the composites. The cells exhibited initial discharge capacities of 134mAhg−1 at 0.05°C, 128mAhg−1 at 1C and 88mAhg−1 at 10C. [Copyright &y& Elsevier]

Abstract: LiCo x Mn1−x PO4/C nanocomposites (0≤ x ≤1.0) were prepared by a combination of spray pyrolysis at 300°C and wet ball-milling followed by heat treatment at 500°C for 4h in 3% H2 +N2 atmosphere. X-ray diffraction analysis indicated that all samples had the single phase olivine structures indexed by orthorhombic Pmna. The lattice parameters linearly decreased with increasing cobalt content, which confirmed the existence of solid solutions. It was clearly seen from the scanning electron microscopy observation that the LiCo x Mn1−x PO4/C samples were agglomerates with approximately 100nm primary particles. The LiCo x Mn1−x PO4/C nanocomposites were used as cathode materials for lithium batteries, and electrochemical performance was comparatively investigated with cyclic voltammetry and galvanostatic charge–discharge test using the Liǀ1M LiPF6 in EC:DMC=1:1ǀLiCo x Mn1−x PO4/C cells at room temperature. The cells at 0.05C charge–discharge rate delivered first discharge capacities of 165mAhg−1 (96% of theoretical capacity) at x =0, 136mAhg−1 at x =0.2, 132mAhg−1 at x =0.5, 125mAhg−1 at x =0.8 and 132mAhg−1 (79% of theoretical capacity) at x =1.0, respectively. While the first discharge capacity increased with the cobalt content at high charge–discharge rates more than 0.5C due to higher electronic conductivity of LiCoPO4 in comparison with LiMnPO4, the cycleability of cell became worse with increasing the amount of cobalt. The existence of Mn2+ seemed to enhance the cycleability of LiCo x Mn1−x PO4/C nanocomposite cathode. [Copyright &y& Elsevier]

Abstract: Spherical LiMnPO4/C composite microparticles were prepared by a combination of spray pyrolysis and spray drying followed by heat treatment and examined as a cathode material for lithium batteries. The structure, morphology and electrochemical performance of the resulting spherical LiMnPO4/C microparticles were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electronic microscopy and standard electrochemical techniques. The final sample was identified as a single phase orthorhombic structure of LiMnPO4 and spherical powders with a geometric mean diameter of 3.65μm and a geometric standard deviation of 1.34. The electrochemical cells contained the spherical LiMnPO4/C microparticles exhibited first discharge capacities of 112 and 130mAhg−1 at 0.05C at room temperature and 55°C, respectively. These also showed a good rate capability up to 5C at room temperature and 55°C. [Copyright &y& Elsevier]

Abstract: LiCoPO4/C nanocomposites could be successfully prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment. X-ray diffraction analysis confirmed that the LiCoPO4/C nanocomposites were well crystallized in an orthorhombic structure with Pmna space group. Scanning electron microscopy and transmission electron microscopy with equipped energy dispersive spectroscopy verified that the LiCoPO4/C nanocomposites were the agglomerates of LiCoPO4 primary particles with a geometric mean diameter of 87nm, and the carbon was well distributed on the surface of the agglomerates. The LiCoPO4/C nanocomposites were used as cathode active materials for lithium batteries, and the electrochemical tests were carried out for the cell Li|1M LiPF6 in EC:DMC=1:1|LiCoPO4/C at various charge–discharge rates. The cells delivered first discharge capacities of 142 and 109mAhg−1 at 0.05 and 20C, respectively. Furthermore, the discharge capacity after 40cycles corresponded to 87% of initial one at 0.1C rate. The excellent rate capability of the cells is mainly due to the well distributed carbon on the LiCoPO4 agglomerates, and a much smaller lithium ion diffusion distance in the electrode. [Copyright &y& Elsevier]

Abstract: LiMnPO4/C nanocomposites could be prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment in the range of spray pyrolysis temperature from 200 to 500°C. The ordered LiMnPO4 olivine structure without any impurity phase could be identified by X-ray diffraction analysis for all samples. It could be also confirmed from scanning electron microscopy and transmission electron microscopy observations that the final samples were the LiMnPO4/C nanocomposites with approximately 100nm in primary particles size. The LiMnPO4/C nanocomposite samples were used as cathode active materials for lithium batteries, and the electrochemical tests were carried out for the cell Li|1M LiPF6 in EC:DMC=1:1|LiMnPO4/C at various charge/discharge rates in three charge modes. As a result, the final sample which was synthesized at 300°C by spray pyrolysis showed the best electrochemical performance due to the largest specific surface area, the smallest primary particle size and a well distribution of carbon. At galvanostatic charge/discharge rates of 0.05C, the cell delivered first discharge capacities of 123 and 165mAhg−1 in correspondence to charge cutoff voltages of 4.4 and 5.0V, respectively. Furthermore, in a constant current–constant voltage charge mode at 4.4V, the cells also exhibited initial discharge capacities of 147mAhg−1 at 0.05C, 145mAhg−1 at 0.1C, 123mAhg−1 at 1C and 65mAhg−1 at 10C. Moreover, the cells showed fair good cycleability over 100 cycles. [ABSTRACT FROM AUTHOR]

Abstract: The olivine structured LiMnPO4/C composites were prepared by a combination of spray pyrolysis and wet ballmilling using different conductive carbons: acetylene black and two types of ketjen black. The ketjen black with a larger specific surface area and dibutyl phthalate absorption number was found to be more preferable compared with other conductive carbons studied in this work. The LiMnPO4/C composite cathode with ketjen black, which has the largest specific surface area, exhibited the largest discharge capacity compared with other LiMnPO4/C composites. The largest discharge capacity delivered by this composite cathode was 166mAhg−1 at 0.05C, which is about 97% of the theoretical value for LiMnPO4. The performance improvement by using this conductive carbon was attributed to its extremely large specific surface area and high ability to absorb the electrolyte, which provide enhanced charge transfer and lithium ion transport in the composite cathode structure. [Copyright &y& Elsevier]

Abstract: A novel preparation technique was developed for synthesizing carbon-coated LiFePO4 nanoparticles through a combination of spray pyrolysis (SP) with wet ball milling (WBM) followed by heat treatment. Using this technique, the preparation of carbon-coated LiFePO4 nanoparticles was investigated for a wide range of process parameters such as ball-milling time and ball-to-powder ratio. The effect of process parameters on the physical and electrochemical properties of the LiFePO4/C composite was then discussed through the results of X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), the Brunauer–Emmet–Teller (BET) method and the use of an electrochemical cell of Li|1M LiClO4 in EC:DEC=1:1|LiFePO4. The carbon-coated LiFePO4 nanoparticles were prepared at 500°C by SP and then milled at a rotating speed of 800rpm, a ball-to-powder ratio of 40/0.5 and a ball-milling time of 3h in an Ar atmosphere followed by heat treatment at 600°C for 4h in a N2 +3% H2 atmosphere. SEM observation revealed that the particle size of LiFePO4 was significantly affected by the process parameters. Furthermore, TEM observation revealed that the LiFePO4 nanoparticles with a geometric mean diameter of 146nm were coated with a thin carbon layer of several nanometers by the present method. Electrochemical measurement demonstrated that cells containing carbon-coated LiFePO4 nanoparticles could deliver markedly improved battery performance in terms of discharge capacity, cycling stability and rate capability. The cells exhibited first discharge capacities of 165mAhg−1 at 0.1C, 130mAhg−1 at 5C, 105mAhg−1 at 20C and 75mAhg−1 at 60C with no capacity fading after 100 cycles. [Copyright &y& Elsevier]

Abstract: A LiMnPO4/C composite cathode was prepared by a combination of spray pyrolysis and wet ball milling. The cathode showed stable performance at various cutoff voltages up to 4.9V. The cutoff voltage increase up to 4.9V allowed the achievement of a high discharge capacity in galvanostatic charge–discharge tests. The discharge capacities of 153mAhg−1 at 0.05C and 149mAhg−1 at 0.1C were achieved at room temperature; the trickle-mode discharge capacities at room temperature were 132, 120 and 91mAhg−1 at 0.1, 1 and 5C discharge rates, respectively. The cell exhibited a good rate capability in the galvanostatic cycling up to 5C discharge rates at both ambient temperature and 50°C. [Copyright &y& Elsevier]

Abstract: A novel preparation technique was developed to synthesize LiFePO4 nanoparticles through a combination of spray pyrolysis (SP) with wet ball-milling (WBM). Using this technique, the preparation of LiFePO4 nanoparticles was investigated for a wide range of process parameters such as ball-milling time and sintering temperature. The effect of process parameters on the physical and electrochemical properties of LiFePO4 was then discussed through analysis using by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), the Brunauer–Emmet–Teller (BET) method, Raman spectroscopy and using an electrochemical cell of Li|1M LiClO4 in EC:DEC=1:1|LiFePO4. LiFePO4 nanoparticles with a geometric mean diameter of 58nm were prepared at a rotating speed of 800rpm and a ball-milling time of 12h in an Ar atmosphere followed by heat treatment at 500°C for 4h in a N2 +3% H2 atmosphere. The sample delivered first discharge capacities of 164 and 100mAhg−1 at charge–discharge rates of 0.1 and 10C in the test cells, respectively. The electrochemical properties of LiFePO4 nanoparticles were strongly affected by the formation of Fe2P, Fe3P and α-Fe2O3 at higher charge–discharge rates. [Copyright &y& Elsevier]

Abstract: Carbon coated LiFePO4 could be successfully prepared by a combination of spray pyrolysis (SP) with planetary ball-milling (BM) followed by heat treatment at 500 °C. SEM and TEM observations revealed that the carbon coated LiFePO4 were much smaller in size than the bare LiFePO4 prepared by the SP followed by heat treatment at 600 °C and the ball-milled bare LiFePO4 prepared by the combination of SP with BM followed by heat treatment at 500 °C. Furthermore, TEM observations also suggested that conductive carbon could be distributed well on the surface of LiFePO4. The electrochemical measurements demonstrated that the carbon coated LiFePO4 could deliver better battery performance in terms of the discharge capacity, cycling stability and rate capability than the bare LiFePO4 and the ball-milled bare LiFePO4. It exhibited first-discharge capacities of 158 mAh g−1 at 0.1C and 114 mAh g−1 at 5C with excellent cycle performances at 25 °C. The cell tested at 60 °C delivered the theoretical capacity (170 mAh g−1) at 0.1C and 78% (133 mAh g−1) of theoretical capacity at 5C, respectively. [Copyright &y& Elsevier]

Abstract: LiFePO4 powders could be successfully prepared from a precursor solution, which was composed of Li(HCOO)·H2O, FeCl2·4H2O and H3PO4 stoichiometrically dissolved in distilled water, by ultrasonic spray pyrolysis at 500°C followed by heat treatment at sintering temperatures ranging from 500 to 800°C in N2 +3% H2 gas atmosphere. Raman spectroscopy revealed that α-Fe2O3 thin layers were formed on the surface of as-prepared LiFePO4 powders during spray pyrolysis, and they disappeared after sintering above 600°C. The LiFePO4 powders prepared at 500°C and then sintered at 600°C exhibited a first discharge capacity of 100mAhg−1 at a 0.1C charge–discharge rate. To improve the electrochemical properties of the LiFePO4 powders, LiFePO4/C composite powders with various amounts of citric acid added were prepared by the present method. The LiFePO4/C (1.87wt.%) composite powders prepared at 500°C and then sintered at 800°C exhibited first-discharge capacities of 140mAhg−1 at 0.1C and 84mAhg−1 at 5C with excellent cycle performance. In this study, the optimum amount of carbon for the LiFePO4/C composite powders was 1.87wt.%. From the cyclic voltammetry (CV) and AC impedance spectroscopy measurements, the effects of carbon addition on the electrochemical properties of LiFePO4 powders were also discussed. [Copyright &y& Elsevier]

A novel technique has been developed to directly produce fine ceramic powders from liquid solution via spray pyrolysis in a fluidized bed reactor (SPFBR). Using this technique the preparation of LiM0.15Mn1.85O4 (M = Mn, Co, Al, and Fe), which are the most promising cathode materials for lithium-ion batteries, has been carried out at a superficial velocity U0 of 0.71 m/s, a reactor temperature T of 800°C, and a static bed height Ls of 100 mm. The as-prepared powders were spherical nanostructured particles that comprised primary particles of a few tens of nanometers in size, and they exhibited a pure cubic spinel structure without any impurities in the XRD patterns. The chemical composition of as-prepared samples showed good agreement with the theoretical values that proved stoichiometric formulae of the compounds. The specific surface area of as-prepared LiM0.15Mn1.85O4 (M = Mn, Co, Al, and Fe) powders decreases with increasing the static bed height in each doping metal, while the crystallite size increases with the static bed height. As a result, the as-prepared powders showed larger crystallite size and smaller specific surface area than those prepared by conventional spray pyrolysis. [ABSTRACT FROM AUTHOR]

Abstract: The deposition of samaria-doped ceria (SDC, Sm0.2Ce0.8O x ) and NiO-SDC thin films on a SDC substrate was studied using the electrostatic spray deposition (ESD) technique. The precursor solution was prepared by dissolving the correct amount of Sm(NO3)3·6H2O, Ce(NO3)3·6H2O and Ni(NO3)2·6H2O into a mixture of ethanol (C2H5OH) and butyl carbitol (C4H9OC2H4OC2H4OH). The surface microstructure of as-deposited thin films was strongly influenced by the substrate temperature, solvent composition and precursor solution. The reticular film of SDC with high porosity could be successfully prepared at the deposition temperature ranging from 300 to 350°C, a precursor solution of 0.005mol/dm3 and a 50vol.% of butyl carbital. The correlations between the surface morphology of as-deposited thin films and the physical properties of precursor solution could be approximately explained by the following equation :where d is the size of sprayed droplet, Q the flow rate of liquid pushed through the jet, ɛ the dielectric constant of liquid, ɛ 0 the electrical permittivity of vacuum, and G(ɛ) is the function of ɛ. The as-deposited thin films were amorphous at the used deposition temperature (350°C). Subsequently, the thermal treatments were done for ranging from 700 to 900°C in air. As the result, the crystal structure transformed into the desired cubic fluorite one after the sample was annealed over 700°C in the as-deposited SDC thin films and 900°C in the as-deposited NiO-SDC thin films, respectively. To confirm the composition of the as-sintered SDC thin films, ICP-OES analysis was studied for the films annealed at 900°C in air for 2h. The observed chemical composition was found to be close to that of the precursor solution within experimental errors. [Copyright &y& Elsevier]

Abstract: Lithium manganese oxide (LiMn2O4) has been synthesized by a spray pyrolysis method from the precursor solution; LiNO3 and Mn(NO3)2·6H2O were stoichiometrically dissolved into distilled water. The synthesized LiMn2O4 particles exhibited a pure cubic spinel structure in the X-ray diffraction (XRD) patterns, however they were spherical hollow spheres for various concentrations of precursor solution. Thus, the as-prepared LiMn2O4 particles were then ground in a mortar and dispersed into distilled water. To make a well dispersed slurry solution, a dispersion agent was also added into the slurry solution. The LiMn2O4 microparticles with a spherical nanostructure were finally prepared by a spray drying method from the slurry solution. The tap density of the LiMn2O4 microparticle prepared by a combination of spray pyrolysis and drying method was larger than that by a conventional spray pyrolysis method. The as-prepared samples were sintered at 750 °C for 1 h in air and used as cathode active materials for lithium batteries. Test experiments in the electrochemical cell Li|1 M LiClO4 in EC:DEC=1:1|LiMn2O4 demonstrate that the sample prepared by the present method is a promising cathode active material for 4 V lithium-ion batteries at high-charge–discharge and elevated temperature operation. The LiMn2O4 compounds by the combination of spray pyrolysis and drying method are superior to that by the conventional spray pyrolysis method in terms of electrochemical characteristics and tap density. [Copyright &y& Elsevier]

Abstract: A series of partially Fe-substituted lithium manganese oxides LiFe x Mn2−x O4 (0≦ x ≦0.3) was successfully synthesized by an ultrasonic spray pyrolysis technique. The resulting powders were spherical nanostructured particles which comprised the primary particles with a few tens of nanometer in size, while the morphology changed from spherical and porous to spherical and dense with increasing Fe substitution. The densification of particles progressed with the amount of Fe substitution. All the samples exhibited a pure cubic spinel structure without any impurities in the XRD patterns. The as-prepared powders were then sintered at 750 °C for 4 h in air. However, the particles morphology and pure spinel phase of LiFe x Mn2−x O4 powders did not change after sintering. The as-sintered powders were used as cathode active materials for lithium-ion batteries, and cycle performance of the materials was investigated using half-cells Li/LiFe x Mn2−x O4. The first discharge capacity of Li/LiFe x Mn2−x O4 cell in a voltage 3.5–4.4 V decreased as the value x increased, however these cells exhibited stable cycling performance at wide ranges of charge–discharge rates. [Copyright &y& Elsevier]

Abstract: Powders of spinel lithium manganese oxide LiMn2O4 and its substituted forms LiMxMn2-xO4 (x=0.05, 0.1, 0.2 and 0.3; M=Al, Cr, Fe and Co) have been successfully synthesized using an ultrasonic spray pyrolysis technique. The effect of Al, Cr, Fe and Co substitution on the powder properties of spinel lithium manganese oxides was examined by X-ray diffraction (XRD), the Brunauer–Emmett–Teller (BET) surface area method, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). All the samples exhibited a pure cubic spinel structure without any impurities in the XRD patterns. The morphology changes from spherical and porous to spherical and dense with increasing metal (Al, Cr, Fe and Co) substitution. The powder properties of lithium manganese oxide, such as geometric mean diameter, crystallite size, and specific surface area, were strongly affected by the composition, x, and substituted metal M (=Al, Cr, Fe and Co) in LiMxMn2-xO4. Spherical, dense particles with the larger crystallite size and smaller specific surface area could be synthesized using ultrasonic spray pyrolysis technique when the manganese was partially substituted by Cr at the composition x≥0.1 in LiCrxMn2-xO4 and by Fe at the composition x≥0.2 in LiFexMn2-xO4, respectively. [Copyright &y& Elsevier]

Abstract: Nanostructured LiM x Mn2−x O4(M=Co and Al, 0≤ x ≤0.3) powders were successfully synthesized by an ultrasonic spray pyrolysis technique from the precursor solutions; LiNO3, Mn(NO3)2·6H2O and Co(NO3)2·6H2O or Al(NO3)3 ·9H2O were stoichiometrically dissolved into distilled water. The product characteristics such as crystallinity, specific surface area, particle morphology and interior structure of particles, were examined with X-ray diffraction (XRD), the Brunauer–Emmet–Teller (BET) method, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), respectively. The chemical composition of the samples was also performed by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The resulting powders were spherical nanostructered particles, which comprised of the primary particles with a few tens of nanometers in sizes. All the samples exhibited a pure cubic spinel structure without any impurities in the XRD patterns, while the surface morphology of as-prepared powders changed from porous to smooth microstructure with the amount of Co or Al substitution. The as-prepared samples were sintered at 750 °C for 4 h in air. However, the particles morphology and pure spinel phase of nanostructured LiM x Mn2−x O4(M=Co and Al)powders did not change after sintering. The as-sintered samples were used as cathode active materials for lithium-ion battery, and electrochemical studies were carried out on the charge/discharge characteristics of the Li/LiM x Mn2−x O4(M=Co and Al) cells at room temperature. [Copyright &y& Elsevier]

Gaps and fragmentation of the superficial lymph node cortex are considered to provide intranodal shunt flow between the afferent and efferent vessels. Using serial sections of 205 nodes obtained from 27 donated cadavers more than 70 years of age, we examined the histological architecture of the abdominal and pelvic nodes in elderly Japanese. Secondary follicles were rare in the specimens. Cortex gaps were, to a greater or lesser degree, found in all nodes. We classified these nodes into three types according to how often the gap occurred. Type 1 nodes, with a relatively complete shield for the afferent lymph, were most frequently found in gastric nodes, whereas type 3 nodes, with numerous gaps, were often observed in the colic, para-aortic and pelvic nodes. The type 3 nodes showed a specific architecture characterized by a fragmented superficial cortex, three-dimensionally assembled cords and a common sinus between them. Primary follicles were located in the assembled cord structures as well as at the superficial cortex. Irrespective of the type, B and T lymphocyte areas were intermingled in the cortex-like areas. The present results reveal region-specific histological heterogeneity in aged human visceral nodes. Due to increased surface areas, the type 3 architecture seemed to accelerate systemic immunity rather than act as a local barrier in the para-aortic and pelvic nodes, which are located centrally along the lymphatic drainage routes. However, thick trabeculae often seemed to develop in the type 3 sinus to decrease nodal function with aging. [ABSTRACT FROM AUTHOR]

The deposition of La1-xSrxCo1-yFeyO3 (0≦x≦0.4 and 0≦y≦1) thin films on a stainless steel or gadolinium-doped ceria substrate was studied using the electrostatic spray deposition (EDS) technique. The precursor solution was prepared by dissolving the correct amount of lanthanum nitrate, strontium chloride, cobalt nitrate and iron nitrate into a mixture of 33 vol.% ethanol and 67 vol.% butyl carbitol. The effect of the process parameters, such as deposition temperature, deposition time and liquid flow rate, on the surface morphology and microstructure of the thin films were examined with scanning electron microscopy (SEM). The deposited La1-xSrxCo1-yFeyO3 thin films were amorphous or nanocrystalline at the used deposition temperature (573 K). Subsequently, the samples were heated at 1173 K for 2 h and were studied using X-ray diffraction (XRD). As a result, the crystal structure of the samples transformed to the desired perovskite phase. The chemical analysis of the thin films was studied by energy dispersion X-ray (EDX) analysis. The observed chemical compositions of the samples were in fair agreement with the ones of the starting precursor solutions. [Copyright &y& Elsevier]

A free-standing SiO 2 /C composite nanofiber mat (FS-SiO 2 /C-CNFM), prepared by electrospinning with heat treatments, is used as a multifunctional interlayer on the cathode side to suppress the polysulfide shuttle effect in lithium–sulfur batteries. The polysulfide adsorption and conversion capabilities of the interlayer are evaluated by a static polysulfide adsorption test and an electrochemical conversion test in an FS-SiO 2 /C-CNFM symmetric cell. The effects of the FS-SiO 2 /C-CNFM on the electrochemical properties of the lithium–sulfur batteries are studied by cyclic voltammetry, galvanostatic charge–discharge cycle tests, and electrochemical impedance spectroscopy. The FS-SiO 2 /C-CNFM interlayer significantly improves the specific capacity, long-cycling stability, and self-discharge behavior of the lithium–sulfur batteries. The cell with the FS-SiO 2 /C-CNFM interlayer has an initial discharge capacity of 1304 mA h g−1 and retains 934 mA h g−1 over 50 cycles at 0.1 C, corresponding to a capacity retention of 72% with 100% Coulombic efficiency. The improved properties are attributed to the suppression of the shuttle effect and the high reutilization of the trapped polysulfides. The adsorption/conversion mechanisms of the polysulfides of the FS-SiO 2 /C-CNFM interlayer are further elucidated from the results of ex situ X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy (EDS) analysis. Image 1 • FS-SiO 2 /C-CNFM was used as an interlayer for Li–S batteries. • The interlayer showed high polysulfide adsorption ability by chemical interactions. • Li–S cell with the interlayer showed good cell performance characteristic. • The interlayer reversibly trapped polysulfides and promoted their conversions. • Mechanisms of polysulfide chemisorption/conversion by SiO 2 /C were elucidated. [ABSTRACT FROM AUTHOR]

• Sulfur-rich CuS 1+x (0 ≤ x ≤ 0.61) was successfully prepared by spray pyrolysis. • CuS1.58 exhibits a high discharge capacity of about 900 mAh g−1 at 0.1C. • CuS 1.58 WBM with 5 wt% carbon exhibits discharge capacity of 1700 mAh g−1 at 0.1C. Copper sulfide is one of the promising cathode materials for the next-generation secondary batteries due to its high electrical conductivity and relatively high capacity. The outstanding cycling performance of sulfur-rich CuS 1+x (0.58 ≤ x ≤ 0.61) cathode material obtained by one-step spray pyrolysis was demonstrated in this work. A simple approach of increasing the sulfur content up to CuS 1.58 achieved ~900 mAh g−1 for 20 cycles at 0.1C. Furthermore, a small addition of carbon (5 wt%) by wet ball milling extremely enhanced discharge capacity to 1200 mAh g−1. [ABSTRACT FROM AUTHOR]

One dimensional SiO 2 /C composite nanofibers were successfully synthesized from precursor solutions with polyvinylpyrrolidone (PVP) as a carbon source by electrospinning with two-step heat treatment, comprising preoxidation at 280 °C in the air followed by annealing at 700 °C for 1 h in a reduced atmosphere. The effects of the preoxidation treatment on the morphology, chemical structure, and electrochemical properties of the synthesized materials were studied by scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, and solid-state nuclear magnetic resonance spectroscopy. The two-step heat treatment had strong positive impacts not only on the morphology but also on the structure and electrochemical performance of the materials. Furthermore, free-standing SiO 2 /C composite nanofiber mats (FS–SiO 2 /C-CNFMs) were prepared from precursor solutions with different PVP concentrations by electrospinning with the two-step heat treatment. The FS-SiO 2 /C-CNFM obtained from the precursor solution with 5 wt.% PVP had a geometric mean diameter of 79 nm and a specific surface area of 642 m2 g−1. It exhibited high initial discharge and charge capacities of 1800 and 984 mA h (SiO 2 -g)−1, respectively, and finally retained a charge capacity of 754 mA h (SiO 2 -g)−1 after 200 cycles with 100% Coulombic efficiency. [ABSTRACT FROM AUTHOR]

Li 2 Fe 1 − x Mn x P 2 O 7 /C (0 ≤ x ≤ 1) composites were prepared using citric acid assisted spray pyrolysis followed by wet ball milling with heat treatment. The citric acid assisted spray pyrolysis was performed by adding citric acid to precursor solutions and the wet ball-milling was done with acetylene black for the as-prepared samples. The chemical compositions of the final samples were confirmed by inductively coupled plasma emission spectrometry (ICP-OES) to be stoichiometric compositions of the desired materials. Furthermore, the formation of Li 2 Fe 1- x Mn x P 2 O 7 solid solutions could be verified by the peak shifts in the X-ray diffraction patterns of the samples and the linear variations of lattice parameters with increasing of x in the Li 2 Fe 1- x Mn x P 2 O 7 /C. The electrochemical performance of Li 2 Fe 1- x Mn x P 2 O 7 /C composites as cathode materials for lithium batteries were evaluated at room and elevated temperatures. The Li 2 Fe 1- x Mn x P 2 O 7 /C composites delivered its theoretical discharge capacity at x = 0, and then its discharge capacity decreases linearly with increasing of x at room temperature. In contrast, it was clearly seen that the electrochemical activity of Li 2 Fe 1- x Mn x P 2 O 7 /C composite was enhanced at an elevated temperature. • Li 2 Fe 1 − x Mn x P 2 O 7 /C composites were obtained by a novel synthesis route. • Formation of Li 2 Fe 1 − x Mn x P 2 O 7 solid solutions could be verified by XRD analysis. • Electrochemical characterizations of Li 2 Fe 1 − x Mn x P 2 O 7 /C composites could be made. • Mn3+/Mn2+ reduction reaction at 4.4 V could be seen in the discharge process. [ABSTRACT FROM AUTHOR]

Pure crystalline Li2MnP2O7/C composite was prepared by spray pyrolysis (SP) followed by annealing (AN) process. Citric acid (CA) was added into the precursor solution as a carbon source to enhance the electrochemical property. The physical and electrochemical properties in conjunction with various synthesis conditions were evaluated. Variation of carbon content, specific surface area, lattice cell volume, and anti-site concentration was revealed along with different preparation conditions of the SP followed by AN process. Electrochemical properties were relevant to various physical properties of samples, and it provided a critical factor to find the most efficient synthesis condition in the SP method. Since incorporated carbon has a significant role in enhancing the electrical conductivity as well as inducing a delicate variation of physical properties, the limitation of incorporated carbon by CA was addressed with associated reaction mechanism. For the sake of exceeding these limitations, further carbon modification with acetylene black was carried out by ball milling (BM) process. The optimal condition of BM process was designated by the resulting of electrochemical property and observing the carbon distribution on the cross section of particles. Li2MnP2O7/C composite prepared under the whole optimal condition delivered the initial discharge capacity of 64 mAh g−1 at a current rate of C/10. The potential of Mn3+/Mn2+ redox couple revealed at 4.3 V versus Li/Li+ upon the discharge process. [ABSTRACT FROM AUTHOR]

Sulfur (S)–carbon (C)–vanadium pentoxide (V 2 O 5 ) composites were prepared by wet ball milling, and their physical and electrochemical properties were evaluated. Firstly, the effect of the carbon content of S–C composite electrodes on their physical and electrochemical properties was investigated. The S–C composite electrode with 60 wt.% S delivers a first discharge capacity of 1077 mAh g −1 . However, its capacity markedly decreases to 606 mAh g −1 after 10 cycles, which corresponds to a capacity fading rate of 47 mAh g −1 per cycle. To improve the electrochemical performance of the S–C composite electrode, carbon was partially replaced by V 2 O 5 . The S–C–V 2 O 5 composite electrode with a composition of 60 wt.%—S, 30 wt.%—V 2 O 5 and 10 wt.%—C exhibits a lower capacity fading rate of 23 mAh g −1 per cycle in the first 10 cycles and better capacity retention than the S–C composite electrode over 50 cycles. [ABSTRACT FROM AUTHOR]

LiCoPO 4 /C nanocomposite fiber mats were successfully synthesized by electrospinning with a two-step heat treatment using nanostructured LiCoPO 4 microparticles prepared by spray pyrolysis. The effects of the pre-oxidation temperature on the physical properties of the synthesized materials were studied. The fiber mats pre-oxidized at 425 °C and subsequently annealed at 700 °C in a N 2 atmosphere contained 7 wt.% carbon and the small agglomerates of LiCoPO 4 nanoparticle were evenly incorporated in carbon fibers with a few hundred nanometers. This fiber mat had a high specific surface area of 338 m2 g–1 and a large meso‑macropore volume of 0.71 cm3 g−1. It was directly used as a free-standing electrode without a binder and a current collector for lithium batteries. The cell exhibited an initial discharge capacity of 115 mAh g–1 at 0.1 C. The effects of SiO 2 coating on the electrochemical properties of LiCoPO 4 /C nanocomposite fiber mats were further studied. Finally, the SiO 2 -coated LiCoPO 4 /C (15 wt.%) nanocomposite fiber mat with 2 wt.% SiO 2 demonstrated superior capacity retention to uncoated ones, and the initial discharge capacities reached 126 mAh g–1 at 0.05 C and 100 mAh g–1 at 1 C, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] One-step synthesis of dense, spherical, nanostructured V2O5 particles was achieved. [•] As-prepared V2O5 consists of primary particles of approximately 100nm size. [•] The electrochemical performance of spherical nanostructured V2O5 was investigated. [•] The potential range affects to the discharge capacity and cyclability of V2O5. [ABSTRACT FROM AUTHOR]

Abstract: Li2MnSiO4/C nanocomposites were synthesized by a novel synthesis route, i.e., a combination of spray pyrolysis and wet ball milling followed by annealing. X-ray diffraction analysis indicated that the peaks of the Li2MnSiO4/C nanocomposites were indexed to the orthorhombic structure in Pmn21 space group. Field-emission scanning electron microscopy and transmission electron microscopy together with energy-dispersive spectroscopy verified that the Li2MnSiO4/C nanocomposites were agglomerates of Li2MnSiO4 primary particles with a geometric mean diameter of 65nm, and that carbon was well distributed on the surface of these agglomerates. Moreover, Li2FexMn1−xSiO4/C (0

Abstract: Nanostructured LiMnPO4 particles could be successfully synthesized by an ultrasonic spray pyrolysis method from the precursor solution; LiNO3, Mn(NO3)2·6H2O and H3PO4 were stoichiometrically dissolved into distilled water. The X-ray diffraction analysis showed that the as-prepared powders which had the desired olivine structure without any impurity phase could be obtained in the reactor temperatures ranging from 500 to 800°C. Carbon coated LiMnPO4 could be prepared from the as-prepared powders by a dry ball-milling followed by heat treatment for 4h in a N2 +3% H2 atmosphere. Transmission Electron Microscopy observation confirmed that a carbon layer was formed on the surface of LiMnPO4 particles, which aimed to enhance the electronic conductivity of the material as well as inhibit the agglomeration during annealing. The carbon coated LiMnPO4 was used as cathode active materials for lithium-ion batteries, and electrochemical performance was investigated using the Li|1M LiClO4 in EC:DEC=1:1|LiMnPO4 cells at room temperature and 55°C. At a charge/discharge rate of 0.05C, the cell exhibited first discharge capacities of 70mAhg−1 at room temperature and 140mAhg−1 at 55°C. Moreover, it showed excellent cycleability even at elevated temperature and a high charge/discharge rate of 2C. [Copyright &y& Elsevier]