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Abstract: Spherical porous tin oxide was fabricated via a spray pyrolysis technique. TEM revealed that the primary SnO2 crystals had an average size of 5–10nm. Good interconnection between SnO2 crystals is also observed. The electrochemical measurements showed that the spherical porous SnO2 samples have excellent cyclability, which can deliver a reversible capacity of 410mAh/g for up to 50 cycles as a negative electrode for lithium batteries. Our approach for enhancing the structural stability of tin oxide is to incorporate spherical porous structures as a buffer zone to alleviate the volume expansion of the tin oxide anode during lithiation/delithiation. [Copyright &y& Elsevier]

Abstract: Phase evolution of YBa2Cu3O7−δ (YBCO) thin films prepared by a newly-developed fluorine-free sol–gel method were studied by combined use of in situ high temperature optical microscope observation and X-ray diffraction. The reaction sequences associated with yttrium, barium and copper in this route were determined respectively. It was found that the reactions that take place were strongly dependent on the experimental conditions such as water partial pressure. The formation of YBCO started around 710°C and continued up to 800°C for about 15min. The formation mechanism of YBCO was found to be dependent on the barium containing phases, which were controlled by the experimental conditions. The formation of a- and c-axes oriented YBCO grains was also found to be governed by the processing reactions. [Copyright &y& Elsevier]

Abstract: LiFePO4 is a promising environmentally friendly and low cost alternative cathode material for use in lithium-ion batteries. The most common materials production process used to manufacture LiFePO4 is solid-state synthesis which entails several grinding and recalcination steps, occurring over many hours. We report on the synthesis of crystalline LiFePO4 in only 10min via a versatile process of Electric discharge assisted mechanical milling (EDAMM). Preliminary electrochemical testing of the synthesized powder demonstrates good capacity and excellent cyclability. The EDAMM technique offers an exciting opportunity to synthesize a range of new and existing materials to be used in a variety of energy storage applications that include rechargeable lithium batteries, hydrogen fuel cells, and supercapacitors. [Copyright &y& Elsevier]

Abstract: Novel ionic liquids (ILs) were used to prepare carbon nanotube (CNT) supported platinum catalysts for the first time. The CNTs were pretreated in acid to get functional groups to promote the adherence of Pt nanoparticles. Ionic liquids added to the reaction system are suggested to contribute to the formation of homogeneous small Pt nanoparticles and to suppress the agglomeration of CNTs. The Pt/CNT electrocatalyst has a fairly homogeneous dispersion of Pt particles with small particle sizes. The electrochemical performance of the Pt/CNT electrocatalysts for PEM fuel cells was studied by cyclic voltammetry measurements. The results show that the ionic liquid has a significant impact on the surface of the as-prepared CNTs and that there is a strong interaction between ionic liquids and CNTs. [Copyright &y& Elsevier]

Abstract: “Free-standing” single wall carbon nanotube (SWNT) papers have been synthesised by simple filtration method via positive pressure. A conventional SWNT slurry coated electrode was fabricated to compare with the SWNT papers. The results show that the capacity of the “Free-standing” electrode was slightly lower than that of the conventional electrode, but the “Free-standing” electrode was produced without any binder, and metal substrate, so that the weight of electrode was reduced significantly. On the other hand, the procedures for SWNT electrode preparation were simplified, so the cost of the manufacturing could be reduced. [Copyright &y& Elsevier]

Abstract: Carbon-enriched Li0.98Mg0.02FePO4 compounds were prepared by a novel modified solid-state reaction method Citric acid added to the precursors works as a particle size growth inhibitor as well as a carbon source. Electrochemical evaluation of the Li0.98Mg0.02FePO4 reveals a lithium insertion plateau around 3.4 V vs. Li together with a specific capacity of over 160mAh/g at the C/20 rate. Differential capacity data confirm the two-phase nature of the insertion reactions as well as outstanding ionic reversibility. [Copyright &y& Elsevier]

Abstract: A series of polypyrrole-LiFePO4 (PPy-LiFePO4) composites were synthesised by polymerising pyrrole monomers on the surface of LiFePO4 particles. AC impedance measurements show that the coating of polypyrrole significantly decreases the charge-transfer resistance of LiFePO4 electrodes. The electrochemical reactivity of polypyrrole and PPy-LiFePO4 composites for lithium insertion and extraction was examined by charge/discharge testing. The PPy-LiFePO4 composite electrodes demonstrated an increased reversible capacity and better cyclability, compared to the bare LiFePO4 electrode. [Copyright &y& Elsevier]

Abstract: Carbon coated lithium iron phosphates were prepared by a carbon aerogel synthesis process, through which LiFePO4 particles were embedded in amorphous carbon. The carbon coating effect can significantly enhance the electronic conductivity of LiFePO4. The electrochemical properties of the as-prepared LiFePO4 cathode materials were systematically characterised. The carbon coated LiFePO4 cathode demonstrated a high capacity and stable cyclability. [Copyright &y& Elsevier]

Abstract: Nanosize silver and tin dioxide powders were synthesised by a novel reverse micelle technique. The reverse micelles were formed from a microemulsion of organic solvents, water based salts and surfactants. The spherical nanosize Ag powders were formed via in situ reduction. The tin hydroxide precipitates were formed in reverse micelles and converted to tin dioxide nanopowders after heat treatment. The Ag and SnO2 powders have a particle size in the range of 20–50nm. The as-prepared nanosize Ag and SnO2 nanopowders were used in lithium-ion cells for lithium storage. [Copyright &y& Elsevier]

Abstract: In this paper, we report on a series of SnO2-carbon nano-composites synthesized by in situ spray pyrolysis of a solution of SnCl2·2H2O and sucrose at 700°C. The process results in super fine nanocrystalline SnO2, which is homogeneously distributed inside the amorphous carbon matrix. The SnO2 was revealed as a structure of broken hollow spheres with porosity on both the inside and outside particle surfaces. This structure promises a highly developed specific surface area. X-ray diffraction (XRD) patterns and transmission electron microscope (TEM) images revealed the SnO2 crystal size is about 5–15nm. These composites show a reversible lithium storage capacity of about 590mAhg−1 in the first cycle. The discharge curve of the composite indicates that lithium is stored in crystalline tin, but not in amorphous carbon. However, the conductive carbon matrix with high surface area provides a buffer layer to cushion the large volume change in the tin regions, which contributes to the reduced capacity fade compared to nonacrystalline SnO2 without carbon. [Copyright &y& Elsevier]

Abstract: Co3O4 has shown acceptable electrochemical properties as the anode material of Li secondary batteries. In detail, its capacity reached about 700mAh/g, twice as high as graphite, and 93.4% of initial capacity was retained after 100 cycles. EIS (electrochemical impedance spectroscopy) analyses revealed that after the 1st cycle, the insertion or extraction of Li ions in Co3O4 can occur homogeneously and reversibly (randless-like behavior, homogeneous mixture: Co+Li2O (in the state of Li insertion), Co3O4 (in the state of Li extraction)). In fact, the coulombic efficiency of Co3O4 was almost 100% except for the 1st cycle. According to P. Poizot''s research on several kinds of transition metal oxides, such as Co3O4, CoO, NiO, etc., a small Li2O particle size and catalytic activity of the transition metal are expected to decrease the binding energy of Li2O tremendously. As a result, Li2O should be easy to decompose, and transition metal oxides should be able to charge or discharge reversibly by formation or decomposition of Li2O. However, this assumption has never been confirmed by experimental results. In our results, the CV (cyclic voltammogram) of a Li2O–Co mixture shows much larger oxidation and reduction peaks than that of Li2O. Based on XRD analyses, oxidation and reduction in the CV of Li2O correspond, respectively, to the decomposition and formation of Li2O. So, it can be asserted that Co addition to Li2O facilitates decomposition and formation processes in Li2O and that the catalytic effect of the transition metal must be one of the main causes that make Li2O form or decompose repeatedly. [Copyright &y& Elsevier]

Abstract: For the first time, carbon-mixed LiFePO4 (LFP) cathode materials have been prepared by spray solution technology. Nominal addition of 15 or 20wt.% C was used in order to simulate the industrial practice for preparation of electrode materials. The prepared powders consist of a single LiFePO4 phase: small crystallites with a highly developed surface area, beneficial for the surface electrochemical processes limited by the low Li diffusion. The combination of spray technology and carbon addition increased the specific surface area above 20m2/g at a relatively high sintering temperature (700°C). The initial discharge capacity was up to 140mAh/g compared to 125mAh/g for conventionally prepared (using a solid state reaction) LiFePO4 electrode materials. [Copyright &y& Elsevier]

Abstract: Stoichiometric and non-stoichiometric Mg-doped lithium iron phosphates were synthesised via spray-pyrolysis, followed by sintering at high temperature for crystallization. The spray pyrolysis process allows the homogeneous mixing of the ingredient reactants at atomic level. The electronic conductivities of the Mg-doped lithium iron phosphates have been drastically improved by 4 orders of magnitude, comparing to the undoped LiFePO4. The electrochemical properties of as-prepared lithium iron phosphates were systematically measured by cyclic voltammetry and constant current charge/discharge cycling tests. [Copyright &y& Elsevier]

Abstract: Spherical LiNi0.75Co0.25O2 compounds were synthesized by sintering spherical Ni0.75Co0.25(OH)2 and LiOH·H2O precursors at various temperatures in an oxygen atmosphere. A pure phase LiNi0.75Co0.25O2 could be identified. SEM observation showed that the LiNi0.75Co0.25O2 particles are spherical in shape and are composed of many small crystals. Magnetic susceptibility measurements reveal that the spherical LiNi0.75Co0.25O2 compounds have a more ordered layered structure than that of non-spherical LiNi0.75Co0.25O2. The spherical LiNi0.75Co0.25O2 cathodes demonstrated a stable electrochemical performance in lithium-ion cells with a high reversible capacity of 167mAh/g and good cyclability. [Copyright &y& Elsevier]

Polycrystalline MgB2 samples with addition of 0–10 wt% powders of SiC, Si and C were prepared by an in situ reaction process. The phases, microstructures, and flux pinning were characterized by XRD, TEM, and magnetic measurements. It was observed that the samples doped with nano-sized SiC have best pinning performance, while nano-Si or nano-C powders showed a similar improved field dependence of the critical current over a wide temperature range compared with both undoped samples and samples doped with coarse SiC and Si powders. Both magnetic and transport Jc were as high as 3000–20,000 A/cm2 in 8 T at 5 K, one or two orders of magnitude higher than for undoped MgB2. Tc only dropped 2 K and remained unchanged with high doping levels for these doped samples. X-ray diffraction results indicated that Si and SiC had reacted with Mg to form Mg2Si. Neutron diffraction and Rietveld analysis showed no evidence of Si doping into the lattice in the Si doped MgB2 samples. Nano-particle inclusions, such as Mg2Si, precipitates of MgO, unreacted nano-particles observed using TEM are proposed to be responsible for the enhancement of flux pinning in high fields. A strong effect of sample size on magnetic Jc(H) was also observed for bulk MgB2. [Copyright &y& Elsevier]

Nanostructured Si–C composite materials were prepared by dispersing nanocrystalline Si in carbon aerogel and subsequent carbonization. Through this process, nanosize Si was homogeneously distributed in a carbon matrix. The Si–C composites exhibit a reversible lithium storage capacity of 1450 mA h/g when used as anodes in lithium-ion cells. The nanostructured Si–C composite electrodes demonstrated good cyclability. The Si–C composites could provide a novel anode material for lithium-ion batteries. [Copyright &y& Elsevier]

By varying the synthetic temperature and time, Co3O4 with highly optimized electrochemical properties was obtained from the solid state reaction of CoCO3. As a result, Co3O4 showed a high capacity around 700 mAh/g and stable capacity retention during cycling (93.4% of initial capacity was retained after 100 cycles). However, its initial irreversible capacity reached about 30% of capacity. Several phenomenological examinations in our previous results told us that the main causes of low initial coulombic efficiency, that is, large initial irreversible capacity, were solid electrolyte interphase (SEI) film formation on surface and incomplete decomposition of Li2O during the first discharge process. SEI film formation cannot be restrained without the development of a special electrolyte, and there has been little research on the proper electrolyte composition, whereas in our research, Ni had the catalytic activity to facilitate Li2O decomposition. Thus, in order to improve the low initial coulombic efficiency of Co3O4 (69%), Ni was added to Co3O4 using two methods like physical mixing and mechanical milling. When adding the same amount of Ni, the mechanical milling showed the improvement in initial coulombic efficiency, 79%, but physical mixing had no effect. Finally, when the charge–discharge mechanism of Co3O4 was considered and the morphologies of Ni–Co3O4 mixture obtained by physical mixing and Ni–Co3O4 composite prepared by mechanical milling were compared, it was revealed that the initial coulombic efficiency of Ni–Co3O4 composite depends on the contact area between the Ni and the Co3O4. [Copyright &y& Elsevier]

We present order-of-magnitude conductivity data for “carbon-included” lithium iron phosphate (LFP) powders lightly pelletised as used as cathodes in Li-ion batteries. The powders were synthesised by a spray pyrolysis method, with a short ameliorating sinter to optimise phase purity. Carbon was introduced into the materials by adding stoichiometric amounts of sucrose into the starting ingredients. We obtained X-ray diffraction patterns and electrical conductivity estimates for carbon contents of between 0 and 31 wt.%. The resultant conductivities spanned almost seven orders of magnitude. [Copyright &y& Elsevier]

Layered Li[Li0.3Cr0.1Mn0.6]O2 cathode material with a hexagonal structure was synthesized by a solid-state reaction. The structural changes of this material were studied using a synchrotron-based in situ X-ray diffraction (XRD) technique during charge/discharge cycles. The results of in situ X-ray diffraction indicated that the layer structure and the hexagonal symmetry of this material were preserved through the phase transition between H1 and H2 during the charge/discharge cycling. When cycled in the voltage range of 2.0–4.5 V, the changes in lattice parameters a and c are smaller than those for the LiNiO2 layered material. When charged to a high voltage at 5.1 V, the hexagonal phase H3, which is commonly formed at voltages higher than 4.3 V in LiNiO2 with a very short c-axis, is not observed in the Li[Li0.3Cr0.1Mn0.6]O2 cathode, indicating a possible high thermal stability in the fully charged state. Cyclic voltammograms show a single pair of oxidation and reduction peaks, consistent with a reversible phase transition between H1 and H2 observed from the in situ X-ray diffraction data. [Copyright &y& Elsevier]

The flux dynamics of a (Tl,Pb)(Sr,Ba)2Ca2Cu3Oy single crystal have been investigated by means of magnetic relaxation measurements, with the applied field parallel to the c-axis. A power law dependence of the activation energy on the current density for fields less than 2 T over the temperature range 15–45 K has been observed, consistent with three-dimensional large bundle vortex creep. For intermediate fields (2–3 T), the flux dynamics are dominated by plastic vortex creep, while for fields higher than 3 T over the temperature range 16–46 K, the vortex glass scaling approach implied that a two-dimensional vortex structure is unlikely for fields less than 5 T. [Copyright &y& Elsevier]

LiTi2(PO4)3 with a Na+ superionic conductor (NASICON)-type structure is prepared by a two-step solid-state reaction. X-ray diffraction (XRD) confirms that the LiTi2(PO4)3 compound has a NASICON structure, i.e. rhombohedral (space group: R3c). It is found that lithium can be electrochemically inserted into the LiTi2(PO4)3 structure, with a maximum intake of 5.2 mol of lithium per mole of LiTi2(PO4)3 compound, and that [PO4] tetrahedra can participate in the redox reaction. This corresponds to a lithium-storage capacity of 360 mAh g−1. The kinetic parameters of lithium insertion in LiTi2(PO4)3 NASICON are determined by means of ac impedance technique. The charge-transfer resistance (RCT) and exchange current density (i0) are invariable regardless of the state of lithium insertion. This is associated with the unique structure characteristics of the NASICON skeleton. By contrast, the diffusion coefficient, DLi of lithium varies with the state of lithium insertion. The value of DLi is in the range 1.4×10−11 to 1.2×10−9 m2 s−1, which is much higher than for other intercalation materials. [Copyright &y& Elsevier]

A new manufacturing technique for positive plates for valve-regulated lead–acid batteries has been developed. This involves a novel paste-preparation method which employs hydrogen peroxide to replace the traditionally used sulfuric acid. After pasting, the plates can be assembled into groups and placed directly into a battery case. Formation can then be performed without the plates undergoing the conventional curing process. Such a non-curing process could reduce production time and costs. More importantly, the resulting plates provide good flexibility which is particularly suitable for spirally-wound battery designs. [Copyright &y& Elsevier]

Magnetic hysteresis and magnetic relaxation measurements have been performed to study vortex pinning behaviors for pure, Fe doped and heavily Pb doped Bi2212 single crystals. Unlike pure and Fe doped Bi2212 crystals, heavily Pb doped crystal showed strong vortex pinning behavior. We interpret the strong pinning in heavily Pb doped Bi2212 single crystals as arising from the improved Josephson coupling in Bi2212 single crystal after heavy Pb doping. In heavily Pb doped single Bi2212 crystals, H[sub dis](T) was observed to decrease with increasing T. Here, H[sub dis] (T) is an order-disorder field that separates a weakly elastically disordered vortex lattice from a plastically disordered vortex solid. However, in pure and Fe doped Bi2212 single crystals, H[sub dis](T) was observed to be temperature independent. We also report a significant shift of T[sub CR], a crossover temperature separating two pinning regimes, toward higher temperatures with heavy Pb doping of Bi2212 single crystals. On the other hand T[sub CR] did not shift with Fe doping of Bi2212 single crystals. It is argued that the temperature dependence of H[sub dis] (T) and the shift of T[sub CR] in heavily Pb doped Bi2212 crystals was related to the enhanced c-axis conductivity caused by the Pb situated between the CuO[sub 2] layers and imposing a 3D characteristic on the vortex lattice. [ABSTRACT FROM AUTHOR]

LiCoO2 cathode materials have been prepared by a spray-drying technique. The stoichiometry of the materials, their morphology, and the phase composition and electrochemical performance have been studied. The effects of thermal annealing and decomposition processes on the structure are discussed in detail. The changes of Li content in materials were monitored by ICP spectrometry. It was established that the decomposition of the acetates at around 450 °C is a slurry-making process that compacts the powder. It was found that well lithiated samples with good life cycle and high capacity can be prepared using acetate precursors and a spray solution technique. The morphology, grain size and texturing can be controlled by the sintering time and temperature in combination with intermediate grinding. [Copyright &y& Elsevier]

Orthorhombic LiMnO2 was synthesized via the sol–gel process using citric acid as a chelating agent. The effect of varying the molar acid to metal ions ratio (R) on the structural and electrochemical properties of the synthesized compound was studied. Samples with high R (R=1,2) contain large amount of MnO impurity phase, which is electrochemically inactive and thus is detrimental to the electrochemical activity of the electrode. Therefore, the acid to metal ions ratio “R” should not be high. Samples with low R (R=0.5) exhibited a high initial capacity, above 190 mAh/g when cycled at a current density of 0.4 mA/cm2 at room temperature. The ac impedance results show that the initial capacity was improved (compared with ss-o-LiMnO2) due to the smaller particle size and good homogeneity, which improves the Li+ diffusion in the cathode. [Copyright &y& Elsevier]

Several multiple-ion-doped lithium nickel oxides with formula of LiMnxCoyNi1−x−yO2 were synthesized via solid-state reactions at high temperature. These phase-pure LiMnxCoyNi1−x−yO2 compounds have a layered hexagonal structure, and their electrochemical properties were systematically investigated. Typical cathodes can deliver a capacity in the range of 140–180 mAh/g with fairly stable cyclability. The kinetics of lithium insertion in these cathodes were characterized via ac impedance measurements. These newly developed compounds show great promises as cathode materials for future lithium-ion batteries with low cost and less toxicity. [Copyright &y& Elsevier]

The synthesis and electrochemical characteristics of LiCoxMnyNi1−x−yO2 as cathode materials for rechargeable lithium-ion batteries were investigated. The precursor CoxMnyNi1−x−y(OH)2 was obtained by the chemical co-precipitation method. LiCoxMnyNi1−x−yO2 (0≤x≤0.3, and y=0.2) was prepared by heating a mixture of CoxMnyNi1−x−y(OH)2 and Li2CO3 at 850–900 °C for 24 h in air. The X-ray diffraction (XRD) patterns indicated that pure phase LiCoxMnyNi1−x−yO2 was obtained. The scanning electron micrographs (SEMs) show that the synthesized LiCoxMnyNi1−x−yO2 compounds have good micro-morphology and uniform particle size. The electrochemical properties of these materials such as the galvanostatic charge–discharge performance and cyclic voltammetry were systematically measured. [Copyright &y& Elsevier]

Tin, tin oxide and NiSn-based nanocomposites with Al2O3 dispersion were prepared by ball milling to see their electrochemical properties as a new anode material for lithium-ion batteries. Electrochemical tests demonstrated that the initial charge–discharge capacities are very high for these materials. However, the capacity faded rapidly after the first cycle due to irreversible reactions. This is thought to be caused by the separation of the active materials from the inert oxide particles. The initial cycling efficiency was markedly improved by subsequent annealing of the ball-milled electrode. [Copyright &y& Elsevier]

Multiwall carbon nanotubes (MWNTs) were synthesized using chemical evaporation deposition (CVD). The morphology and microstructure of MWNTs were observed via HRTEM. The multiwall carbon nanotubes are entangled to bundles with a diameter of several tens of nanometers. Electrochemical properties of MWNTs were examined via a variety of electrochemical testing techniques. The MWNTs electrode demonstrated a reversible lithium storage capacity of 340 mAh/g with good cyclability at moderate current density. The kinetic properties of lithium insertion in MWNTs electrodes were characterized via ac impedance measurements. It was found that the lithium diffusion coefficient DLi decreases with an increase of Li-ion concentration in MWNTs electrodes. [Copyright &y& Elsevier]

Nano-SiC doping into MgB2 has induced extraordinary enhancement in critical current density (Jc) and flux pinning as a result of Si and C co-substitution into the lattice and the formation of nano-inclusions within the grains. In this work, a systematic study of the effect of the preparation parameters for processing MgB1.8(SiC)0.1/Fe tapes on critical temperature (Tc), critical current density (Jc) and microstructures was carried out. A mixture of Mg and B was doped with nano-SiC particle powder, and the SiC-doped samples were fabricated with the reaction in situ method. The samples were characterised using X-ray diffraction, scanning electronic microscopy and magnetisation measurements. It was found that the sintering temperature had a strong effect on both Tc and Jc. Tc was increased with sintering temperature, while Jc of the tapes sintered at 750 and 850 °C is higher than that of the tapes sintered at 680 and 950 °C. A longer sintering time was found to be beneficial to Tc but has negligible effects on Jc. Slow cooling improves the Jc field performance at 20 and 30 K. Uniaxial pressure (250 and 680 MPa) applied to tapes before sintering has almost no effect on Jc. [Copyright &y& Elsevier]

We have measured the imaginary susceptibility of MgB2 at different frequencies and at various dc applied magnetic fields up to 4 T. The method proposed firstly by Maley et al. on fixed applied magnetic field relaxation measurement was used to analyze the data. The information of the flux activation energy so extracted is found to be a nonlinear function of the current density, indicating a logarithmic relation U(H,J)=U0(H)ln(J0/J) of the current density in this material. The dependence of the activation energy on temperature is determined by a power law U(T)∝(1−(T/Tirr)2). The functional dependence U0(H)∝H−0.8 on the applied magnetic field is determined to be in the sample. [Copyright &y& Elsevier]

Polycrystalline MgB2 samples with 10 wt.% silicon powder addition were prepared by an in situ reaction process. Two different Si powders, one with coarse (44 μm) and the other with nano-size (<100 nm) particles were used for making samples. The phases, microstructures, and flux pinning were characterized by XRD, TEM, and magnetic measurements. It was observed that the samples doped with nano-sized Si powder showed a significantly improved field dependence of the critical current over a wide temperature range compared with both undoped samples and samples with coarse-Si added. Jc is as high as 3000 A/cm2 in 8 T at 5 K, one order of magnitude higher than for the undoped MgB2. X-ray diffraction results indicated that Si had reacted with Mg to form Mg2Si. Nano-particle inclusions and substitution, both observed by transmission electron microscopy, are proposed to be responsible for the enhancement of flux pinning in high fields. However, the samples made with the coarse-Si powders had a poorer pinning than the undoped MgB2. [Copyright &y& Elsevier]

The electrochemical performance of negative electrodes (anodes) made from mesocarbon microbeads (MCMB) in lithium-ion cells has been studied systematically via a variety of electrochemical techniques. The MCMB anodes have a stable lithium intercalation capacity of 325 mAh g−1 on high-rate charge–discharge cycling. Cyclic voltammetry shows only one reduction peak and one oxidation peak, which correspond to lithium-ion intercalation and de-intercalation, respectively. The diffusion of lithium ions in MCMB electrodes is characterized by ac impedance measurements. [Copyright &y& Elsevier]

A series of compounds LiMn0.7M0.3O2 (M=Ti, V, Zn, Mg, Mo, Co, Cr) with different doping elements were synthesized. It was found that the ionic size of the doping elements is not a discriminating factor in the structure of LiMn0.7M0.3O2 compounds. The LiMn0.7M0.3O2 (M=Cr, Zn, Mg, V) forms in the hexagonal structure, while the LiMn0.7M0.3O2 (M=Co, Ti, Mo) shows an orthorhombic structure. The LiMn0.7M0.3O2 compounds have less crystal distortion compared with o(orthorhombic)-LiMnO2. All substituted materials cycled between 4.4 and 2 V in Li cells show higher stability of capacity compared with the standard o-LiMnO2. AC impedance analysis results show that the charge transfer process and lithium ion diffusion process for doped LiMnO2 compounds are better than that for un-substituted compounds. [Copyright &y& Elsevier]

Orthorhombic LiMnO2 with small grain size was successfully synthesised using a one-step middle-temperature solid-state reaction (OSSS). Compared with the methods other researchers used, the OSSS method is much simpler. It is a one-step method without intermediate regrinding or other treatments. The o-LiMnO2 obtained showed a high initial capacity 180 mAh/g when cycled at a current density of 0.5 mA/cm2 at room temperature, and the rate capability was improved due to the smaller particle size. Therefore, the one-step middle temperature solid-state reaction could be a promising method for o-LiMnO2 compound synthesis. [Copyright &y& Elsevier]

The powder in tube method has been used to fabricate Ag- and Cu-clad MgB2 wires using an in situ reaction method. The effects of short time sintering on the critical current densities of Ag- and Cu-clad MgB2 wires were studied. All the samples were examined using X-ray diffraction, scanning electron microscope, and magnetization measurements. For Ag-clad wire Jc is improved by more than two times after the short time sintering process. Jc values of 1.2×105 A/cm2 in zero field and above 104 A/cm2 in 2 T at 20 K have been achieved for Ag-clad MgB2 wire which is only sintered for a few minutes at 800 °C. However, a remarkable degree of reaction has been found between the superconducting cores and the sheath materials, leading to the formation of Cu2Mg and Ag3Mg for Cu- and Ag-clad wires, respectively. The results show that the short sintering causes less reaction between the magnesium and the sheath materials and markedly improves the critical current density. Our result shows that iron is still the best sheath material because of the lack of reaction between Fe and the superconducting MgB2 material. [Copyright &y& Elsevier]

Cobalt oxides are investigated as anode materials for lithium-ion (Li-ion) batteries by means of a variety of electrochemical characterization techniques. The CoO electrode demonstrates a stable reversible lithium storage capacity of about 300 mAh g−1, even after 30 cycles. The reactivity of the cobalt oxides is attributed to the fact that the products of lithiation are in the form of nanosized products. [Copyright &y& Elsevier]

Cyclic voltammograms show that the reversibility of the manganese dioxide (MnO2) electrode is improved by means of using partially reduced samples. The crystal lattice of the intermediate is transformed by reduction. Formation of the manganous ion is very limited before the electrode potential reaches −0.4 V (versus Hg/HgO), thus the formation of Mn3O4 is prevented.The addition of Ni(OH)2 to partially reduced samples can further improve the reversibility of the MnO2 electrode, Ni(OH)2 delays the 2e− discharge step and decreases the opportunity for the co-existence of Mn(III) and Mn(II) ions and, thereby, prevents the formation of Mn3O4. The capacity retention of a cathode of partially reduced MnO2 (pr-MnO2) or pr-MnO2+Ni(OH)2 is much better than that of the MnO2 cathode. This demonstrates the feasibility of using pr-MnO2 as a cathode material. [Copyright &y& Elsevier]

Powder X-ray diffraction (XRD) is employed to identify the phase structure of Al-substituted nickel hydroxide, and its structural change after ageing treatment or charge/discharge cycles. The cell constants and the crystalline size of nickel hydroxides have been obtained by analysing the XRD pattern with Si as an internal standard. Results show that Al-substituted α-phase nickel hydroxide is very stable in strong alkaline medium even after 100 charge/discharge cycles. [Copyright &y& Elsevier]

Yb2CoMnO6 perovskite manganite was synthesised. Rietveld refinement of powder X-ray diffraction data indicated that this compound crystallised with a GdFeO3-type orthorhombic structure containing distorted (Co/Mn)O6 octahedra (Pnma; a=5.5593(2) A˚; b=7.4154(2) A˚; c=5.1825(1) A˚; V=213.65(1) A˚3; Z=2). The DC magnetisation and frequency dependence of real part of AC susceptibility was measured over a wide temperature range. A spin glass ground state at 40 K was observed to arise from a ferromagnetic state and caused by competition between the ferromagnetic and antiferromagnetic interaction. [Copyright &y& Elsevier]

Investigates the effect of the sinter-forging deformation rate on properties of Bi-2223 current leads. Fabrication of current leads by a combination of Cold Isostatic Pressing and sinter-forging methods; Measurements of contact resistance; Achievement of higher deformation rates.

Comparative studies on Bi-2212 single crystal, Bi-2212 tape and 2223 tape have been carried out using AC susceptibility, magnetisation and magnetoresistivity measurements. Bi-2212 crystals have been obtained through a spiral growth mechanism using KCl as flux. Magnetisation measurements show an enhanced flux pinning in the spiral grown crystals compared with crystals grown through a layer-by-layer mechanism. The fish tail effect in M-H loop is attributable to the spirals and screw dislocations in spiral grown Bi-2212 crystals. The irreversibility line for the 2223 tape is positioned at higher temperatures than that for the 2212 tape which is in turn positioned at higher temperatures than that for the 2212 crystals. The pinning potential, U/sub o/, for 2212 tape, determined by using resistance measurements in magnetic fields, is smaller than that of Ag/Bi-2223 tapes but larger than that for 2212 single crystals. These results indicate that the defects induced by mechanical deformation or spiral growth act as pinning centers in Bi-based materials, responsible for the improvement in flux pinning. [ABSTRACT FROM PUBLISHER]

MgB2 polycrystalline bulk samples with addition of 5 and 10 wt.% nano-sized Al2O3 powders were prepared by solid state reaction using pre-reacted MgB2. All the samples were sintered at 850 °C for 40 min in Ar. All the samples were characterized by X-ray diffraction, scanning electron microscopy and magnetic measurements. Results show that the critical current density and irreversibility fields decrease significantly with increasing Al2O3 level. Jc values decreased significantly by more than one order of magnitude. The Tc drops slightly from 37.9 to 36.6 K, but acquires a very wide transition width of more than 20 K. Furthermore, the amount of MgO was found to increase with increasing Al2O3 level, probably indicating that Mg was replaced by Al, with the excess Mg forming extra MgO. The field dependence of Jc for all the samples is also presented. [Copyright &y& Elsevier]

Hysteresis loop and magnetization relaxation measurements have been performed on a pure and a SiC-doped MgB2 samples. The normalized volume pinning forces determined from the hysteresis loop are observed to scale as a function of the reduced magnetic field (h=H/Hirr) with peaks at hmax≈0.2. This result implies that the dominating pinning mechanism in both materials is the pinning by normal surface defects. From magnetization relaxation measurements, the current dependence of the activation energy is found to be logarithmic. [Copyright &y& Elsevier]

Nanosize cobalt oxides (Co3O4) were synthesised by chemical decomposition of cobalt octacarbonyl in toluene at low temperature. Electrochemical properties of as-prepared Co3O4 as anodes in Li-ion cells were tested. The nanosized Co3O4 electrode demonstrate a stable reversible lithium storage capacity of 360 mAh/g within 30 cycles. The reactivity of as-prepared Co3O4 in Li-ion cells could be attributed to nanosize particles of Co3O4 and its lithiation products. [Copyright &y& Elsevier]

Background: Short-term exposure to ambient air pollution has been linked with daily hospitalization and mortality from acute coronary syndrome (ACS); however, the associations of subdaily (hourly) levels of criteria air pollutants with the onset of ACS and its subtypes have rarely been evaluated., Methods: We conducted a time-stratified case-crossover study among 1 292 880 patients with ACS from 2239 hospitals in 318 Chinese cities between January 1, 2015, and September 30, 2020. Hourly concentrations of fine particulate matter (PM 2.5 ), coarse particulate matter (PM 2.5-10 ), nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), carbon monoxide (CO), and ozone (O 3 ) were collected. Hourly onset data of ACS and its subtypes, including ST-segment-elevation myocardial infarction, non-ST-segment-elevation myocardial infarction, and unstable angina, were also obtained. Conditional logistic regressions combined with polynomial distributed lag models were applied., Results: Acute exposures to PM 2.5 , NO 2 , SO 2 , and CO were each associated with the onset of ACS and its subtypes. These associations were strongest in the concurrent hour of exposure and were attenuated thereafter, with the weakest effects observed after 15 to 29 hours. There were no apparent thresholds in the concentration-response curves. An interquartile range increase in concentrations of PM 2.5 (36.0 μg/m 3 ), NO 2 (29.0 µg/m 3 ), SO 2 (9.0 µg/m 3 ), and CO (0.6 mg/m 3 ) over the 0 to 24 hours before onset was significantly associated with 1.32%, 3.89%, 0.67%, and 1.55% higher risks of ACS onset, respectively. For a given pollutant, the associations were comparable in magnitude across different subtypes of ACS. NO 2 showed the strongest associations with all 3 subtypes, followed by PM 2.5 , CO, and SO 2 . Greater magnitude of associations was observed among patients older than 65 years and in the cold season. Null associations of exposure to either PM 2.5-10 or O 3 with ACS onset were observed., Conclusions: The results suggest that transient exposure to the air pollutants PM 2.5 , NO 2 , SO 2 , or CO, but not PM 2.5-10 or O 3 , may trigger the onset of ACS, even at concentrations below the World Health Organization air quality guidelines.