In isochronous mass spectrometry (IMS) established in heavy-ion storage rings the revolution times of the stored secondary ions should be independent of their velocity spread. However, this ...isochronous condition is fulfilled only in first order and in a small range of revolution times. To correct for the non-isochronicity an additional measure of the velocity or magnetic rigidity of each stored ion is required. For this purpose two new time-of-flight (TOF) detectors were installed in a straight section of the experimental Cooler Storage Ring CSRe in Lanzhou. The performance of the new time-of-flight (TOF) detectors, which is crucial for the achievable efficiencies and mass resolving power, was significantly improved. The time resolution of the TOF detector in offline tests was σ=18.5±2ps. The detector setup was put into operation with a stable beam of 78Kr.
Pure Ni and three Ni–Co alloys films, i.e. Ni–4wt.%Co, Ni–18wt.%Co, and Ni–40wt.%Co, are electrodeposited at room temperature from the choline chloride/ethylene glycol deep eutectic solvent dissolved ...by nickel or/and cobalt chlorides. Electrodeposition mechanism, microstructure, and corrosion properties of the films are investigated. Surface morphology and chemical composite of the films are significantly dependent on the Ni2+ and Co2+ concentrations in the electrolytes. Interestingly, it is found that the amount of cobalt in the Ni–Co alloy films is significantly lower than that present in the electrolytes, which indicates an absence of anomalous codeposition process for the non-aqueous electrolytes. However, anomalous codeposition of Ni–Co deposits is frequently observed for the aqueous electrolytes. The Ni–Co alloy films possess face-centered cubic structures and refined grains revealed by X-ray diffractometer and scanning electron microscope. Potentiodynamic polarization measurements show that the Ni film exhibits the noblest corrosion potential and the lowest corrosion current compared with the Ni–Co alloys films. Moreover, the more Co content the Ni–Co films have, the more negative corrosion potential and the higher corrosion current the films exhibit.
► Electrodeposition of Ni–Co films from a deep eutectics system. ► Co2+ concentrations influence surface morphology and chemical composite of films. ► Ni–Co deposition with a non-anomalous codeposition process.
Isochronous mass spectrometry (IMS) in storage rings is a powerful tool for mass measurements of exotic nuclei with very short half-lives down to several tens of microseconds, using a multicomponent ...secondary beam separated in-flight without cooling. However, the inevitable momentum spread of secondary ions limits the precision of nuclear masses determined by using IMS. Therefore, the momentum measurement in addition to the revolution period of stored ions is crucial to reduce the influence of the momentum spread on the standard deviation of the revolution period, which would lead to a much improved mass resolving power of IMS. One of the proposals to upgrade IMS is that the velocity of secondary ions could be directly measured by using two time-of-flight (double TOF) detectors installed in a straight section of a storage ring. In this paper, we outline the principle of IMS with double TOF detectors and the method to correct the momentum spread of stored ions.
•Sm2O3 is well coated on LiLi0.2Mn0.56Ni0.16Co0.08O2 by simple wet chemical method.•The coated sample exhibits high capacity of 234.5mAhg−1 at 1C.•Capacity retention of 91.5% is obtained at 1C ...(200mAg−1) after 80 cycles 25°C.•EIS shows the thin Sm2O3 layer mainly reduces the charge transfer resistance.
Sm2O3-modified LiLi0.2Mn0.56Ni0.16Co0.08O2 was synthesized via a simple wet chemical process followed by a solid state reaction. A thin Sm2O3 layer with a thickness of about 2.5nm was uniformly coated on the surface of the Li-rich layered oxide particles. After Sm2O3 surface modification, high discharge capacity of 214.6mAhg−1 with a retention of 91.5% is obtained at a current density of 200mAg−1 between 2.0V and 4.8V after 80 cycles. Electrochemical impedance spectroscopy (EIS) shows that the thin Sm2O3 layer mainly reduces the charge transfer resistance and stabilizes the surface structure of the active material during cycling. Sm2O3 modification will be a promising approach to improve the cyclic stability of Li-rich layered oxides.
LiVO3 is synthesized via a ball-milling route followed by a solid-state reaction at different temperatures. As cathode materials for lithium ion batteries, the electrochemical performances of LiVO3 ...are investigated by galvanostatic charge–discharge test and electrochemical impedance spectroscopy (EIS). The LiVO3 compound synthesized at 350 °C possesses the optimal performance, delivering an initial discharge capacity of 302.5 mAh g−1 between 1.0 V and 3.5 V at a current density of 50 mA g−1, and exhibiting a good cycling stability. Li-ion diffusion coefficient of 10−9.5–10−8 cm2 s−1 in the LiVO3 electrode is calculated by galvanostatic intermittent titration technique (GITT). The good performances can be attributed to its relatively low crystallization and small particle size.
► LiVO3 is synthesized by a ball-milling route followed by a solid-state reaction. ► The LiVO3 compound synthesized at 350 °C possesses the optimal performance. ► It delivers an initial discharge capacity of 302.5 mAh g−1. ► Li-ion diffusion coefficient of 10−9.5–10−8 cm2 s−1 is calculated by GITT.
► Carbon is coated on Li1.048Mn0.381Ni0.286Co0.286O2 by a direct current magnetron sputtering. ► Cycle capability and rate performance are improved after carbon coating. ► A specific capacity of ...145mAhg−1 can be obtained at 5C (1500mAg−1). ► The coated layer restrains the reaction between the electrolyte and the electrode.
Carbon-coated layered oxide Li1.048Mn0.381Ni0.286Co0.286O2 is prepared by combining a co-precipitation and a direct current magnetron sputtering. TEM images show that the carbon layer is relatively well coated on the surface of oxide particles. The Li1.048Mn0.381Ni0.286Co0.286O2/C composite delivers an initial discharge capacity of 203.2mAhg−1 between 2.5 and 4.5V at 0.1C, and 94% of the initial discharge capacity can be retained after 100 cycles. Moreover, the carbon-coated oxide exhibits noticeable high-rate capacity of 145mAhg−1 at 5C, much higher than the pristine one (103mAhg−1 at 5C). The improved discharge capacity and cycle performance are attributed to the carbon coating, which protects the Li-rich cathode material from reacting with the electrolyte and retarding the incrassation of SEI film on the surface of oxide particles.
•Bias-graded Ti-contained a-C composite film was deposited by magnetron sputtering.•The film has the hardness of 19GPa with high toughness and adhesion strength.•The bias-graded film showed excellent ...tribological property in ambient air.•Its good wear resistance in Hanks’ solution contributes to biological applications.
Ti-contained a-C gradient composite film with a thickness 1.5μm was deposited on medical Ti6Al4V alloy substrate using a closed field unbalanced magnetron sputtering with bias-graded voltage through −20V to −150V. The mechanical and tribological properties were evaluated from nanoindentation, scratch test and ball-on-disk tribometer. Compared with the constant-bias film deposited at −150V, the bias-graded film has the approximate hardness (19GPa) but high toughness and adhesion strength. At a normal load of 10N, the bias-graded composite film shows a low friction coefficient of 0.08 and wear rate of 2.89×10−16m3N−1m−1 in ambient air. While in Hanks’ solution, the film has the same low friction coefficient but low wear rate of 4.63×10−17m3N−1m−1. Excellent wear resistance in Hanks’ solution may bring about a biological application for the Ti-contained a-C gradient composite film.
TiO2@WO3 core/shell nanorod arrays are prepared by the combination of hydrothermal and electrodeposition method. The array films show remarkable enhancement of the electrochromic properties. In ...particular, a significant optical modulation (57.2% at 750nm, 70.3% at 1800nm and 38.4% at 10μm), fast switching speed (2.4s and 1.6s), high coloration efficiency (67.5cm2C−1 at 750nm) and excellent cycling performance (65.1% after 10,000 cycles) are achieved for the core/shell nanorod arrays. The improved electrochromic properties are mainly attributed to the core/shell structure and the porous space among the nanorod array, which makes the ion diffusion become easier and it also gives larger surface area for charge-transfer reactions. The data present great promise for the TiO2@WO3 core/shell nanorod arrays as practical electrochromic materials.
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•TiO2@WO3 core/shell nanorod arrays are successfully prepared.•The arrays exhibit larger optical modulation, fast switching speed and high CE.•Excellent cycling performance are achieved for the core/shell nanorod arrays.
Hierarchical, nanostructured copper oxide spheres were synthesized in a stirred solution of cupric acetate and ammonium hydroxide. Cetyltrimethylammonium bromide (CTAB) was used as a surfactant to ...modify the surface morphology of CuO spheres. Ordered nano-needle arrays can be formed on the surface of the CuO spheres (instead of disordered nano-leaves) in the presence of CTAB. Each CuO sphere is about 2
μm in diameter and possesses a large number of nano-needles that are about 20–40
nm in width and more than 300
nm in length. The needle-like hierarchical structure can greatly increase the contact area between CuO and electrolyte, which provides more sites for Li
+ accommodation, shortens the diffusion length of Li
+ and enhances the reactivity of electrode reaction, especially at high rates. After 50 cycles, the reversible capacity of the prepared needle-like CuO can sustain 62.4% and 56.4% of the 2nd cycle at a rate of 0.1
C and 1
C, respectively.
The Li3V2(PO4)3/C cathode materials are synthesized by a simple solid-state reaction process using stearic acid as both reduction agent and carbon source. Scanning electron microscopy and ...transmission electron microscopy observations show that the Li3V2(PO4)3/C composite synthesized at 700°C has uniform particle size distribution and fine carbon coating. The Li3V2(PO4)3/C shows a high initial discharge capacity of 130.6 and 124.4mAhg−1 between 3.0 and 4.3V, and 185.9 and 140.9mAhg−1 between 3.0 and 4.8V at 0.1 and 5C, respectively. Even at a charge–discharge rate of 15C, the Li3V2(PO4)3/C still can deliver a discharge capacity of 103.3 and 112.1mAhg−1 in the potential region of 3.0–4.3V and 3.0–4.8V, respectively. Based on the analysis of cyclic voltammograms and electrochemical impedance spectra, the apparent diffusion coefficients of Li ions in the composites are in the region of 1.09×10−9 and 4.95×10−8cm2s−1.
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