摘要：
Polyvinyl pyrrolidone (PVP) as dispersant was employed to assist the hydrothermal synthesis of MoS2. The results show that the interlayer distance of the as-obtained MoS2 is smaller compared with the original MoS2 without PVP-assistance using XRD, SEM and TEM techniques for characterization. Investigations of the electrochemical performances of MoS2 with different interlayer distance as anode material for LIBs demonstrate that the specific capacity and the cycling performance of lithium storage of MoS2 is significantly dependent on the interlayer distance of MoS2, furthermore causing the different mechanism of lithium storage. This might be attributed to the varied internal resistance and Li-ion diffusion in layered MoS2 due to the different interlayer distance, which is validated from electrochemical impedance spectroscope of MoS2 electrode.
摘要：
The hierarchical nanostructured FeS2 hollow microspheres composed of nanoflakes were fabricated based on Ostwald ripening using sulfur powder as sulfur source and triethanolamine as both solvent and reducing agent, and electrochemically investigated as cathode material for lithium-ion batteries. The as-obtained FeS2 electrode delivered an initial capacity of 886.3 mA h g−1 at 0.1 C at ambient temperature, which is one of the highest values in the reported results. In the subsequent cycles following the first cycle, the electrode exhibited good reversibility at ambient temperature, resulting in good cycling stability and performance, and the discharge capacity of 392.7 mA h g−1 at 1 C was still retained after 30 cycles. This might be attributed to the unique FeS2 structure with hierarchical nanostructured hollow microspheres, showing potential to develop FeS2 cathode materials with high energy density for lithium-ion batteries.
关键词：
alpha-LiFeO2;Electrochemical performance;Lithium-ion batteries;Solid state method
摘要：
In this work, nanosized alpha-LiFeO2 were synthesized by a simple low-temperature solid state method. The obtained alpha-LiFeO2 nanoparticles were investigated by the measurements of X-ray diffraction pattern, scanning electronic microscopy, transmission electron microscope and electrochemical performance. Electrochemical measurements showed that the initial discharge capacity was 277.9, 188.4, and 158.2 mAh g(-1) at 0.1 C, 1 C, and 2 C, respectively. Meanwhile, the alpha-LiFeO2 nanoparticles exhibited improved cycle stability (123 mAh g(-1) at 2 C after 60 cycles). The high capacity, improved rate performance and cycle stability can be attributed to the smaller particle sizes, which can facilitate the contact between active materials and the electrolyte, enhance lithium and electron transport during cycling.
摘要：
Ball-in-ball CuSCN hollow architecture is successfully synthesized by a facile one-pot aqueous solution method in the presence of poly(vinylpyrrolidone) at room temperature. The as-synthesized products are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance absorption spectra (DRS) and nitrogen adsorption–desorption measurement. A possible formation mechanism for CuSCN hollow spheres by the difference of solubility products (Ksp) of CuBr and CuSCN or chemical self-transformation is proposed based on the experimental observations. The band gap energy of hollow CuSCN sphere is estimated to be 3.77 eV based on the results of optical measurement. The BET specific surface area of ball-in-ball CuSCN hollow architecture is calculated to be 30.5 m2/g and it has a bimodal mesoporous structure from nitrogen adsorption–desorption investigation.
关键词：
CuS cathode;Electrochemical properties;Lithium ion battery;Cyclic voltammetry
摘要：
A simple approach, for the first time, was presented for in situ preparation of the CuS cathode. The obtained CuS cathodes were investigated by the measurements of X-ray diffraction pattern, scanning electronic microscopy, and electrochemical performance. The results indicate the CuS cathodes are composed of plenty of nano flakes, which construct a large 3-D net structure. Moreover, the CuS cathodes exhibit reversible capacity of 447.4, 414.1, 389.9 and 376.0 mAh g−1 at 0.2 C, 0.5 C, 1 C and 2 C respectively and excellent cycle stability for more than 100 cycles. The possible mechanism of the unique stability of the CuS cathode was discussed.
摘要：
A chicken eggshell membrane (ESM) was used as a solid-phase extraction adsorbent for the separation and preconcentration in combination with inductively coupled plasma-mass spectrometry (ICP-MS) for the determination of trace gold in geological samples. Gold (Au) was quantitatively separated and preconcentratcd in 1.2 mol L~(-1) HC1 at a sample flow rate of 2.0 mL min.~1 using the ESM microcolumn system. The gold adsorbed on the microcolumn was effectively eluted with a mixture of 1% thiourea and 0.12 mol L1 HCL The effects of acid concentration, sample flow rate and volume, eluent conditions and interfering ions were carefully investigated. The transition- and heavy-metal ions did not interfere with either the separation/preconcentration or the determination. The limit of detection of the method for Au was 0.92 ng L~(-1). The method was validated using certified reference materials and applied to the determination of trace Au in geological samples with satisfactory results.
关键词：
Lithium Manganese Phosphates;Doping;Zinc;Lithium Ion Battery;Electrochemistry
摘要：
Olivine structure LiMnPO/C as cathode materials for Li-ion batteries were synthesized via a simple solid-state reaction. Improvement of the electrochemical performance of LiMnPO_4/C cathode material was realized significantly by the method of doping Zn. The obtained LiMn_0.95Zn_0.05PC_4/C electrode material was studied by the measurements of X-ray diffraction pattern, scanning electronic microscopy, electrochemical impedance spectroscopy and electrochemical performance. The results indicate that the LiMn_0.95Zn_0.05PC_4/C materials exhibit discharge specific capacity of 140.2 mA h g~-1 at 0.02 C rate and better rate capability. These excellent results are elucidated by E1S test, which showed that there was the decrease of charge transfer resistance and faster lithium-ion diffusion in LiMnPO_4/C cathode materials after Zn doping.
