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1.
The structure and characteristic of carbon materials have a direct influence on the electrochemical performance of sulfur-carbon composite electrode materials for lithium-sulfur battery.In this paper,sulfur composite has been synthesized by heating a mixture of elemental sulfur and activated carbon,which is characterized as high specific surface area and microporous structure.The composite,contained 70%sulfur,as cathode in a lithium cell based on organic liquid electrolyte was tested at room temperature....  相似文献   

2.
Nanocrystalline ZnMn2O4 is prepared by a polymer-pyrolysis route and used as a novel anode for lithium ion batteries. XRD and HRTEM studies reveal that the products are highly phase-pure and 30–60 nm in size. Galvanostatic cycling of ZnMn2O4 electrode at 100 mA g−1 (about 0.52 mA cm−2) between 0.01 and 3.0 V up to 50 cycles exhibits almost stable cycling performance between 10 and 50 cycles with only an average capacity fade of 0.20% per cycle and the electrode still maintains a capacity of 569 mAh g−1 after 50 cycles.  相似文献   

3.
Commercial LiCoO2 has been modified with MnSiO4 as a novel coating material. The structures, morphologies, overcharge behaviors and thermal stabilities of the pristine and MnSiO4-coated LiCoO2 materials were studied. The MnSiO4-coated LiCoO2 had initial discharge specific capacities of 181.1 and 232.2 mAh g−1 within the potential ranges 2.75–4.5 and 2.75–4.7 V (vs. Li+/Li), respectively. It was found that the overcharge tolerance of the coated cathode was significantly better than that of the pristine LiCoO2 under the same conditions – the discharge specific capacities of the coated cathode at upper charge cutoff voltages of 4.5 and 4.7 V were as high as 168.7 and 154.3 mAh g−1, respectively, after 50 cycles. Moreover, DSC showed that the coated LiCoO2 had a higher thermal stability than the pristine LiCoO2.  相似文献   

4.
Cathodic electrophoretic deposition (EPD) method has been developed for the deposition of manganese dioxide films. It was shown that phosphate ester (PE) is an effective charging additive, which provides stabilization of manganese dioxide nanoparticles in suspensions. The influence of PE concentration and deposition voltage on the deposition efficiency has been studied. EPD has been utilized for the fabrication of porous nanostructured films with thickness in the range of 0.5–20 μm for application in electrochemical supercapacitors (ES). Cyclic voltammetry and chronopotentiometry data for the films tested in the 0.1 M Na2SO4 solutions showed capacitive behavior in the voltage window of 1 V. The highest specific capacitance (SC) of 377 F g−1 was obtained at a scan rate of 2 mV s−1. The SC decreased with increasing film thickness and increasing scan rate in the range of 2–100 mV s−1. The deposition mechanism, kinetics of deposition and charge storage properties of the films are discussed.  相似文献   

5.
Zn2SnO4@PANI composites were synthesized via a micro emulsion polymerization method. The outer surfaces of monodispersed cubes are covered with amorphous aggregated PANI. The addition of PANI can create a buffering structure for Zn2SnO4 cubes. Compared with Zn2SnO4 cubes, Zn2SnO4@PANI composites show an improved electrochemical performance (491.0 mAh g?1 at a current density of 600 mAg?1 after 50 cycles). It is believed that PANI coating is a simple and effective way to improve the cycling performance for lithium batteries.  相似文献   

6.
Hierarchically ordered porous nickel oxide array film was prepared by electrodeposition through monolayer polystyrene spheres template. The as-prepared film had a highly porous structure of interconnected macrobowls array possessing nanopores. As anode material for lithium ion batteries, the porous array NiO film exhibited weaker polarization, higher coulombic efficiency and better cycling performance in comparison with the dense NiO film. After 50 cycles, the discharge capacity of porous array NiO film was 518 mAh g? 1 at 1 C rate, higher than that of the dense NiO film (287 mAh g? 1). The enhancement of the electrochemical properties was due to the unique hierarchical porous architecture, which provided fast ion/electron transfer and alleviated the structure degradation during the cycling process.  相似文献   

7.
Silicon monoxide/graphite/multi-walled carbon nanotubes (SiO/G/CNTs) material was prepared by ball milling followed by chemical vapor deposition method and characterized by X-ray diffraction, scanning electron microscopy (SEM), galvanostatic charge–discharge, and AC impedance spectroscopy, respectively. The results revealed that SiO/G/CNTs exhibited an initial specific discharge capacity of 790 mAh g−1 with a columbic efficiency of 65%. After 100 cycles, a high reversible capacity of 495 mAh g−1 is still retained. The improved electrochemical properties were due to beneficial SEI by the SEM and EIS results.  相似文献   

8.
A new type of polyphenylene, ionic liquid (IL) 1,3-methylimidazolium hexafluorophosphate substituted, has been prepared by electrodeposition on Au electrode surface via pulse galvanostatic method in 1-butyl-3-methylimidazolium hexafluorophosphate solution. The obtained polymer film had a spherulitic morphology with smallest grains of around 500 nm. Infrared spectrometry revealed that polyphenylene was deposited to a certain extent. The capacitive behavior of the IL substituted polyphenylene was investigated by cyclic voltammetry (CV) and galvanostatic charge–discharge method in 0.2 mol L−1 H2SO4 aqueous solutions or pure IL [bmim]PF6. The specific capacitance of the polymer at the charge–discharge current density of 1 mA cm−2 equaled 206 F g−1 in acidic aqueous solution or 164 F g−1 in [bmim]PF6. Additionally, excellent charge–discharge cycle stability (over 85% value of specific capacitance remained after 600 charge–discharge cycles) and power characteristics of the polymer electrode were observed in both electrolytes.  相似文献   

9.
In this work, headspace solid-phase micro-extraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) method for analysis of butyltin compounds in sediment samples was upgraded by the introduction of tandem mass spectrometry (MS/MS). Optimization and validation of this method based on an one step procedure, tetraethylborate in situ ethylation with simultaneous extraction by headspace SPME, combined with tandem mass spectrometry is described. A simple leaching/extraction step of mono-(M), di-(D) and tri-(T) butyltin (BT) compounds from the sediment is required as sample pre-treatment. The combination of the two techniques headspace SPME and MS/MS, led to very little matrix interference which permitted to attain limits of detection three or more orders of magnitude lower than those attained in previous methods: 0.3 pg g− 1 for MBT, 1 pg g− 1 for DBT and 0.4 pg g− 1 for TBT. Linear response range was from 0.02–1260 ng g− 1 for MBT, 0.07–1568 ng g− 1 for DBT and 0.04–2146 ng g− 1 for TBT and RSD < 15% was also obtained. The method was efficiently applied to a real sample sediment from Sado River estuary in Portugal, revealing the existence of BTs pollution, as the TBT level of 189 ± 15 ng g− 1 was much higher than the maximum established as provisional ecotoxicological assessment criteria.  相似文献   

10.
We reported sulfonated poly(ether ether ketone) (SPEEK, 61% degree of sulfonation)–metal oxides (MO2:SiO2, TiO2 and ZrO2)–polyaniline composite membranes. Metal oxides were incorporated into the swelled SPEEK membrane by sol–gel method and cured by thermal treatment. SPEEK–metal oxide membranes surfaces were modified with polyaniline (PANI) by a redox polymerization process. It was observed that water retention capacity of membrane was increased and methanol permeability was reduced due to synergetic effect of metal oxides and surface modification with polyaniline. These composite membranes showed extremely low methanol permeability (1.9–1.3 × 10−7 cm2 s−1), which was lower than till reported values either for SPEEK–metal oxide or SPEEK/PANI membranes. Relatively high selectivity parameter (SP) values at 343 K of these membranes, especially S–SiO2–PANI and S–TiO2–PANI, indicated their great advantages over Nafion117 (N117) membrane for targeting on moderate temperature applications due to the synergetic effect of MO2 and PANI in SPEEK matrix. S–TiO2–PANI and N117 showed comparable cell performance in direct methanol fuel cell (DMFC).  相似文献   

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