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971.
972.
Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances.Herein,a new type of flexible Na_3(VOPO_4)_2F cathode with nanocubes tightly assembled on carbon cloth is fabricated by a facile solvothe rmal method for the first time.The cathode is able to exhibit superior rate capability and stable cycling performa nce up to 1000 cycles,due to the surface-assembling of crystalline nanocubes on carbon fibers.In addition,it shows good mechanical flexibility,nearly no capacity decay is observed after continuous bending of 500 times.With this novel cathode and a directly-grown Na_2Ti_2O_5 anode,a fully binde r-free Na-ion battery is assembled.It can deliver a high wo rking voltage and increased gravimetric energy/power densities(maximum values:220.2 Wh/kg;5674,7 W/kg),and can power a LED indicator at bending angles fro m 0° to 180°. 相似文献
973.
Yuanyuan Yu Huihui Gao Jiadeng Zhu Dazhe Li Fengxia Wang Chunhui Jiang Tianhaoyue Zhong Shuheng Liang Mengjin Jiang 《中国化学快报》2021,32(1):203-209
Low-cost silicon microparticles(SiMP),as a substitute for nanostructured silicon,easily suffer from cracks and fractured during the electrochemical cycle.A novel n-type conductive polymer binder with excellent electronic and ionic conductivities as well as good adhesion,has been successfully designed and applied for high-performance SiMP anodes in lithium-ion batteries to address this problem.Its unique features are attributed to the stro ng electron-withdrawing oxadiazole ring structure with sulfonate polar groups.The combination of rigid and flexible components in the polymer ensures its good mechanical strength and ductility,which is beneficial to suppress the expansion and contraction of SiMP s during the charge/discharge process.By fine-tuning the monomer ratio,the conjugation and sulfonation degrees of the polymer can be precisely controlled to regulate its ionic and electronic conductivities,which has been systematically analyzed with the help of an electrochemical test method,filling in the gap on the conductivity measurement of the polymer in the doping state.The experimental results indicate that the cell with the developed n-type polymer binder and SiMP(~0.5 μm) anodes achieves much better cycling performance than traditional non-conductive binders.It has been considered that the initial capacity of the SiMP anode is controlled by the synergetic effect of ionic and electronic conductivity of the binder,and the capacity retention mainly depends on its electronic conductivity when the ionic conductivity is sufficient.It is worth noting that the fundamental research of this wo rk is also applicable to other battery systems using conductive polymers in order to achieve high energy density,broadening their practical applications. 相似文献
974.
975.
Yang M Wang W Yuan F Zhang X Li J Liang F He B Minch B Wegner G 《Journal of the American Chemical Society》2005,127(43):15107-15111
The synthesis of a block codendrimer (g3-PBE-b-g3-PMDC), composed of a third-generation poly(benzyl ether) (PBE) monodendron and an aliphatic polyether (PMDC) monodendron is reported. In THF/diiospropyl ether (1:1) the PMDC block functions as a "hydrophilic" block, while the PBE acts as a "hydrophobic" block. The codendrimer can form interdigitated layers leading to vesicle formation. Tapping mode atomic force microscopy (AFM), dynamic light scattering (DLS), and transmission electron microscopy (TEM) were used to characterize the vesicles. The effect of molecular architecture on the formation of the interdigitated layers and vesicles was studied. 相似文献
976.
[Chemical reaction: see text] Polysubstituted furans and highly functionalized 2H-pyrans were prepared in good yields by DABCO-catalyzed reactions of alpha-halo carbonyl compounds with dimethyl acetylenedicarboxylate (DMAD) at room temperature. 相似文献
977.
A new method for the determination of trace cadmium in water samples by flame atomic absorption spectrometry (FAAS) after
cloud point extraction (CPE) is proposed. The method is based on the complexation of Cd with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone
(PMBP) in the presence of non-ionic micelles of Triton X-100. The effect of experimental conditions such as pH, concentration
of chelating agent and surfactant, equilibration temperature and time on cloud point extraction was studied. Under the optimum
conditions, the detection limits are 0.64 ng mL±1 with relative standard deviations (RSDs) of 2.1% (n = 10). The proposed method was applied to the determination of trace
cadmium in water samples with satisfactory results. 相似文献
978.
Experimental and modeling study on decomposition kinetics of methane hydrates in different media 总被引:6,自引:0,他引:6
Liang M Chen G Sun C Yan L Liu J Ma Q 《The journal of physical chemistry. B》2005,109(40):19034-19041
The decomposition kinetic behaviors of methane hydrates formed in 5 cm3 porous wet activated carbon were studied experimentally in a closed system in the temperature range of 275.8-264.4 K. The decomposition rates of methane hydrates formed from 5 cm3 of pure free water and an aqueous solution of 650 g x m(-3) sodium dodecyl sulfate (SDS) were also measured for comparison. The decomposition rates of methane hydrates in seven different cases were compared. The results showed that the methane hydrates dissociate more rapidly in porous activated carbon than in free systems. A mathematical model was developed for describing the decomposition kinetic behavior of methane hydrates below ice point based on an ice-shielding mechanism in which a porous ice layer was assumed to be formed during the decomposition of hydrate, and the diffusion of methane molecules through it was assumed to be one of the control steps. The parameters of the model were determined by correlating the decomposition rate data, and the activation energies were further determined with respect to three different media. The model was found to well describe the decomposition kinetic behavior of methane hydrate in different media. 相似文献
979.
A novel diterpene derivative, 5-methyl-5-(4,8,12-trimethyl-tridecyl)-dihydro-furan-2-one (1) and a new chromone, 5-hydroxy-7-methoxy-3-methyl-chromen-4-one (2), along with a known compound, phytol (3) have been isolated from the aerial parts of Hypericum perforatum. Their structures were established on the basis of spectroscopic analysis and by comparison with published values. 相似文献
980.
Chen P Nie S Mi W Wang XC Liang SP 《Rapid communications in mass spectrometry : RCM》2004,18(2):191-198
A simple method of solid-phase derivatization and sequencing of tryptic peptides has been developed for rapid and unambiguous identification of spots on two-dimensional gels using post-source decay (PSD) matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The proteolytic digests of proteins are chemically modified by 4-sulfophenyl isothiocyanate. The derivatization reaction introduces a negative sulfonic acid group at the N-terminus of a peptide, which can increase the efficiency of PSD fragmentation and enable the selective detection of only a single series of fragment ions (y-ions). This chemically assisted method avoids the limitation of high background normally observed in MALDI-PSD spectra, and makes the spectra easier to interpret and facilitates de novo sequencing of internal fragment. The modification reaction is conducted in C(18) microZipTips to decrease the background and to enhance the signal/noise. Derivatization procedures were optimized for MALDI-PSD to increase the structural information and to obtain a complete peptide sequence even in critical cases. The MALDI-PSD mass spectra of two model peptides and their sulfonated derivatives are compared. For some proteins unambiguous identification could be achieved by MALDI-PSD sequencing of derivatized peptides obtained from in-gel digests of phosphorylase B and proteins of hepatic satellite cells (HSC). 相似文献