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21.
Lithium–sulfur batteries have great potential as next-generation energy-storage devices because of their high theoretical charge-storage capacity and the low cost of the sulfur cathode. To accelerate the development of lithium–sulfur technology, it is necessary to address the intrinsic material and extrinsic technological challenges brought about by the insulating active solid-state materials and the soluble active liquid-state materials. Herein, we report a systematic investigation of module-designed carbon-coated separators, where the carbon coating layer on the polypropylene membrane decreases the irreversible loss of dissolved polysulfides and increases the reaction kinetics of the high-loading sulfur cathode. Eight different conductive carbon coatings were considered to investigate how the materials’ characteristics contribute to the lithium–sulfur cell’s cathode performance. The cell with a nonporous-carbon-coated separator delivered an optimized peak capacity of 1112 mA∙h g−1 at a cycling rate of C/10 and retained a high reversible capacity of 710 mA∙h g−1 after 200 cycles under lean-electrolyte conditions. Moreover, we demonstrate the practical high specific capacity of the cathode and its commercial potential, achieving high sulfur loading and content of 4.0 mg cm−2 and 70 wt%, respectively, and attaining high areal and gravimetric capacities of 4.45 mA∙h cm−2 and 778 mA∙h g−1, respectively. 相似文献
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To determine the time-independent constitutive modeling for porous and multiphase nanocrystalline materials and understand the effects of grain size and porosity on their mechanical behavior, each phase was treated as a mixture of grain interior and grain boundary, and pores were taken as a single phase, then Budiansky's self-consistent method was used to calculate the Young's modulus of porous, possible multi-phase, nanocrystalline materials, the prediction being in good agreement with the results in the literature. Further, the established method is extended tosimulate the constitutive relations of porous and possible multi-phase nanocrystalline materials with small plastic deformation in conjunction with the secant-moduli approach and iso-strain assumption. Comparisons between the experimental grain size and porosity dependent mechanical data and the corresponding predictions using the established model show that it appears to be capable of describing the time-independent mechanical behaviors for porous and multi-phase nanocrystalline materials in a small plastic strain range. Further discussion on the modification factor, the advantages and limitations of the model developed were present. 相似文献
24.
以碱溶法制备的高孔隙度硅胶为基质,与γ-环氧丙基丙氧基三甲氧基硅烷配基进行共价键合,经过酸性水解,使其转化为二醇基,制成了高效亲水凝胶色谱填料。键合反应中采用70 ℃回流冷凝管,使生成的甲醇可顺利地排到体系外,促使反应向有利于键合的方向进行,以获得较高的配基密度。研究表明,水解反应条件与配基密度以及柱效密切相关。当配基密度为2.6~3.5 μmol/m2时,才能显示出较高的柱效。蛋白质分离实验结果显示,此填料的相对分子质量排阻极限为300000,牛血清白蛋白的回收率为99%。 相似文献
25.
P. Staszczuk D. Sternik G. W. Chądzyński E. Robens M. Błachnio 《Journal of Thermal Analysis and Calorimetry》2006,86(1):133-136
Nitrogen
adsorption measured at 77 K was used to characterize the surface heterogeneity
of high-temperature superconductor surfaces. Properties relating to adsorption
and porosity of the solids (adsorption capacity, specific surface area, radii
and volume of the pores, pore-size distribution function) were determined
from nitrogen adsorption–desorption isotherms and atomic force microscopy
(AFM) for a series of oxide superconductors. It is shown that the adsorption
isotherms of all samples are S-shaped and belong to type II according to the
IUPAC classification. On the basis of the nitrogen adsorption isotherms and
AFM data, fractal dimensions were determined and correlations found with adsorption
and porosity parameters. 相似文献
26.
Ivana Brekalo David E. Deliz Leonard J. Barbour Michael D. Ward Tomislav Fri
i K. Travis Holman 《Angewandte Chemie (International ed. in English)》2020,59(5):1997-2002
Guanidinium organosulfonates (GSs) are a large and well‐explored archetypal family of hydrogen‐bonded organic host frameworks that have, over the past 25 years, been regarded as nonporous. Reported here is the only example to date of a conventionally microporous GS host phase, namely guanidinium 1,4‐benzenedisulfonate ( p ‐G2BDS ). p ‐G2BDS is obtained from its acetone solvate, AcMe@ G2BDS , by single‐crystal‐to‐single‐crystal (SC‐SC) desolvation, and exhibits a Type I low‐temperature/pressure N2 sorption isotherm (SABET=408.7(2) m2 g?1, 77 K). SC‐SC sorption of N2, CO2, Xe, and AcMe by p ‐G2BDS is explored under various conditions and X‐ray diffraction provides a measurement of the high‐pressure, room temperature Xe and CO2 sorption isotherms. Though p ‐G2BDS is formally metastable relative to the “collapsed”, nonporous polymorph, np ‐G2BDS , a sample of p ‐G2BDS survived for almost two decades under ambient conditions. np ‐G2BDS reverts to zCO2@ p ‐G2BDS or yXe@ p ‐G2BDS (y,z=variable) when pressure of CO2 or Xe, respectively, is applied. 相似文献
27.
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29.
Juan A. Allegretto Agustín Iborra Dr. Juan M. Giussi Dr. Catalina von Bilderling Dr. Marcelo Ceolín Dr. Sergio Moya Dr. Omar Azzaroni Dr. Matias Rafti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(54):12388-12396
This work reports on a novel and versatile approach to control the structure of metal–organic framework (MOFs) films by using polymeric brushes as 3D primers, suitable for triggering heterogeneous MOF nucleation. As a proof-of-concept, this work explores the use of poly(1-vinylimidazole) brushes primer obtained via surface-initiated atom transfer radical polymerization (SI-ATRP) for the synthesis of Zn-based ZIF-8 MOF films. By modifying the grafting density of the brushes, smooth porous films were obtained featuring inherently hydrophobic microporosity arising from ZIF-8 structure, and an additional constructional interparticle mesoporosity, which can be employed for differential adsorption of targeted adsorbates. It was found that the grafting density modulates the constructional porosity of the films obtained; higher grafting densities result in more compact structures, while lower grafting density generates increasingly inhomogeneous films with a higher proportion of interparticle constructional porosity. 相似文献
30.
Optical emission resulting from sputtered species during ion bombardment of porous and oxidized porous silicon targets has been studied. Samples were bombarded with 5‐keV Kr+ ions at an incidence angle of 70 degrees, and the light emitted was analyzed over the wavelength range 200–300 nm. The surface morphology was investigated, and the micrographs revealed grooves parallel to the plane of incidence when the porosity was surprisingly observed in the grooves under each pore. The results are discussed as a function of the incidence angle and the porosity of the silicon targets. 相似文献