The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
Chunrong Wan - One of the best experts on this subject based on the ideXlab platform.
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Ytterbium coating of spherical Ni(OH)2 cathode materials for Ni–MH batteries at elevated temperature
Journal of Power Sources, 2006Co-Authors: Li Wang, Changyin Jiang, Chunrong WanAbstract:Abstract The Yb/Co coated nickel Hydroxides were prepared by precipitation of Yb(OH) 3 on the surface of spherical nickel hydroxide, followed by precipitation of Co(OH) 2 on its surface. The optimum coating content of ytterbium was around 2% (atomic concentration) to obtain high discharge capacity at 60 °C. It was shown that the discharge capacity of nickel hydroxide at high temperatures was improved by coating of ytterbium and cobalt hydroxide. The high temperature performances of the sealed AAA-sized Ni–MH batteries using Yb/Co coated nickel hydroxide as positive electrodes were carried out, showing much better than those using the un-coated and only Co(OH) 2 coated nickel hydroxide electrodes. The charge acceptance of the battery using 2% Yb and 2% Co coated nickel hydroxide reached 92% at 60 °C, where the charge acceptances for the un-coated and only cobalt coated ones were only 42 and 46%, respectively. It has shown that the Yb/Co coating is an effective way to improve the high temperature performance of nickel hydroxide for nickel–metal hydride batteries.
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High temperature performances of yttrium-doped spherical nickel hydroxide
Electrochimica Acta, 2004Co-Authors: X.p. Gao, Changyin Jiang, M.m Geng, Jie Yan, Chunrong WanAbstract:Abstract The regular and yttrium-doped spherical β-phase nickel Hydroxides were synthesized by means of chemically co-precipitation. The yttrium-doping with long needle-like nanocrystallites observed by TEM promoted the formation of the spherical nickel hydroxide with the larger diameter of about 5 μm. The discharge capacity of the yttrium-doped spherical nickel hydroxide was measured to be slightly lower than that of the regular spherical nickel hydroxide at room temperature. At temperatures of above 50 °C, however, the discharge capacity of the yttrium-doped nickel hydroxide is much higher than that of the regular spherical nickel hydroxide. The improvement of discharge capacity at elevated temperatures was contributed to the increase of the charge acceptance of yttrium-doped nickel hydroxide. The formation of an yttrium-rich surface layer on nickel hydroxide particles raised the oxygen evolution over-potential, leading to performance improvements of the nickel hydroxide electrode. The improvement of high temperature charge acceptance of yttrium-doped nickel hydroxide remarkably contributed to the high temperature charge–discharge efficiency of the nickel–metal hydride (Ni–MH) batteries with a commercial AAA size.
Farid Nasi Ani - One of the best experts on this subject based on the ideXlab platform.
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microwave assisted synthesis of metal oxide hydroxide composite electrodes for high power supercapacitors a review
Journal of Power Sources, 2014Co-Authors: Soheila Faraji, Farid Nasi AniAbstract:Abstract Electrochemical capacitors (ECs), also known as pseudocapacitors or supercapacitors (SCs), is receiving great attention for its potential applications in electric and hybrid electric vehicles because of their ability to store energy, alongside with the advantage of delivering the stored energy much more rapidly than batteries, namely power density. To become primary devices for power supply, supercapacitors must be developed further to improve their ability to deliver high energy and power simultaneously. In this concern, a lot of effort is devoted to the investigation of pseudocapacitive transition-metal-based oxides/Hydroxides such as ruthenium oxide, manganese oxide, cobalt oxide, nickel oxide, cobalt hydroxide, nickel hydroxide, and mixed metal oxides/Hydroxides such as nickel cobaltite and nickel–cobalt oxy-Hydroxides. This is mainly due to the fact that they can produce much higher specific capacitances than typical carbon-based electric double-layer capacitors and electronically conducting polymers. This review presents supercapacitor performance data of metal oxide thin film electrodes by microwave-assisted as an inexpensive, quick and versatile technique. Supercapacitors have established the specific capacitance (Cs) principles, therefore, it is likely that metal oxide films will continue to play a major role in supercapacitor technology and are expected to considerably increase the capabilities of these devices in near future.
Andrea Freitag - One of the best experts on this subject based on the ideXlab platform.
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fire retardant benefits of combining aluminum hydroxide and silica in ethylene vinyl acetate copolymer eva
Polymer Degradation and Stability, 2016Co-Authors: Rodolphe Sonnier, Amandine Viretto, Loic Dumazert, Marc Longerey, Sylvain Buonomo, Benjamin Gallard, Claire Longuet, Florian Cavodeau, Raphael Lamy, Andrea FreitagAbstract:The flame retardancy of ethylene-vinyl acetate copolymer filled with metal Hydroxides (aluminum hydroxide - ATH and magnesium hydroxide - MDH) and silica was investigated. Several composites containing only metal Hydroxides or a combination of metal Hydroxides and silica (ratio silica/hydrated filler = 0.18) were prepared and tested using pyrolysis-combustion flow calorimeter, thermogravimetric analysis and cone calorimeter at various heat fluxes. It was observed that silica provides benefits when the amount and other properties of the fillers allow the formation of an insulating mineral layer. In such cases, silica does not modify the first peak of heat release rate in cone calorimeter tests, but reduces or completely suppresses the breakdown of the insulating layer near the end of the combustion (assessed by the intensity of the second peak in the heat release rate as function of time). This effect is particularly obvious at lower heat flux, the insulating layer protects the underlying polymer, which is therefore not completely degraded.
Yushan Yan - One of the best experts on this subject based on the ideXlab platform.
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engineering the van der waals interaction in cross linking free hydroxide exchange membranes for low swelling and high conductivity
Chemsuschem, 2012Co-Authors: Jason Skovgard, Yushan YanAbstract:What a swell for Hydroxides: The typical trade-off between swelling control and ion conductivity in ion-conducting polymer membranes is overcome by enhancement of van der Waals interactions among polymer chains. Using a quaternary phosphonium-functionalized polymer, the simple combination of high electron density of the polymer and large dipole moment of the functional group leads to low membrane swelling, high hydroxide conductivity, and excellent hydroxide exchange membrane fuel cell performance.
Karel Vlassak - One of the best experts on this subject based on the ideXlab platform.
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phosphate sorption by synthetic amorphous aluminium Hydroxides a 27al and 31p solid state mas nmr spectroscopy study
European Journal of Soil Science, 1994Co-Authors: Richard Lookman, Pierre Grobet, Roel Merckx, Karel VlassakAbstract:Summary The sorption of phosphate on amorphous aluminium Hydroxides was investigated using 27Al and 71P solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, following the effect of different exposures to soluble phosphate. The spectra obtained were compared with the spectrum of amorphous aluminium phosphate. Aluminium in the unreacted hydroxide had a 100% octahedral co-ordination. When dried at 200°C and exposed to soluble phosphate, very little (maximum 0.1%) amorphous aluminium hydroxide transformed to a tetrahedral co-ordination (A1 bound by oxygen bridges to four P atoms), even after 120d. The tetrahedral co-ordination exists in aluminium phosphate gel, although most of its A1 atoms exhibit an octahedral co-ordination. For the aluminium hydroxide dried at 200°C, no formation of aluminium phosphate in which aluminium is in octahedral co-ordination could be detected, not even when the aluminium hydroxide was exposed to a phosphate solution for 120 d. We concluded that the formation of aluminium phosphate is restricted to the surface of the hydroxide. Most of the phosphate which is bound to the aluminium oxide however may not have formed a ‘bulk solid’ aluminium phosphate, but is adsorbed on the internal and external surface of the oxide. The same amorphous aluminium hydroxide, dried at 70°C instead of 200°C, is converted much more rapidly to aluminium phosphate when exposed to soluble phosphate. We propose a P-induced weathering mechanism to describe P sorption on amorphous aluminium Hydroxides at high P concentrations. In addition to NMR, phosphate adsorption experiments conducted on aluminium Hydroxides dried at different temperatures produced evidence that the porosity of the aluminium hydroxide aggregated particles can also be a factor controlling the rate of phosphate uptake from solution, if the aggregate is stable (is not resuspended) in solution.
