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Li metal has been a promising anode material for high-energy-density batteries because of its ultrahigh theoretical capacity, but its practical application is hindered by serious dendrite growth and volume change. Herein, NiO nanoarrays are grown on a porous Ni skeleton derived from phase inversion method for stabilizing Li metal. The lithiophilic NiO nanoarrays decrease Li nucleation barrier and local current density, and provide abundant sites for nucleation. The Ni skeleton with vertical channels and interconnected small pores, not only provides Li storage space and ion channels, but also alleviates top-surface deposition and improved uniformity of Li distribution. As a result, the half cells comprising the NiO nanoarrays-modified Ni skeletons demonstrate a high Coulombic efficiency of 98.8% under 4 mAh cm-2 over 210 cycles (>1700 h), and the symmetric cells show much reduced voltage hysteresis and prolonged lifespan (>2000 h) under a capacity of 5 mAh cm-2 and a current density of 2 mA cm-2. Full cells with LiFePO4 as cathodes delivered a capacity retention of 79.4% after 500 cycles at 2 C and excellent rate capability at 10 C, shedding a fresh light on an effective strategy for the practical application of Li metal batteries. [ABSTRACT FROM AUTHOR]

The structure-property relationship of Fe-doped SrCoO3-δ was studied. With increase of Fe content in SrCo1-xFexO3-δ from x=0 to x=0.2, the phase composition changed progressively in the order of hexagonal→brownmillerite (main)+hexagonal→cubic (main)+ brownmillerite→single cubic phase. Transition between the hexagonal/brownmillerite phase and the cubic phase took place with variation of the operating conditions, and was associated with remarkable changes in the electrical conductivity and oxygen permeation flux [ABSTRACT FROM AUTHOR]

Brittleness is the main obstacle for commercial implementation of ceramic hollow fiber membranes. Here we report the reinforcement of porous alumina hollow fiber membranes by using commercial SiC nanofibers. The SiC reinforced alumina hollow fiber membranes were produced by the polymer-assisted phase inversion method and subsequent removal of the polymer and sintering at high temperatures. The effects of the amounts of SiC nanofibers (2.5-10.0 wt%) on the mechanical strength, microstructure and water flux of the hollow fiber membranes were investigated. The results showed that without addition of SiC nanofibers, the maximum bending strength was about 154 MPa for the porous alumina hollow fiber sintered at 1510 °C However, the maximum bending strength of the reinforced membrane reached 218 MPa, in which 5 wt% SiC was incorporated and sintered at 1450 °C; in other words, a 40% improvement in bending strength was achieved. After being sintered at 1450 °C, the 5% SiC reinforced membrane exhibits a porosity of 41.7% and a peak pore size of 1.35 μm whereas the pure alumina membrane has a porosity of 37.5% and a peak pore size of 1.25 μm; the former shows a water permeability of 7.99 L m-2 h[sup -1] kPa-1, which is 3.3 times higher than that of the latter. Therefore, the ceramic nanofiber reinforcement is promising for the development of high-performance ceramic hollow fiber membranes for practical applications. [ABSTRACT FROM AUTHOR]

The oxygen transport in the nickel-zirconia composite was investigated using the oxygen permeation method. A disk-shaped sample made of nickel (40 vol%) and yttria-stabilized zirconia (YSZ) was used to construct a permeation cell. By exposing one side of the sample to a CO2 gas stream and the other side to a CO stream at elevated temperatures, oxide ions were extracted from CO2 and transported to the other side to oxidize CO. The oxygen permeation flux through the composite was determined by analyzing the effluent from the permeation cell, and the oxygen ionic conductivity of the composite was derived from the permeation data and the oxygen partial pressures. It was shown that the oxygen ionic conductivity of the composite YSZ fraction was about one third of that for the single-phase zirconia ceramic, and the activation energy associated with the transport of oxide ions in the composite is somewhat greater than that of the single-phase zirconia. [ABSTRACT FROM AUTHOR]

The negative temperature coefficient material with low thermal constant B and high resistivity were explored for low-temperature thermistor applications. The spinel oxide Fe0.5Cu0.2Ni0.66Mn1.64O4 had a required low B value, but its resistivity was much lower than the required value. To increase the resistivity, yttrium-stabilized zirconia (YSZ) was introduced into the spinel oxide. The spinel oxide in composite with YSZ (80 mol%) exhibited a much increased resistivity (10 479 Ω·cm at 25°C) while without causing much change in the B value (2842 K). It was found that the electrical conduction of the composite can be described quantitatively using the percolation theory. [ABSTRACT FROM AUTHOR]

Abstract  Effect of thermal history and chemical composition on aging of Ni x Mn3 − x O4 +  δ (0.56 ≤ x ≤ 1.0) ceramics was investigated. It was found that all the Ni x Mn3 − x O4 +  δ ceramic samples metallized by co-firing at 1050°C showed significant electrical stability with an aging coefficient less than 1.0%, while aging of those metallized by annealing at 850°C was increasingly serious with a rise in Ni content x, the aging coefficient ranging from 0.2% to 3.8%. However, the ceramic samples with Ni content x ≤ 0.70, whether metallized by co-firing or by annealing, exhibited extraordinarily high electrical stability with an aging coefficient less than 0.5%. The composition dependence of aging of the ceramic samples was explained qualitatively, based on the electrical conduction mechanism of small polaron hopping and on the aging mechanism of the cationic vacancy-assisted migration of cations to their thermodynamically preferable sites under thermal stress. [ABSTRACT FROM AUTHOR]

The article proposes a membrane-based coal-combustion process, which results in a carbon dioxide-rich gas stream. The process involves the gasification of coal by carbon dioxide, and the burning of carbon oxide with oxygen supplied by a dense ceramic membrane from air. Efficient and convenient separation of carbon dioxide and clean utilization of coal are enabled because the resulting exhaust gas stream is rich carbon dioxide. The study suggested further research and development to improve the reaction kinetics of carbon dioxide with coal.

A tubular membrane made of Zr0.8Y0.2O1.9 (60 vol%) and was prepared by a standard ceramic process. Oxygen permeation through the membrane tube was examined by exposing its outer shell to air and sweeping its inner wall with pure helium or CO balanced with helium. An oxygen flux of 9.2×10−9 mol cm−2 s−1 was measured at 950°C under air/He gradient, and a larger flux of 3.2×10−8 mol cm−2 s−1 at 930°C under air/CO gradient. The membrane tube was found to exhibit excellent stability under highly reducing atmosphere and elevated temperatures. The oxygen permeation rate is likely to be increased through the modification of the surface and reduction of the membrane thickness. [ABSTRACT FROM AUTHOR]

A solid-state coordination reaction was adopted to prepare negative temperature coefficient ceramics. A mixed oxalate NiMn2(C2O4)3·6H2O, a coordination compound, was synthesized by milling a mixture of nickel acetate, manganese acetate, and oxalic acid for 5 h at room temperature. An ultrafine NiMn2O4 powder was obtained by calcining the mixed oxalate in air at 850°C for 2 h. Ceramics with a relative density of more than 97% were achieved by sintering powder compacts at a temperature as low as 1050°C for 5 h. The specific electrical resistivity ρ25°C and the thermal constant B25°/85°C were 2174 Ω·cm and 3884 K, respectively. The drift of the resistivity after aging at 150°C for 1000 h was 3.0%. [ABSTRACT FROM AUTHOR]