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Abstract: A nano-flake network cobalt hydroxide and well-ordered hexagonal mesoporous silica SBA-15 molecular sieves nanocomposite materials (designated as Co(OH)2/SBA-15) for electrochemical capacitor electrode have been prepared using a liquid-precipitated method. The electrochemical capacitance characterization of the Co(OH)2/SBA-15 materials was performed using cyclic voltammetry, chronopotentiometry, and impedance spectroscopy, respectively. These nano-flakes cobalt hydroxide maintain high utilization at high rates of discharge. A maximum specific capacitance of 467.5Fg−1 can be achieved in 2M aqueous KOH with the potential range from −0.2 to 0.4V (vs. SCE) in a three-electrode glass cell at room temperature for the Co(OH)2/SBA-15 electrode, suggesting its potential application in electrochemical capacitors. Furthermore, the effect of annealing temperatures on the electrochemical capacitance characteristics has also been explored. [Copyright &y& Elsevier]

Current data allocation algorithms neglect the problems of unsatisfactory allocation results and long execution time caused by the redundancy of full comparative data and the complexity of data types. To solve these problems, a real-time allocation algorithm of full comparison data based on storm is proposed. Firstly, the phase unwrapping algorithm of minimum spanning tree is used to remove redundant data in full comparison data; then, the distributed data clustering algorithm and storm framework are used to realize the full comparison data clustering after redundancy removal. Several main factors affecting the selection of statistical information are summarized according to the clustering results. Then the communication cost of data loading and transaction processing is determined, and the trade-off between read-only transaction and update transaction cost is achieved. By judging whether the total cost of read-only transaction and update transaction is reduced or not, the replica is eliminated, and a full comparison data allocation algorithm with minimum total cost of read-only transaction and update transaction is proposed to realize real-time allocation of full-comparative data. The example analysis shows that the proposed algorithm can meet the user's needs in terms of execution time, acceleration ratio, storage efficiency and cost. Compared with the reference algorithm, the proposed algorithm has the lowest execution time, the highest acceleration ratio and the closest allocation cost to the ideal overhead. [ABSTRACT FROM AUTHOR]

Abstract: Nano-thin polypyrrole (PPy) layers were coated on chemically modified ordered mesoporous carbon (m-CMK-3) by an in situ chemical polymerization. Structural and morphological characterizations of m-CMK-3/PPy composites were carried out using field emission scanning electron microscopy. Pseudo-capacitive behavior of the deposited PPy layers on m-CMK-3 was investigated by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. As results of this study, the thin layer of PPy in the composite electrode was effective to obtain fully reversible and very fast Faradaic reaction. A maximum discharge capacity of 427Fg−1 or 487Fg−1 after correcting for weight percent of PPy phase at the current density of 5mAcm−2, could be achieved in a half-cell setup configuration for the m-CMK-3/PPy composites electrode, suggesting its potential application in electrode material for electrochemical capacitors. [ABSTRACT FROM AUTHOR]

Nanocomposites consisting of mesoporous carbon CMK-3 and cobalt hydroxide nanoflakes are synthesized by a chemical precipitation method. The successful growth of nanometer-sized Co(OH) flakes on the surface of CMK-3 is confirmed by scanning electron microscopy. The Co(OH)/CMK-3 composite electrodes are investigated for its use in the electrochemical capacitors with cyclic voltammograms, chronopotentiometric measurements, and electrochemical impedance spectroscopy. Experimental studies reveal that the Co(OH)/CMK-3 composite electrode with the 20 wt.% CMK-3 presents excellent electrochemical performance with specific capacitance of 750 F/g (or 910 F/g after being corrected for the weight percentage of the Co(OH) phase). The overall improved electrochemical behavior accounts for the unique structure design in the Co(OH)/CMK-3 composite in terms of porous nanostructure, large specific surface area, and good electrical conductance. The Co(OH)/CMK-3 composite electrode also shows better rate capability and cyclic stability, suggesting its potential applications as the electrode materials for electrochemical capacitors. [ABSTRACT FROM AUTHOR]

Abstract: Hierarchically porous composite materials consisting of nanoflake-like nickel hydroxide and mesoporous carbon are synthesized by a facile chemical precipitation method. The effects of microstructure and morphology of the carbon support on the electrochemical properties of the composite are also investigated. Structural characterizations have revealed that nanometer-sized nickel hydroxide nanoflakes can grow on the surface of mesoporous carbon supports. The mesoporous carbon-based composites shows better structure with interlaced nanoflakes and higher specific capacitance than activated carbon-based composite. The composite material with mesoporous carbon morphology of large particle size and long channel lengths possesses the highest specific capacitance of 2570F/g, suggesting its potential applications as the electrode materials for electrochemical capacitors. The overall improved electrochemical behavior can be attributed to the unique structure design in nickel hydroxide/mesoporous carbon composite in terms of its nanostructure, large specific surface area and good electrical conductance. [Copyright &y& Elsevier]