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This paper discusses a pulse electroplating method for preparing copper (Cu)-coated gas diffusion electrodes (GDEs) for the electrochemical conversion of carbon dioxide (CO2) to hydrocarbons such as ethylene. Ionomer coating and air-plasma surface pre-treatments were explored as means of hydrophilizing the carbon surface to enable adhesion of electrodeposited material. The pulsed-current electrodeposition method used successfully generated copper and copper oxide micro- and nano-particles on the prepared surfaces. Copper(I) species identified on the ionomer-treated GDEs are presumed to be highly active for the selective generation of ethylene as compared to other gaseous byproducts of CO2 reduction. Conversely, copper catalysts deposited onto plasma-treated GDEs were found to have poor activity for hydrocarbon production, likely due to substantial metallic character. Of note, plasma treatment of an ionomer-treated GDE after copper plating yielded further improvements in catalytic activity and durability towards ethylene production.
Multilayer films formed from Al2O3 and TiO2 by atomic layer deposition were systematically studied. The relationship between the electrical characteristics of the films and the type of oxidizer used for the Al2O3 layers was investigated. The results indicated that oxygen defects in TiO2 layer and a highly insulating Al2O3 layer are necessary for realizing a giant dielectric constant and a low dielectric loss. A high electrical resistance of 1.7×108 Ω / diameter of 1 mm and a dielectric constant of 1140 were achieved at 100 Hz by suitable choice of oxidizer for the Al2O3 layer.
Specific demand of lightweight and high efficient flexible energy unit is increased day by day for its integration into bendable electronics devices. Super-capacitor is one of the promising power unit to meet the current requirement. Flexible metal oxide and polypyrrole based flexible electrode materials are prepared using electrodeposition. The calculated specific capacitances of the devices shows 0.5 mill farad per gram. The super-capacitor is ultra-flexible, stable with operational voltage window expands from 0.8 to 2.5 V which can help to reduce the number of super-capacitor in series connection to obtain the same output. In this study, a conductive polymer can be coupled with MnO2 to improve capacitance and conductivity of a hybrid structure based on MnO2.
Lithium solid electrolyte with NASICON structure in the form of Li1+2xAlxTi2−xSixP3−xO12 solid solution has been prepared by high temperature solid state reaction using low cost kaolin as the starting material. The crystal structure of the solid solution was investigated by powder X-ray diffraction. The AC impedance measurements indicate that ionic conductivity increased by more than one order of magnitude when a small amount of Al3+ and Si4+ ions were incorporated into the LiTi2(PO4)3 crystal structure. The significant improvement on ionic conductivity can be attributed to the increased interstitial Li+ ions in the crystal structure. The highest ionic conductivity was found in Li1.2Al0.1Ti1.9Si0.1P2.9O12: 8.3 x 10-5 S·cm-1 at room temperature (21°C) and 1.5 x 10-3 S·cm-1 at 100°C.
The phase diagram of LiF-Li3PO4 system is studied. The eutectic coordinates are 800±5°C, 8±1 mol% Li3PO4. A region of a solid solution based on lithium phosphate with a length of up to 11±2 mol% LiF was discovered. It is assumed that there is heterovalent isomorphism where anionic tetrahedron (PO4)3- is replaced by tetrahedron (LiF4)3-.
Amorphous LiCoO2-based positive electrode materials are synthesized by a mechanical milling technique. As a lithium oxy-acid, Li2SO4, Li3PO4, Li3BO3, Li2CO3, and LiNO3 are selected and milled with LiCoO2. XRD patterns indicate that reaction between LiCoO2 and these lithium oxy-acids proceeds. Amorphization mainly occurs, and several broad peaks attributable to cubic LiCoO2 are observed in all the samples. These amorphous active materials show mixed conductivities of electron and lithium ion. All-solid-state cells using the prepared amorphous active materials and the Li2.9B0.9S0.1O3.1 glass-ceramic electrolyte are fabricated and their charge-discharge properties are examined. The cells with only the 80LiCoO2·20Li2SO4 (mol%) and the 80LiCoO2·20Li3PO4 active materials function as secondary batteries. This is because higher lithium ionic conductivities are obtained in the 80LiCoO2·20Li2SO4 and 80LiCoO2·20Li3PO4 active materials than in the others. The largest capacity is obtained in the cell with the 80LiCoO2·20Li2SO4 active material because of its good formability and high lithium ionic conductivity. In addition, the cell with the 80LiCoO2·20Li2SO4 positive electrode active material shows the better cycle and rate performance than that with the crystalline LiCoO2. It is noted that the amorphization with lithium oxy-acids is a promising technique for achieving a novel active material with better electrochemical performance.