Preparation And Electrochemical Characterization Of Porous Novel Materials Composed By Copper And Cuprous Oxides

CuO is a p-type semiconductor with a narrow gap of 1.5 eV and a monoclinic system of space group C2h6 (C2/C). And it is widely applied on gas sensors, catalyst and electrode materials in Lithium-ion battles because of its photoconductive and photochemical properties. Among these transition-metal oxides, copper oxide is of particular interest for its inexpensiveness, nontoxicity and high capacity. The CuO exhibited reversible capacity 2-3 times larger than that of commercial graphite anode material and showed superior cycle performance. Some researches indicated that cuprous oxide might be good replacement for the carbon-baesd anode materials currently used in the Li-ion batteries, and it can also be used as solar cell material.Although many synthesis methods have been employed with copper oxides and other oxides, great challenges still exist in controlling their pore structures such as exorbitant activity of the precursor and destruction of the pore structures. In this thesis, a novel two-step method has been employed to synthesis copper oxides. Regular shaped precursors were first synthesis by a solution method. Regular pillow-shaped copper oxalate and bar-shaped copper citrate were synthesized by a solution route. Thermal treatment was carried out with the obtained precursor to produce porous cupric oxide. Porous Cu2O with pore size ranging were then obtained by reduction of the pillow-shaped porous CuO.XRD, SEM, TG-DTA and N2 physical adsorption-desorption measurements were applied to characterize the phase, morphology and pore structure of the samples. The results showed that:the oxides materials retain morphologies of their precursors. The morphology of the precursors is strongly affected by different copper sources and the reaction temperature. The pore characters depend strongly on the annealing temperature, heating rate and heating atmosphere during the second step. The hydrothermal temperature is the main factor for the component of Cu2O in the products.Performance tests were carried out using porous copper oxides (CuO and Cu2O) as the anode active materials in lithium battery. It shows that all the copper oxides exhibit charge/discharge performance. The porous CuO powder exhibited high average coulombic efficiency (98.3%) and capacity retention (83.3% of the discharge capacity of the second cycle after 50 cycles) at a current rate of 0.1 C. The first discharge and charge capacities were measured to be as high as 770.3 mAhg-1 and 374.2 mAhg-1, respectively.