| Abstract [eng] |
Design of high efficiency energy accumulators has recently become an important issue of science and technology. Electrochemical capacitors are distinguished for a greater power, a longer self-discharge time and a greater number of work cycles as compared to those of traditional electrochemical batteries. Effective supercapacitors are mainly produced of RuO2, which is distinguished from other metals for its nearly highest specific capacity, however its practical application is limited by its high price, therefore efforts are under way to find cheaper substitutes. Recently cobalt oxide has been intensively studied. It is important to find economically effective and simple methods which will make it possible to increase the pseudocapacities of cobalt oxides. The conditions of electrochemical cobalt deposition, under which the fiber Co nanostructure possessing a great surface area is formed, have been determined in the work. Cobalt hydro/oxide layers were formed by the anodic polarization method and their pseudocapacity was studied on various substrates: nanostructured, magnetron-sputtered coating and metallurgical cobalt. The pseudocapacitor behaviour of cobalt hydro/oxides was studied by using the cyclic voltammetry method along with electrochemical quartz crystal mocrobalance (EKKM). Oxide layers showed oxidation-reduction and corresponding pseudo-capacitor behaviour.It has been shown that the oxide layer is stable and it withstands a few thousand polarization cycles. It has been established that the capacity of oxides formed on the nanofiber structure is fivefold higher as compared to that of oxides formed on metallurgical Co. A new method of formation of cobalt oxide, possessing very good pseudo-capacitor characteristics has been proposed. The principle of this method implies formation of the Co(OH)2–CoS composition and its annealing at a high temperature. CoS inclusion into Co(OH)2 increases the capacity about threefold. |
