Desenvolvimento e caracterização de filmes bicamadas de Ni(OH)2 e CoOOH para aplicação em dispositivos de armazenamento de energia

Abstract

The present work presents and discusses the results concerning the electrochemical syntheses of CoOOH-Ni(OH)2 bilayer films. For this, different conditions of electrodeposition of the simple components Ni(OH)2 and CoOOH were studied. In the case of Ni(OH)2 deposition, the influence of the electrodeposition temperature on the electrochemical response of the films was studied from the deposition to 5 oC, 10 oC, 15 oC, 20 oC and 25 oC . By means of the Cyclic Voltammetry the different contributions in the charge stored in the material were determined. As a result, it was found that in the films deposited at 10 oC, both the innermost areas of the material, as well as the external ones, participate in the charge storage process, obtaining high capacitance values of 2549 F g-1. In the CoOOH films, the influence of the substrate on the performance of the material was studied. For this the films were deposited in Ti plates, steel plates and steel mesh. The films deposited on a steel plate showed superior electrochemical performance with high capacitance values of 614,3 F g-1 and a stability of 92,6% after 1000 cycles of Cyclic Voltammetry. Taking into account the best conditions of obtaining simple films, CoOOH-Ni(OH)2 bilayer films were developed from the electrochemical oxidation of Co(OH)2 and Ni(OH)2 films used as precursors. The characterization from Raman Spectroscopy showed the effective conversion of Co(OH)2 to CoOOH, with preservation of Ni(OH)2. The bilayer films showed high electrochemical performance as a result of the synergy between the components. Capacitance values of 1795 F g-1 at 1,0 mA cm-2 and capacitance retention of 96,82 % at 10 mA cm-2 were relevant characteristics of bilayer films, making these a promising material in the application as electrode for energy storage devices.