Caracterização estrutural e eletroquímica de cobaltita de cálcio como cátodo de célula a combustível de óxido sólido

Abstract

In the last decades, mainly due to the advent of new technologies, with the exponential growth of the population, the intensification of the use of fossil fuels has generated great impacts to the environment. In this scenario, the search for energy alternatives has been constant. A rising solution is the use of the fuel cell technology, which has the principle of converting chemical energy into electrical energy. This work aimed to study calcium cobaltite as a potential cathode material for solid oxide fuel cells (SOFC). Powders of composition Ca3CuxCo4-xO9-d (0 = x = 0.15) were obtained using the Pechini method modified by using gelatin. The obtained powders were calcined at 900 °C for 2 h and characterized by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The lattice parameters were determined by Rietveld refinement of the diffraction data. The electrochemical characterization was performed under open circuit conditions and under cathodic polarization using a 3 electrode configuration. The results of XRD and SEM indicated the attainment of particles of Ca3CuxCo4-xO9-d solid solutions free of secondary phases and in the format of microplates up to 5 m in diameter. The electrochemical results highlight the potential of calcium cobaltite as a cathode material of SOFC, presenting total polarization resistance (Rp of 2.8 ? cm2 at 700 ° C in oxygen) competitive with cobaltites from literature and low values of cathodic polarization (123 mV at 700 ° C and 100 mA/cm2) in comparsion to alternative cathodes for SOFC.