Nickel/Cobalt/Tin ternary composite: Composition influence on the electrochemical properties

This work reports the influence of the composition in the charge storage properties of the Ni-Co-Sn ternary composite. Ternary oxide composites were synthesized by polymeric precursor’s method at different compositions of precursor metals salts. Scanning electron microscopy images revealed different levels of cracks in the surfaces of the obtained composite. X-ray diffraction analysis of the composites revealed that, independently of the composition, they are formed by the NiCo2O4, Co2SnO4, Co3O4 and NiO cubic phases. Electrochemical techniques including cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy were used to estimate the electrochemical performance of composites. The voltammograms revealed that the mixture with a greater amount of nickel favored the specific capacity, obtaining a maximum exclusively by faradaic reactions on electrode surface. The charge-discharge galvanostatic technique showed a capacitance retention varying in the range of 76–87% over 1000 cycles for the different obtaining conditions. The electrochemical impedance spectroscopy was used to determinate the relaxation time constant values for the different compositions, resulting in 0.6 ms and 5.6 ms for the Co50 and Ni50, respectively. In the case of Sn50, the time constants associated with the two identified charge transfer processes were 1.4 ms and 113 ms.