SnO-SnO2 film on carbon steel cycling in a choline chloride-based ionic liquid electrolyte for energy storage devices

Sn-based film was synthesized cathodically on a high-carbon steel surface in a non-aqueous deep eutectic solvent-based ionic liquid electrolyte. The electrochemical properties of the resultant coatings in Ethaline ionic liquid were also investigated. The composition and morphology of the Sn-based films, as dependent on the cycling potential in Ethaline, were revealed. The characterization showed that SnO and SnO2 predominated at the reduced and oxidized potentials, respectively. The microstructure of the SnO and SnO2 films was also changed according to cycling potential. The electrochemical performances of the films were measured in Ethaline with regard to supercapacitor applications. The rate limiting reaction between Ethel ine and the tin oxide electrode followed a purely diffusional-control led mechanism. The Sn-based film on steel had a specific capacitance of 23 F g(-1) at 5 mV s(-1). Specific capacitance retention has a long lifecycle and stability, even after 200 scans. The experimental results demonstrated that the Sn-based oxide coating could be used as an energy storage electrode in a deep eutectic solvent electrolyte.