Fabrication of heat-treated bulk copper for binder-free electrodes

A simple annealing method was applied to prepare agglomerated copper nanoparticles on a bulk copper current collector. Copper oxide electrodes were obtained by heat treatment of bulk copper at different temperatures and for different lengths of time. The effect of annealing temperature and time on chemical and surface structure was explored. XRD, XPS, FTIR and SEM were used for characterization of the structural, compositional and morphological properties of non-annealed and annealed copper. The electrochemical performance of the electrodes was examined in different electrolytes (neutral, alkaline and ionic liquid). Copper-based electrodes were annealed at 300 °C for 30 min and their specific capacitance at a scan rate of 5 mV s⁻¹ was calculated to be 1900 F g⁻¹. The electrochemical performance of annealed copper was not enriched by annealing the copper electrode for long durations because the electrochemical reaction of the copper oxide film occurs between the alkali and only the outmost surface of the annealed copper. The performance of the as-prepared copper oxide electrodes was attributed to the morphology of the electrode, not its thickness. The synthesis of copper oxide by annealing in a muffle furnace could provide an easy method for the production of copper-based electrodes for supercapacitor applications.