Study on Co3O4 and NiCo2O4 films deposited through solution precursor thermal spray routes for supercapacitor application

In order to efficiently utilize green novel energy, supercapacitors as one of the most interesting energy storage devices have been paid many increasing attentions. Electrodes in capacitor are key components for a high efficiency. Based on conventional techniques (e.g. sol-gel, hydrothermal), the metal oxide electrodes are usually prepared from nanopowders, requiring multi-step, long duration and usage of binder. Among different metal oxides, spinel Co₃O₄ and nNiCo₂O₄ as electrodes are considerable attractive due to their excellent electrochemical characteristics, low toxicity and low cost. In this study, Co₃O₄ and NiCo₂O₄ related electrode films were deposited directly on current collectors through rapid one-step solution precursor thermal spray processes, including “Solution Precursor Plasma Spray” and “Solution Precursor Flame Spray”. The effects of stand-off distance and solvent types on Co₃O₄ films were studies. For the different NiCo₂O₄ films, different ratios of Ni/Co in the raw solutions were employed. The phase composition and surface morphologies of electrode films were characterized by XRD, Raman and SEM analysis. The porous films with high surface area were obtained. The following electrochemical tests demonstrated a specific capacitance as high as ∼1240 F g⁻¹ with a retention capacity of 80.8% after 1000 cycles at 20 mV/s in 2 M KOH electrolyte.