Study of Annealing Temperature on Electrochemical Properties of Nsutite Materials*

The demand for energy storage devices is continuously increasing due to the need to store energy produced from renewable energy sources and technology advancement in portable electronic devices, power tools, and hybrid/electric vehicles. Rechargeable batteries, fuel cells, and supercapacitors are considered as energy storage devices (ESDs). Supercapacitors, due to their high-power density compared to Li-ion batteries, can be used for high power applications. Transition metal oxides such as RuO₂, MnO₂, CuO, etc. can be used as electrode materials for supercapacitor applications. Among these, MnO₂ is considered as an excellent candidate for supercapacitors. MnO₂ can be obtained from from nsutite, an ore found in a town called Nsuta in Ghana. In our previous studies, we found that pure nsutite materials showed the electrochemical behavior. To further study the effect of annealing temperature on electrochemical behavior of nsutite, we annealed ball milled nsutite materials at different temperatures.  The specific capacitance of ball milled nsutite material was calculated to be 36 F/g at 0.5A/g current density. The specific capacitance of the ball milled samples annealed at 350^oC and 580^oC was 18 F/g and 11.3 F/g, respectively at a current density of 0.5 A/g.