Thermal treatment induced improvement on the capacitive performance of cobalt oxide nanocubes

کد مقاله : 1062-CNF

نویسندگان

نیکان افصحی *، نعیمه ناصری، علی ساجدی مقدم دانشگاه صنعتی شریف

چکیده مقاله

With the increasing demand for high-performance energy storage devices, supercapacitors have been widely studied due to their high power density and long lifespan.1,2 Cobalt oxide (Co3O4) nanostructures have received considerable attention to be used as an active electrode material by offering significant advantages of high specific capacitance, strong redox ability, and stable cycle performance in alkaline electrolytes.3,4 Despite these merits, there is still plenty of room to further improve their supercapacitive performance. In this study, we investigate the impact of thermal treatment on enhancing the energy storage capability of Co3O4 nanocubes. Co3O4 was synthesized by a facile and cost-effective hydrothermal method. The SEM observation shows well-distributed Co3O4 nanocubes with an average size of 30 nm. In addition, the energy-dispersive X-ray spectroscopy (EDS) mapping reveals the homogenous distribution of Co and O elements. The small size and cubic morphology make the Co3O4 appropriate electrode for supercapacitor application by providing a larger available surface area. To explore the capacitive performance of Co3O4 nanocubes, galvanostatic charge/discharge (GCD) measurement was carried out in a 3 M KOH electrolyte. The gravimetric capacitance of the Co3O4 was calculated to be 520 F g-1 @ 1 A g-1. We next set forth to investigate the impact of thermal treatment on the capacitive performance of Co3O4 under different annealing temperatures of 450 °C, 650 °C, and 750 °C. As can be seen, at 450 °C the capacitance reaches its highest value of 950 F g-1@ 1 A g-1. This can be assigned to the improvement in the crystallinity of the material. However, further increasing the temperature results in a decrease in capacitance. Through SEM characterization, we noticed that higher temperatures can pose morphological deviation from the cubic structure by fusing cubes together and formation bigger undefined structures, which reduces the available surface area for electrode-electrolyte interaction. This study demonstrates the impact of thermal treatment on the capacitive performance of Co3O4 nanocubes and exhibits the optimum thermal conditions to extract the best capacitance from this promising material.

کلیدواژه ها

Energy storage, Supercapacitor, Cobalt oxide nanocubes, Thermal treatment

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