Studying activated carbons of natural sources for supercapacitor applications

Abstract

Activated carbon (AC) can be produced from natural sources such as pistachio and acorn shells, which can be an inexpensive and good use of natural waste, and used in energy storage devices, such as supercapacitors. The carbonaceous materials used in this thesis were carbonized at two high temperatures, 700°C and 900°C. Carbonized nutshells were chemically activated using 1 wt% potassium hydroxide (KOH). Activated carbon powders with polyvinylidene fluoride (PVdF) were used to construct carbon electrodes. 1M of tetraethylammonium tetrafluoroborate (TEABF4) and propylene carbonate (PC) were used as electrolytes. Electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for characterization of the supercapacitors. Scanning electron microscopy (SEM) was used to inspect the surface texture of the activated carbons. Activated pistachio and acorn shells carbonized at 700°C showed more porous surface texture than those carbonized at 900°C. Carbonization temperature effects were studied for their electrochemical characteristics. Pistachio and acorn shells carbonized at 700°C showed better electrochemical characteristics than those carbonized at 900°C in their use as electrode materials. Results indicated approximately 50,000 μF/g and 27,083 μF/g specific capacitance for activated acorn and pistachio carbons, respectively, at a scan rate of 10 mV/s. Acorn and pistachio shells showed approximately 80% and 60% carbon yield, respectively. This study showed promising results for using these activated carbons produced from natural waste for supercapacitor applications. Activated pistachio and acorn shells carbonized at 700 degrees C showed more porous surface texture than those carbonized at 900 degrees C. Carbonization temperature effects were studied for their electrochemical characteristics. Pistachio and acorn shells carbonized at 700 degrees C showed better electrochemical characteristics than those carbonized at 900 degrees C in their use as electrode materials. Results indicated approximately 50,000 ?F/g and 27,083 ?F/g specific capacitance for activated acorn and pistachio carbons, respectively, at a scan rate of 10 mV/s. Acorn and pistachio shells showed approximately 80% and 60% carbon yield, respectively. This study showed promising results for using these activated carbons produced from natural waste for supercapacitor applications.