Walnut shell derived mesoporous activated carbon for high performance electrical double layer capacitors

In the present work a facile conversion of Walnut shells, the biowaste into porous activated carbon (Wn AC) at different activation temperature was proposed. Further, walnut shells derived activated carbon obtained at 600, 700 and 800 degrees C such as Wn-600, Wn-700 and Wn-800 were used as electrode material for supercapacitor. The cyclic voltammetry, galvanostatic charge-discharge measurements and electrochemical impedance analysis were performed to predict the capacitive properties of the fabricated Wn-600@ Ni, Wn-700@ Ni and Wn800@ Ni foil electrodes. Owing to the excellent morphological feature the Wn-800 sample showed a higher specific capacitance value (595 F/g at a current density of 1 A/g) than the rest of the samples. Furthermore Wn-800@ Ni electrode exhibited 91% of its capacitance retention value upto 6000 GCD cycles at the current density of 3 A/g. Hence, porous walnut shell derived AC samples were identified as the promising electrode material for energy storage devices.

Automated summary

This study presents a facile method to convert walnut shells into porous activated carbon for supercapacitor applications. It was found that activated carbon obtained at different activation temperatures exhibited variations in performance, with the sample produced at 800 degrees Celsius showing the highest specific capacitance and cycle stability.