Improved surface charge storage properties of Prosopis juliflora (pods) derived onion-like porous carbon through redox-mediated reactions for electric double layer capacitors

Turning trash into treasure, the present work divulges the preparation of onion-like porous carbon derived out of the most malignant invasive weed, the Prosopis juliflora. The pods of the Prosopis juliflora are treated hydrothermally and chemically activated using KOH. The effect of activation temperature on the pore formation is investigated to obtain the desired porous carbon. The prepared porous carbon (J-800) has a significant specific surface area of 967 m(2) g(-1) with unique morphology of onion-like nanostructures and provided a sensible specific capacitance of 274 F g(-1) at 1.3 A g(-1) in H2SO4 electrolyte. Further, the performance of the device is effectually enhanced by adding KI as redox additive. Interestingly, the increased cell voltage (1.4 V) and improved cell capacitance of 588 F g(-1) is obtained. Ultimately, a superior energy density of 35.7 Wh kg(-1) at an enhanced power density of 971 W kg(-1) is also obtained in the redox additive based aqueous electrolyte. A detailed investigation of the surface storage mechanism is discussed, and the stability of the prepared super-capacitors is also demonstrated. Thus, the most eradicable eco-threat P. juliflora is successfully reformed into an efficient electrode material for the energy storage application.