Biomass derived activated carbon based hybrid supercapacitors

Abstract

Supercapacitors with prestigious electrochemical performance have achieved exceptional worth however, a facile environmentally friendly approach is still desired for electrode material with high charge storage capability. In this study, we have demonstrated the facile synthesis of activated carbon (AC) and strontium phosphate (Sr3(PO4)2) (sonochemical approach) ) for energy storage applications. The surface morphology and crystal structure of the synthesized materials are investigated via performing X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The electrochemical performance of synthesized material is carried out in three electrode assembly. The Sr3(PO4)2 reveals utmost specific capacity of 220 Cg−1 at 0.5 Ag−1 whereas, the AC delivers the high specific capacitance of 319.41 Fg−1 at 1 Ag−1 respectively. This synthesized materials are further employed in an hybrid architecture for real device application. The Sr3(PO4)2 is utilized as positive and AC as negative electrode. The fabricated device delivers excellent specific energy of 25.4 Whkg−1 at specific power of 425 Wkg−1. The maximum specific power 1870 Wkg−1 is also achieved along with specific energy of 14.5 Whkg−1. The device reveals the excellent capacity retention of 90 % after 3000 GCD series. Furthermore, the kinetics of charge storage mechanism is studied for the device by applying Dunn's model and the diffusive and capacitive contribution in overall device capacity is investigated. Moreover, the power law is utilized to confirm the hybrid nature of the device by calculating the b values. The projected approach result in electrode materials that have delivered potential energy storage performance.