Nitrogen and sulfur-rich cobalt complex for hybrid supercapacitor applications

In the quest for more effective and advanced energy storage devices, an integrated methodology combining both battery and supercapacitor hybrid features is being explored. In this regard, we have developed a cobalt-1,10-phenonthroline complex with 5-sulfoisopthalic acid in the lattice (Co-Phen@SIP) via sonication method. Structural properties were explored by Single-crystal XRD, Elemental analysis, TGA, FTIR, UV Visible and Fluorescence spectroscopy while detailed electrochemical study was carried out via CV, GCD and EIS. Three electrode setup revealed pseudocapacitive properties of Co-Phen@SIP with specific capacity of 157.6 Cg(-1) at 2 A g(-1). Battery-supercapacitor hybrid device showed energy density and power density of 13.03 Wh kg(-1) and 3309 W kg(-1) respectively. The device also exhibited remarkable columbic efficiency of 98.94 % even after 5000 GCD cycles. Theoretical approach based on Dunn's model and power law was also applied to check the capacitivediffusive contributions of three-electrode system and hybrid device. 1, 10-phenonthroline induces structural stability over long cyclability. The introduction of SIP in Co-complex caused charge transfer through pi center dot center dot center dot pi interactions providing porous and robust structure which aided in improved electric conductivity and ionic mobility. This multi-ligand chemistry with the redox active cobalt has achieved superior performance and reversibility in comparison to other traditional complexes. The idea came out to be an effective strategy for advanced hybrid supercapacitors.