Blossoming of Multivalent Iron Phosphate Microplatelets Grown on Multiwall Carbon Nanotube Frameworks: Investigation of Supercapacitive Performance through Symmetric and Asymmetric Configurations

The present study explores the impact of non-toxic and higher oxidation state iron phosphate-blossomed microplatelets [Fe7(PO4)6] anchored on multiwall carbon nanotubes (MWCNTs) toward supercapacitor applications, which is not only the first report for the synthesis of Fe7(PO4)6 by chemical bath deposition but also for the design of symmetric and asymmetric supercapacitive devices. “Dip and dry” coated MWCNTs on the copper have been employed as the substrate to fabricate the Cu/MWCNTs/Fe7(PO4)6 electrode. Interestingly, the designed Cu/MWCNTs/Fe7(PO4)6 electrode exhibited superior capacitance (727 F/g) compared to bare MWCNTs (49.8 F/g) and Fe7(PO4)6 (147.8 F/g) at 100 mV/s scan rate. The standalone electrode has been well optimized through diverse characterizations followed by the fabrication of a symmetric device in an aqueous KOH electrolyte yielding 227 F/g specific capacitance, whereas an asymmetric solid-state device assembled using Cu/MWCNTs/Fe7(PO4)6 and SS/MWCNT electrodes with a conducting KOH electrolyte embedded in a non-conducting PVA polymer matrix yielding 163 F/g. Complete studies of symmetric and asymmetric devices have been incorporated herein.