Unlocking the synergetic potential of cobalt iron phosphate and multiwalled carbon nanotube composites towards supercapacitor application

Abstract

To date, bimetallic phosphates have not been much explored in supercapacitor applications. Interestingly, these materials hold significant potential for energy storage due to the existence of multiple oxidation states and the presence of numerous phosphorus atoms, each contributing to a substantial number of electron clouds. Present research emphasises the electrochemical performance of composite electrodes consisting of multiwalled carbon nanotubes (MWCNTs) and cobalt iron phosphate (Co3Fe4(PO4)6). These electrodes have demonstrated exceptional performance and achieved a specific capacity of 3320 C g-1 (3688 F g-1) at a scan rate of 5 mV s-1 maintaining 87% stability even after 5000 cyclic voltammetry (CV) cycles. The electrochemical active surface area (ECSA) was estimated to be 700 cm2 for Co3Fe4(PO4)6 and 1625 cm2 for MWCNTs/Co3Fe4(PO4)6 composites. Additionally, the designed and tested large-area (10 x 4 cm2) liquid-configured symmetric device exhibited an impressive energy density (ED) of 52.3 W h kg-1 and power density (PD) of 3.5 kW kg-1. The fabricated device showed outstanding stability with a 98% capacity retention after 5000 cycles, reflecting the remarkable durability of the designed system. To illustrate its real-world applicability, the constructed device underwent a 10 s charging to power a DC fan for 110 s. Exploring non-toxic, multiple oxidation state iron phosphate (Co3Fe4(PO4)6) anchored MWCNTs with blossomed micro platelets surface architecture as a supercapacitive electrode and design of a large-scale (10 x 4 cm2) symmetric device powering a DC fan.