Exploring the Energy Storage Potential of Organic Molecule-Stabilized Cobalt(II) Ferrocyanide Nanoparticles

Supercapacitors have received significant interest as advanced energy storage solutions because of their high value of specific capacitance, power density, and extended cycle life. Cobalt-based compounds are naturally abundant and have good electrical conductivity, which makes them ideal for supercapacitor applications. In this work, ultrafine cobalt-(II) ferrocyanide (CFC) particles were produced using a complexation-mediated synthesis route and analyzed through surface, microscopic, and optical characterization techniques. In a three-electrode setup using CFC as the working electrode, the cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) techniques delivered specific capacitance values of 525 F g^-1 at 3 mV s^-1 and 435 F g^-1 at 6 A g^-1, respectively. Additionally, a hybrid supercapacitor device was built with CFC as the cathode and activated carbon serving as the anode electrodes, respectively, demonstrating specific capacitance values of 44 F g^-1 at 3 mV s^-1 and 51 F g^-1 at 0.5 A g^-1. The device preserved 96% of the initial capacitance with a Coulombic efficiency of 98% after 3000 GCD cycles with a maximum energy and power density of 28 W h kg^-1 and 2800 W kg^-1, respectively. Furthermore, two CFC-based hybrid devices, each charged at 1 A g^-1, were linked in series to illuminate a red LED for a duration of 90 s.