Prussian Blue Anchored on Reduced Graphene Oxide Substrate Achieving High Voltage in Symmetric Supercapacitor

In this work, iron hexacyanoferrate (FeHCF—Prussian blue) particles have been grown onto a reduced graphene oxide substrate through a pulsed electrodeposition process. Thus, the prepared FeHCF electrode exhibits a specific volumetric capacitance of 88 F cm⁻³ (specific areal capacitance of 26.6 mF cm⁻²) and high cycling stability with a capacitance retention of 93.7% over 10,000 galvanostatic charge–discharge cycles in a 1 M KCl electrolyte. Furthermore, two identical FeHCF electrodes were paired up in order to construct a symmetrical supercapacitor, which delivers a wide potential window of 2 V in a 1 M KCl electrolyte and demonstrates a large energy density of 27.5 mWh cm⁻³ at a high power density of 330 W cm⁻³.