Synergistic effects of haematite/hausmannite anchored graphene hybrids in high-energy density asymmetric supercapacitors

Abstract

Addressing the critical demand for advanced energy storage systems (ESSs) amid escalating global energy needs and population growth, this study pioneers the synthesis of graphene-supported haematite and hausmannite (Gr@Mn3O4@Fe2O3/NF) ternary composite cathodes. These cathodes are tailored for high-performance asymmetric supercapacitors (ASCs), leveraging an economically viable process of fabrication. This innovation represents a significant leap forward, employing cost-effective techniques without compromising efficiency. Synchrotron X-ray absorption spectroscopy (XAS) analysis reveals a distinct blend of Fe and Mn valences, confirming the composite's unique structure. Electrochemical assessment underscores the superior capability of the electrodes, registering an unprecedented specific capacitance of ∼854 F/g in aqueous electrolytes, far surpassing traditional electrodes. Additionally, the composite electrodes maintain ∼70 % capacitance retention and about ∼94 % coulombic efficiency under a high current density of 4 A/g. In an ASC configuration, pairing the Gr@Mn3O4@Fe2O3/NF cathode with an anode made of AC, the ASC achieves the highest capacitance of ∼139 F/g, an energy density of ∼156.3 Wh/kg at a power density of ∼1439 W/kg, coupled with outstanding cyclability in a 1.5 V. This research delineates a scalable pathway for fabricating cost-efficient, high-energy density SCs, heralding a new era of portable electronic devices with enhanced energy storage capabilities.