High active mass loading V2O5 electrodes for supercapacitor devices

This investigation addressed the challenges in the fabrication of V2O5 electrodes with high active mass loading, high capacitance, good capacitance retention at high charge-discharge rates and low resistance. High energy ball milling and advanced dispersants, such as tetrahydroxy-1,4-quinone and dihydroxybenzoic acid were used for the particle size reduction, improved particle dispersion and mixing with conductive additives. Ni foams and graphene coated Ni foams were utilized as current collectors for the fabrication of electrodes with high active mass loading. The dispersant concentrations were optimized to maximize electrode capacitance. The highest capacitances of 4.63 and 5.37 F cm-2 (115.8 and 134.4 F g-1) for Ni foam and graphene coated Ni foam current collectors, respectively, were obtained in optimized potential range in the Na2SO4 electrolyte for electrodes with an active mass of 40 mg cm-2. The enhanced performance of graphene coated Ni foam based electrodes was attributed to improved charge transfer. The V2O5 electrodes were used for the fabrication of asymmetric devices for charge storage in a voltage window of 1.6 V, which showed capacitances of 2.45 and 2.73 F cm⁻², and energy densities of 8.9 and 10.9 Wh kg⁻¹ for Ni foam and graphene coated Ni foam current collectors, respectively.