Tailored charge storage mechanism of a nickel metavanadate/polyaniline composite for high-performance hybrid supercapacitors

Hybrid materials that integrate battery-type and supercapacitive properties hold significant promise for next-generation energy storage systems. In the present work, a strategically designed nickel metavanadate/polyaniline (NVO/PANI) composite is developed to achieve superior energy storage performance. While the pseudocapacitive nature of NVO promotes surface faradaic reactions, integration with PANI lowers the ion-diffusion resistance to leverage the total charge storage. This synergy has been tailored to deliver a high specific capacitance of 1210 F g^-1 at 2 mV s^-1, along with excellent cycling stability, retaining 85.7% coulombic efficiency over 3500 cycles. The distinct charge storage mechanisms of NVO and NVO/PANI have been systematically integrated for the first time to develop a battery-type hybrid supercapacitor that exhibits an impressive specific capacitance of 232 F g^-1 at 4 A g^-1 and a substantial energy density of 22 Wh kg^-1 at an elevated power density of 2.82 kW kg^-1, retaining 100% coulombic efficiency up to 13 000 cycles. With a capacitance that surpasses commercial standards, the NVO/PANI composite represents a breakthrough in energy storage technology. This remarkable advancement provides a cost-effective and scalable strategy to fabricate high-energy, long-life supercapacitors, holding great potential for practical applications in electric vehicles and grid-scale energy storage.