Starfruit-Like Vanadium Oxide with Co2+ Pre-Intercalation and Amorphous Carbon Confinement as a Superior Cathode for Supercapacitors

The vanadium dioxide (VO2(D)), with ultra-high theoretical capacitance, has been considered as a boon for electrode materials of advanced supercapacitors (SCs). However, the VO2 has a series of shortcomings such as poor electrical conductivity, severe structural damage, and rapid capacity fading during repetitive cycles, resulting in non-ideal electrochemical performance. Herein, the Co2+ pre-intercalation and amorphous carbon confined vanadium dioxide (CoxVO2@C) is synthesized on a conductive Ni foam substrate via a versatile and cost-effective method as a high-performance cathode for SCs. The obtained starfruit-like nanostructure not only enables a small amount of Co2+ pre-intercalation layer to offer faster ion diffusion kinetics for VO2, but also utilizes a high-conductivity amorphous carbon confinement to protect VO2 from dissolution in an alkaline electrolyte, thereby exhibiting the ultrahigh specific capacitance up to 4440.0 mF cm-2 at 5 mA cm-2 (525.2 F g-1 at 2 A g-1) and the prominent long-term stability performance of the electrode. Benefited from these excellent characteristics, a high-performance CoxVO2@C//V2O3 hybrid supercapacitor device with an operating voltage of 1.7 V is further assembled. The HSC device delivers a superior energy density of 102.3 W h kg-1at a power density of 6.1 kW kg-1, manifesting its practical feasibility. Therefore, these ingenious structural designs may contribute to the development and application of vanadium-based materials in the future