Guiding nitrogen doped vanadium pentoxide nanoclusters on cobalt sulfide nano-flakiness as stable seamless interface anode toward highly energy density and durable asymmetric supercapacitors.

Interaction of the interface-heterostructures is crucial to rapid ionic conductivity and highly energy density of electrode materials toward supercapacitors. Herein, a novel anode heterostructure is synthesized using cobalt sulfide (CoS) nanoflowers as a substrate for composite nitrogen doped vanadium pentoxide (denoted as N-VO@CoS) by combination of hydrothermal and calcination method. As expected, the N-VO@CoS electrode possesses superhigh specific surface area that significantly enhances the specific capacitance, and its unique porous interconnected structure not only reduces the volume effect during the cycles, but also greatly enhances the conductivity of electron transfer. The as-prepared N-VO@CoS electrode has a specific capacitance of up to 2413.6F/g at a current density of 1 A/g, and can still maintain 87.51 % of the initial capacitance after 5,000 cycles at a high current density of 10 A/g. More importantly, the partial density of states (PDOS) ares obtained through theoretical calculations reveal that the interaction of heterogeneous interfaces is contributed by the p-orbitals of C, O and S and d-orbitals of V and Co. In addition, asymmetric supercapacitor (ASC) with N-VO@CoS as the positive electrode and activated carbon (AC) as the negative electrode has a high voltage of 1.7 V, which achieves an outstanding energy density of 71.6 W h kg at a power density of 849.8 W kg, showing excellent cycle stability (retain 90.6 % of the initial capacitance after 10,000 charge/discharge cycles). This paper offers novel paradigm for the doping of metal oxides and the development of heterostructures, which provides support for their use as advanced energy storage materials.