Low temperature synthesis of sponge-like NiV2O6/C composite by calcining Ni-V-based coordination polymer for supercapacitor application

NiV 2 O 6 /C composites are prepared via a solid-state conversion process by low temperature (150 °C) annealing nickel‑vanadium-based coordination polymer , [Ni(phen)H 2 O][V 2 O 6 ]. The obtained NiV 2 O 6 /C nanoribbons are interconnected to form a sponge-like morphology, when the composites are first used as supercapacitor electrode, it exhibits a specific capacitance of 745.6 F g −1 at 0.5 A g −1 with a good rate capability of 520.0 F g −1 (69.7% retention) at 10 A g −1 (20-folds). The NiV 2 O 6 /C composite exhibits good cycling performance, the capacitance retentions at 6000th and 12000th charging/discharging cycles at 2 A g −1 are 81.5% and 77.8% relative to the original capacitances, respectively. The morphological and compositional changes of the NiV 2 O 6 /C composite electrode before and after 12,000 GCD cycles (two-electrode system) are carefully elaborated through a series of characterization (SEM, EDS , and XPS). Furthermore, the NiV 2 O 6 /C nanoribbons possess reversible electrochromism , which is probably related to the intervalence charge transfer (IVCT, V IV  → V V ).