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

NiV2O6/C composites are prepared via a solid-state conversion process by low temperature (150 °C) annealing nickel‑vanadium-based coordination polymer, [Ni(phen)H2O][V2O6]. The obtained NiV2O6/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 NiV2O6/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 NiV2O6/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 NiV2O6/C nanoribbons possess reversible electrochromism, which is probably related to the intervalence charge transfer (IVCT, VIV → VV).