Large-area multifunctional electro-chromic-chemical device made of W17O47 nanowires by Zn2+ ion intercalation

Abstract Both electrochromic and electrochemical processes have been widely investigated separately for respective energy saving and storage technologies. It would be of considerably value to effectively integrate the dual functionalities into a single multifunctional electro-chromic-chemical device (MED) capable of both. Herein, having considered the well theoretical capacity (820 mAh g−1), cost-effectiveness and high safety, we report the successful fabrication of MED in large area made of W17O47 nanowires, where Zn2+ ion intercalation takes place in the oxygen-vacant monoclinic tungsten oxide with WO polyhedral. The MED electrode materials demonstrate excellent cycling stability, large optical modulation (∆T) and high capacitance, when the polyhedron-enclosed interstitial sites form tunnels that facilitate Zn2+ ion diffusion, yielding a high specific capacitance (353.8 F g−1 at 0.5 A g−1) and a quite large optical modulation (∆T = 83.2% at 633 nm). With NaWO3 as a minor phase together with W17O47 nanowires, our density functional theory (DFT) calculations reveal a robust W17O47/NaWO3 interface structure, which leads to a desirable cycling stability (still maintaining 74.3% of its original optical modulation after 4000 cycles). The large-area MEDs assembled with W17O47/NaWO3 electrodes exhibit excellent energy-saving and energy-storage properties. For example, the temperature of an inner room equipped with the MED (30.5 cm × 26 cm) is 18.3 °C lower than that of a room equipped with blank glass, suggesting that the amount of irradiation is shielded significantly. Two series-connected MEDs (each size: 15 cm × 10 cm) is demonstrated to light up 4 light-emitting diodes (LEDs, 1.8–2.6 V) for more than 35 min