Enhanced van-der Waals separation in hydrated tungsten oxide nanoplates enables superior pseudocapacitive charge storage

Abstract

Engineering the van-der-Waals gap by interlayer water confinement and hydration enable superfast ions transfer and intercalation that boosts the charge storage performance. Herein, we report the van-der-Waals gap modification into the layered WO 3 nanostructures using cost-effective wet chemical method. The larger water molecules insertion into the hydrated WO 3 crystal structure facilitates the expansion of van-der-Waals gap, which results the improvement of nanoplates thickness. The electrochemical performance in the thicker hydrated WO 3 nanoplates is enhanced owing to the better crystalline nature and electrical conductivity along with van-der-Waals gap modification. Hence, the significant boost of single electrode specific capacitance from 160 F g −1 to 250 F g −1 at 2 mV s −1 is observed in 1 M H 2 SO 4 aqueous electrolyte. Further an asymmetric supercapacitor of 1.6 V exhibits the capacitance value 27 F g −1 at 1 A g −1 with 8000 Wh kg −1 power density and 87% capacitance retention after 2500 cycles. The van-der-Waal gaps engineering of layered materials is a potential strategy to amplify supercapacitor performance. • The increasing crystallinity, and thickness of layered WO3. H2O sheets into 3D nanoplates by enhancing van der Waals gap. • The higher specific capacitance 250 F g-1 of thicker sample is observed than other nanoplates (160 F g-1) at 2mV s -1 . • The nanoplates demonstrates the excellence capacitance retention of 87% after 2500 cycles. • Confined hydrate into the layer enhance surface area and improve proton insertion via Eigen-Zundel-Eigen mechanism.