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

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 WO3 nanostructures using cost-effective wet chemical method. The larger water molecules insertion into the hydrated WO3 crystal structure facilitates the expansion of van-der-Waals gap, which results the improvement of nanoplates thickness. The electrochemical performance in the thicker hydrated WO3 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 H2SO4 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.