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 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 ₂SO 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.