High-rate quasi-solid-state hybrid supercapacitor of hierarchical flowers of hydrated tungsten oxide nanosheets

Morphology modification and crystal structure engineering of electrode materials play a significant role in their electrochemical storage performance. We report a single step, room temperature preparation of self-assembled hierarchical flowers of hydrated WO3 nanosheets by a wet-chemical method for quasi-solid-state hybrid supercapacitor. The nanosheets exhibit the single crystalline-layered structure separated by confining water molecules auspicious for intercalation and proton conduction mutually. The excellent capacitance 457 Fg−1 at a low scan-rate of 2 mVs−1 is prominently achieved owing to the intercalated pseudocapacitance through vital proton diffusion into the electrode. Further, the temperature-dependent electrochemical analysis implies the robust, sustainable feature of hierarchical WO3 flowers. A quasi-solid-state hybrid supercapacitor of WO3//reduced graphene oxide (rGO) demonstrates a large total working voltage of 1.6 V, ensuring the high energy density of 31 WhKg−1. Thus the structural and morphological engineering of the tungsten oxide anode has emphasized a great potential of proton insertions that revolutionize the electrochemical storage technology. © 2020 Elsevier Ltd