Abstract
Intercalation pseudocapacitance is of essential significance for designing high performance electrode materials, which offers exceptional charge storage characteristics. In this study, we elucidate the pseudocapacitive behavior of Al3+ ions intercalation within the distinctive tunnels of monoclinic W18O49 nanostructure. 3D sea urchin-like W18O49 is synthesized through one-step solvothermal approach. Its physicochemical properties are investigated by X-ray diffraction, X-ray photoelectron spectroscopy, Field emission scanning electron microscopy and Brunauer-Emmett-Teller surface area analysis. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques are used to investigate the electrochemical characteristics of W18O49 electrode in different electrolyte systems. It shows high specific capacitance of 350 F g−1 at 1 A g−1, superior electrochemical long-term stability in the Al3+ electrolyte with 92% capacitance retention at 8000 cycles. The excellent electrochemical performance is predominantly due to the Al3+ ions intercalation/de-intercalation with W18O49 nanostructure that is proven by ex situ X-ray diffraction analysis. The work marks a notable achievement in the effort of substituting commonly acidic proton electrolyte for W18O49 supercapacitor.
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•A 3D sea urchin-like W18O49 nanostructure is prepared by solvothermal route.•W18O49 shows high capacitance in Al3+ electrolyte due to ions intercalation.•Al3+ ions intercalate/de-intercalate to cause lattice contraction/expansion.•Al3+ electrolyte as substitute for corrosive acidic electrolyte for W18O49.