Unveiling the redox electrochemistry of 1D, urchin-like vanadium sulfide electrodes for high-performance hybrid supercapacitors

Exploring novel versatile electrode materials with outstanding electrochemical performance is the key to the development of advanced energy conversion and storage devices. In this work, we aim to construct new-fangled one-dimensional(1D) quasi-layered patronite vanadium tetrasulfide(VS4) nanostructures by using different sulfur sources, namely thiourea, thioacetamide, and L-cysteine through an ethyleneaminetetraacetic-acid(EDTA)-mediated solvothermal process. The as-prepared VS4exhibits several unique morphologies such as urchin, fluffy nanoflower, and polyhedron with appropriate surface areas. Among the prepared nanostructures, the VS4-1@NF nanostructure exhibited excellent electrochemical properties in 6 M KOH solution, and we explored its redox electrochemistry in detail. The asprepared VS4-1@NF electrode exhibited battery-type redox characteristics with the highest capacity of280 C g-1in a three-electrode assembly. Moreover, it offered a capacity of 123 F g-1in a hybrid twoelectrode set-up at 1 A g-1with the highest specific energy and specific power of 38.5 W h kg-1and750 W kg-1, respectively. Furthermore, to ensure the practical applicability and real-world performance of the prepared hybrid AC@NF//VS4-1@NF cell, we performed a cycling stability test with more than 5,000galvanostatic charge–discharge cycles at 2 A g-1, and the cell retained around 84.7% of its capacitance even after 5,000 cycles with a CE of 96.1%.