Maity, S.BM, N.Kella, T.Shee, D.Das, P.P.Mal, S.S.2026-02-052021Journal of Energy Storage, 2021, 40, , pp. -https://doi.org/10.1016/j.est.2021.102727https://idr.nitk.ac.in/handle/123456789/23146The rapid development of supercapacitor (SC) technology leads to increased demand for nanofabrication of novel and effective electroactive hybrid materials for next-generation energy storage devices. Herein, nickel tetradecavanadate, K<inf>2</inf>H<inf>5</inf>[NiV<inf>14</inf>O<inf>40</inf>](NiV<inf>14</inf>), is doped into porous activated carbon (AC), for the first time, in different wt.% in order to investigate the homogeneous loading of the inorganic metal-oxide component on the AC matrix. The resulting complex, AC-NiV<inf>14</inf>, is found to have possessed an enhanced electrochemical characteristic (for both symmetric and asymmetric SC cell), which operates at a significantly higher potential of 1.2 V. The combination of the double-layer capacitance (EDLC) and the redox-active polyoxometalate cluster leads to an intrinsic increase in specific capacitance (capacity) (from 45.3 Fg?1 (54.4 Cg?1) for AC to 316 Fg?1 (379.2 Cg?1) for 15 wt.% AC-NiV<inf>14</inf> at a current density of 1 Ag?1). It was also observed that there is an increase of 20% in the operating voltage compared to conventional AC supercapacitors with acidic aqueous electrolytes. Firstly, symmetric supercapacitor's electrochemical performances of various wt.% of NiV<inf>14</inf> composition were studied in acidic aqueous electrolyte (0.5 M H<inf>2</inf>SO<inf>4</inf>) solution. We observed that the 15 wt.% of AC-NiV<inf>14</inf> hybrid electrode showed remarkable specific energy value (~63.2 Wh kg?1) compared with pristine AC and NiV<inf>14</inf> electrodes, separately. Besides, the asymmetric layout (AC//AC-NiV<inf>14</inf>) increased the potential window up to 1.5 V and enhanced the specific energy and power values (90.1 Whkg?1 and 2400 Wkg?1, respectively), with 98% coulombic efficiency. Meanwhile, the AC-NiV<inf>14</inf>//NiV<inf>14</inf> asymmetric cell possesses a specific capacitance (capacity) of 375 Fg?1 (450 Cg?1) with a maximum power of 3140 Wkg?1 at the high current density of 2 Ag?1. © 2021 Elsevier LtdActivated carbonCapacitanceElectrodesElectrolytesElectrolytic capacitorsHybrid materialsMetalsOxidesRedox reactionsActivated carbon supportedAg$++$Aqueous electrolyteAsymmetricHybrid electrodesHybrids materialPolyoxometalatesSpecific capacitanceSpecific energySymmetricsSupercapacitor