Faculty Publications
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Item Enhancement of supercapacitance of reduced graphene oxide, copper oxide and polyaniline using the mixture of methane sulphonic acid and sulphuric acid as electrolyte(Elsevier Ltd, 2021) Viswanathan, A.; Nityananda Shetty, A.N.The mixture of mineral acid and organic acid as aqueous electrolyte for the rGO12%: Cu2O/CuO40%: PANI48% (G12CP) nanocomposite, exhibited superior energy storage performance. The acid mixture electrolyte used is 0.4 M H2SO4 + 0.4 M CH3SO3H (1:1) (SA + MSA) and it exhibited enhanced diffusion and kinetic features in comparison with the bare 0.4 M H2SO4 (SA) and 0.4 M CH3SO3H (MSA). SA + MSA provided 16.8% higher energy storage than the SA and the performance obtained after 5000 charge/discharge cycles is 276.98% higher than the performance obtained before the cyclic stability test using the same acid mixture electrolyte. The G12CP provided a specific capacitance (Cs) of 490.19 F g?1, an energy density (E) of 98.0392 W h kg--1 and a power density (P) of 1.500l kW kg?1 at 1 A g?1 in the presence of SA + MSA. The obtained E is comparable with E of Li-ion batteries, Ni-metal hydride batteries, Na-S batteries, and Na-metal chloride batteries. © 2020 Elsevier LtdItem Activated carbon- supported Vanado-nickelate (IV) based hybrid materials for energy application(Elsevier Ltd, 2021) Maity, S.; BM, N.; Kella, T.; Shee, D.; Das, P.P.; Mal, S.S.The 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, K2H5[NiV14O40](NiV14), 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-NiV14, 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-NiV14 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 NiV14 composition were studied in acidic aqueous electrolyte (0.5 M H2SO4) solution. We observed that the 15 wt.% of AC-NiV14 hybrid electrode showed remarkable specific energy value (~63.2 Wh kg?1) compared with pristine AC and NiV14 electrodes, separately. Besides, the asymmetric layout (AC//AC-NiV14) 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-NiV14//NiV14 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 LtdItem High-Potential Aqueous Asymmetric Supercapacitor Based on 2D Molybdenum Disulfide and Vanadium Pentoxide Electrodes(American Chemical Society, 2024) Pullanchiyodan, A.; Haridasan, G.T.; Sreeram, P.; Das, A.; T M Balakrishnan, N.; Prasanth, P.; Hegde, A.A wide-operating-voltage asymmetric supercapacitor (ASC) based on an aqueous electrolyte has great promise in the current energy storage technologies by providing better energy density, power density, safety, cost effectiveness, and long cycle life. Herein, the fabrication of an ASC using a 2D transition metal dichalcogenide (molybdenum disulfide (2D MoS2)) and a transition metal oxide (vanadium pentoxide, V2O5) as the negative and positive electrode, respectively, was demonstrated. The electrochemical and galvanostatic charge-discharge analysis of both positive (V2O5) and negative electrodes (2D MoS2) was carried out in a three-electrode setup. The results show stable operating potentials of −0.9 and 1.0 V for MoS2 and V2O5 electrodes, respectively. By combining these positive and negative electrodes in a 1 M sodium sulfate (Na2SO4) aqueous electrolyte, the developed ASC reveals a wide operating potential (2.0 V). The electrochemical analysis of the ASC in a stable operating potential of 1.4 V gives an areal capacitance and energy density of 30 mF/cm2 and 8.2 μWh/cm2, respectively, at a scan rate of 1 mV s-1. The performance of the ASC was analyzed for 5000 continuous charge-discharge cycles at a higher current of 3.5 mA. After 5000 cycles, the ASC exhibits more than 80% capacitance retention with a specific capacitance of 0.85 mF/cm2 © 2024 American Chemical Society.Item Electrochemical performance and structural evolution of spray pyrolyzed Mn3O4 thin films in different aqueous electrolytes: effect of anions and cations(Royal Society of Chemistry, 2024) Adoor, P.; Hegde, S.S.; Badekai Ramachandra, B.R.; George, S.D.; Raviprakash, R.This work presents the impact of cycling in different cationic and anionic aqueous electrolytes on the electrochemical storage performance of the Mn3O4 thin film electrode prepared using the chemical pyrolysis method. Studies on the as-deposited electrode confirmed the formation of Mn3O4 phase. Extensive electrochemical analysis was performed using Na2SO4, NaCl, Li2SO4, K2SO4, and MgSO4 electrolytes to examine the influence of cations and anions on charge storage behaviour. Considerable changes were observed in the specific capacitances owing to different ionic sizes as well as hydrated ionic radius of the electrolyte ions. Accordingly, the electrode unveiled a good performance showing a specific capacitance of around 187 F g−1 at 0.5 A g−1 in K2SO4 electrolyte. Further, the electrode properties are examined after 500 CV cycles to trace the changes in the structural and morphological properties. X-ray diffraction (XRD) and Raman spectroscopic studies illustrate a partial phase transformation of electrodes from Mn3O4 to MnO2 irrespective of the electrolytes. These results are further corroborated with X-ray photoelectron spectroscopic (XPS) analysis where there was an increment in the oxidation state of manganese. It has been observed that the surface properties were significantly changed with cycling, as manifested by the wettability studies of the electrodes. The obtained results brings out the significance of electrolyte ions on the charge storage characteristics of Mn3O4 thin film electrodes in light of their possible application in electrochemical capacitors. © 2024 The Royal Society of Chemistry.