Faculty Publications

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    Ionic Liquid Electrolytes for Flexible Supercapacitors
    (wiley, 2021) Udaya Bhat, K.; Bhat Panemangalore, D.B.
    Compact, flexible, high energy and high density energy storage devices are required to power electronic skins, implantable devices and flexible sensors. Compact and flexible supercapacitors are the need of the hour. Research has been in progress to improve the performance of the electrodes and electrolyte with respect to the batteries and supercapacitors. A number of electrolytes have been designed and tested for the supercapacitor applications. Electrolytes based on ionic liquids are useful to improve the performance from the angle of widening operating voltage, improving energy density, charge-discharge cycling, etc. In this chapter, essential details of a supercapacitor, followed by different components of a supercapacitor, various types and features of electrolytes, developments in ionic liquid electrolytes, design aspects in ionic liquid electrolyte usage, concept of mechanical integrity in flexible supercapacitor design are explored. © 2021 Scrivener Publishing LLC.
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    Organic-inorganic hybrid mixed-valent bisphosphonate-polyoxovanadates composites with activated carbon for energy storage applications
    (Nova Science Publishers, Inc., 2024) Madhusree, J.E.; Banerjee, A.; Mal, S.S.
    In this book, we discuss the investigation of two different bisphosphonate-functionalized polyoxovanadate compounds for use in electrochemical energy storage applications. The compounds are (NH4)4[H6(VIVO2)(VV2O5)2O3P-C(O)(CH2-2-C5NH4)-PO32].9H2O (m), and (NH4)4[H6(VIVO2)(VV2O5)2O3P-C(O)(CH2-3-C5NH4)-PO32]. 8H2O (n). They have a mixed-valent oxovanadate polyanionic assembly that has two different pyridyl functional groups present on the organic bisphosphonate ligand. Several techniques have been used to characterize composites made from these compounds with activated carbon, including Fourier transform infrared spectroscopy, P-XRD, FESEM, EDX, and surface adsorption-desorption tests. The electrochemical performance of acidic electrolytic solutions containing 0.1 M H2SO4, AC-m, and AC-n electrode materials was investigated. Although the compounds are isotypic mixed-valence polyoxovanadate structures, their electrical behavior varies based on the position of the pyridyl group. AC-n was reported to have the most prominent specific capacitance of 313 F g-1 at a current density of 1 A g-1 in a voltage window of 0-1 V, with exceptional energy and power densities of 43.56 Wh kg-1 and 1999.72 W kg-1, respectively. At the same time, AC-m exhibited a specific capacitance of 212 F g-1 and a specific energy of 29.45 Wh kg-1. By lighting up different LED lights with only 42 mg of carbon clothcoated sample, the composite AC-n electrode displayed exceptional specific power. A further benefit of AC-n nanohybrids is their ability to retain electrochemical performance over time, which suggests long-term stability. © 2024 Nova Science Publishers, Inc. All rights reserved.
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    Electrochemical comparison of nickel and nickel hydroxide nanoparticles composited with reduced graphene oxide and polyaniline for their supercapacitor application
    (American Institute of Physics Inc. subs@aip.org, 2018) Viswanathan, A.; Nityananda Shetty, A.
    The reduced graphene oxide/polyaniline/Ni(OH)2 (GP-Ni(OH)2) and reduced graphene oxide/polyaniline/Ni (GP-Ni) nanocomposites were synthesized by facile in situ single step chemical method. The constituents were confirmed by powder-XRD, and the electrochemical characterizations were carried out using cyclic voltammetry(CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The electrochemical contribution of Ni(OH)2 and Ni to their supercapacitance along with reduced graphene oxide and polyaniline was compared. The GP-Ni nanocomposite exhibited a specific capacitance of 266.66 F g-1, energy density of 53.33 W h kg-1 and power density of 1385 W kg-1 at a current density of 0.25 A g-1 and the results were enhanced to 21% and more promising than that of nanocomposite GP-Ni(OH)2. © 2018 Author(s).
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    Amelioration of supercapacitance of mixed metal oxide dispersed reduced graphene oxide and polyaniline nanocomposites using Ch3SO3H as supporting electrolyte in H2SO4
    (Elsevier Ltd, 2019) Viswanathan, A.; Nityananda Shetty, A.
    Reduced graphene oxide/polyaniline/ Cu2O-SnO2 (5:2) nanocomposite was synthesised by facile in-situ one step chemical method. Its composition and structural morphology were characterized using powder-XRD, energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM). The capacitive performances were evaluated using cyclic voltammetry (CV), galvanostatic charge – discharge(GCD), and electrochemical impedance spectroscopy (EIS) with 0.4 M H2SO4 and a mixture of 0.4 M H2SO4 and 0.4 M CH3SO3H (1:1) as electrolytes. The amelioration of electrochemical parameters was observed in the mixture of electrolytes. The specific capacitance of 230.41 F g–1, energy density of 46.08 W h kg–1, and power density of 1530.39 W kg–1 were obtained. The enhancement of the electrochemical properties was found to be about 20 % with the mixture of 0.4 M H2SO4 and 0.4 M CH3SO3H (1:1) over bare 0.4 M H2SO4. © 2019 Elsevier Ltd. All rights reserved.
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    Binder free MoO3/multiwalled carbon nanotube thin film electrode for high energy density supercapacitors
    (2013) Aravinda, L.S.; Bhat, K.; Badekai Ramachandra, B.
    MoO3/multiwalled carbon nanotube (MWCNT) composites were prepared by Magnetron sputtering in Ar/O2 atmosphere. This will provide a greener alternative for the fabrication of binder free composite electrode for supercapacitor applications. MWCNT provides good support for the growth of MoO3 thin films. This integrated composite electrode exhibited specific capacitance of 93 F g-1 and a corresponding energy density of 7.28 Wh kg-1 in non-aqueous electrolyte, which is almost fourfold increase compared to the bare MWCNT. Also the electrode maintains high power density of 4930 W kg-1 at high current rates, suggesting a potential energy storage material for portable and consumer electronics. © 2013 Elsevier Ltd. All rights reserved.
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    Single step synthesis of rGO, copper oxide and polyaniline nanocomposites for high energy supercapacitors
    (Elsevier Ltd, 2018) Viswanathan, A.; Nityananda Shetty, A.N.
    Reduced graphene oxide, copper oxide and polyaniline (GCP) nanocomposites possessing energy densities close to many of Li-ion batteries are synthesized by facile in-situ single step chemical method by varying the weight percentage of each of the constituent materials. Of all the composites synthesized, the one with weight percentage of G12%: Cu2O/CuO40%: P48% (G12CP) exhibits the maximum specific capacitance of 684.93 F g?1, specific capacity of 821.91 C g?1, energy density of 136.98 W h kg?1, and power density of 1315.76 W kg?1 at the current density of 0.25 A g?1. The composite shows the retention of 84% of its initial capacitance up to 5000 cycles at a scan rate of 700 mV s?1. The electrochemical performance of G12CP is superior to the performances of other ternary composites and those of binary composites synthesized with respective weight ratios as that of G12CP composite. The potential of G12CP to act as a secondary power backup device is successfully demonstrated and the performance obtained is comparable with some of the previously reported similar works, and even superior to some others. © 2018 Elsevier Ltd
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    Facile solvothermal synthesis and high supercapacitor performance of NiCo2O4 nanorods
    (Elsevier Ltd, 2019) Sethi, M.; Bhat, D.K.
    NiCo2O4 nanorod arrays were synthesized employing a facile low-temperature solvothermal approach, followed by post-calcination treatment. The structural, morphological and elemental characterizations were done by diffraction, microscopic and spectroscopic techniques. The prepared sample was studied as an active electrode material for supercapacitor application in 2 M KOH aqueous electrolyte. The cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectral (EIS) studies were carried out to know the electrochemical activity of the prepared material. From the CV study, a high capacitance value of 440 F g?1 was obtained at a scan rate of 5 mV s?1 in a 3-electrode method. Apart from high capacitance value, the prepared electrode depicted 94% initial capacitance retention value after 2000 charge-discharge cycles at a current density of 8 A g?1. The fabricated symmetrical supercapacitor depicted a high energy density of 12.6 Wh kg?1 and a high power density of 4003 W kg?1. This was attributed to the better electrical conductivity of NiCo2O4 nanorods. © 2018 Elsevier B.V.
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    High energy reduced graphene oxide/vanadium Pentoxide/polyaniline hybrid supercapacitor for power backup and switched capacitor converters
    (Academic Press Inc. apjcs@harcourt.com, 2019) Viswanathan, A.; Prakashaiah, B.G.; Subburaj, V.; Nityananda Shetty, A.N.
    The robust reduced graphene oxide (rGO)/vanadium pentoxide (V 2 O 5) /polyaniline (PANI) nanocomposite with a weight percentage of rGO – 5.88%: V 2 O 5 – 11.76%: PANI – 82.36%, was synthesized by facile insitu single step chemical method and fabricated into a supercapacitor device. The supercapacitor exhibited high energy density of 54.62 W h kg ?1 and an exceptionally high sustainability of its performance up to 13,000 rechargeable cycles at high charge/discharge rate. The high energy density was further confirmed when the supercapacitor containing the afore mentioned composite, acted as an excellent secondary power source to store and deliver energy for substantially long time when charged at an exceptionally high current using a commercial 9 V battery. Further, its energy storage and delivery capabilities were established by using it in a real time switched capacitor converter circuit and the obtained performance for potential step up and step-down purposes were gratifying. The obtained electrochemical parameters included a maximum specific capacitance of 273F g ?1 specific capacity of 327.6C g ?1 , energy density of 54.62 W h kg ?1 and a power density of 1636.5 W kg ?1 at a current density of 1 A g ?1 . © 2019 Elsevier Inc.
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    Real time magnetic supercapacitor with antiferromagnetic nickel hydroxide based nanocomposite
    (Elsevier Ltd, 2019) Viswanathan, A.; Nityananda Shetty, A.N.
    An antiferromagnetic, semiconducting nickel hydroxide (Ni(OH) 2 ), with a good theoretical capacitance is composited with reduced graphene oxide and polyaniline to synthesize the electrode material for energy storage in supercapacitors. The composite overcomes the limitation of low conductivity of nickel hydroxide. The conductivity and antiferromagnetic nature of nickel hydroxide are altered by applying magnetic field, which in turn enhances its energy storing capacity. A ternary composite with the weight percentages of 4%: 48%: 48% of reduced graphene oxide/nickel hydroxide/polyaniline (GN48P), respectively, exhibits a magnetic susceptibility of 850. The application of a magnetic field of 625 ?T results in an enhancement of performance of the composite, exhibiting a specific capacitance of 19.14 F g ?1 , specific capacity of 22.97 C g ?1 , energy density of 0.6649 W h kg ?1 , a power density of 17.57 W kg ?1 at a current density of 0.25 A g ?1 and retention of 85.19% of its original capacitance up to 5000 cycles. This premier study on the effect of magnetic field, on the electrochemical performance of the supercapacitor in a typical two electrode system showed 69.4% increase in its specific capacitance. © 2019 Elsevier Ltd
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    High power density and improved H2 evolution reaction on MoO3/Activated carbon composite
    (Elsevier Ltd, 2020) Sangeetha, D.N.; Holla, R.S.; Badekai Ramachandra, B.; Muthu, M.
    The formation of hexagonal MoO3 (h- MoO3) microrods was favoured at lower pH in the hydrothermal synthesis method. Symmetric and Hybrid supercapacitors were fabricated using h-MoO3/plastic bottle derived activated carbon (PAC) composite in 1 M Na2SO4 aqueous electrolyte. The operating voltage for the aqueous electrolyte was maximized to 1.6 V with this combination. The wide operating voltage led to a maximum specific capacitance of 211 Fg-1, power density of 287 W kg?1 and 79% efficiency even at 5000 charge-discharge cycles for the hybrid supercapacitor combination. The combined effect of PAC micropores along with the 1-D rod-shaped h-MoO3, helped in faster charge-transfer, hence increasing the efficiency of supercapacitors. Further, the composites of defective PAC (PDAC) together with the h-MoO3 when tested for hydrogen evolution reactions (HER), provided lesser onset potential and Tafel slope values of ?0.23 mV and ?93 mVdec?1. There was a change in the structural environment of carbon due to the heteroatom doping and dedoping producing defects in PAC, termed as PDAC. These defects together with the hexagonal microrods of MoO3 provided fast electron transfer towards hydrogen adsorption/desorption hence effectively producing H2. © 2019 Hydrogen Energy Publications LLC