Faculty Publications
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Item Effect of dopants on the energy storage performance of reduced graphene oxide/polyaniline nanocomposite(Elsevier Ltd, 2019) Viswanathan, A.; Nityananda Shetty, A.N.The nanocomposites comprising of reduced graphene oxide (rGO) and polyaniline (PANI) were synthesized by facile insitu single step chemical methods, with glacial acetic acid (AA) and methane sulphonic acid (MSA) as dopants for PANI. The rGO/PANI nanocomposites synthesized with the similar weight percentages of constituents exhibited better electrochemical performance in the presence of MSA than in the presence of AA, in the real two-electrode supercapacitor cell system. The nanocomposite of weight percentages of rGO-6.7%, and PANI-93.33% (GP93MSA), with MSA as dopant exhibited a remarkable feature of increase in energy storage when the number of cycles was increased. It exhibited a maximum enhancement of 237.44% in its energy storage performance, after 13600 cycles as compared to the performance before the onset of cyclic test. The high performances obtained with GP93MSA include high specific capacitance of 512.82 F g?1, specific capacity of 615.38 C g?1, energy density of 102.56 W h kg?1 and a power density of 1.8954 kW kg?1 at 1 A g?1. The energy density of the supercapacitor with GP93MSA as the electrode material, is of the same order as that of Li-ion batteries. Also, GP93MSA showcased good cyclic stability up to 23000 cycles. © 2019 Elsevier LtdItem Superior supercapacitance exhibited by acid insoluble Ni(OH)2 in the form of its nanocomposite with rGO(Elsevier Ltd, 2022) Viswanathan, A.; Acharya, M.G.; Prakashaiaha, B.G.; Nityananda Shetty, A.N.The solubility of Ni(OH)2 in acids was been the major impediment that has been preventing the usage of acid electrolytes like 1 M H2SO4 in supercapacitors and batteries that contain Ni(OH)2 as electrode material. This impediment is successfully removed and impressive energy storage characters were achieved from an electrode made up of Ni(OH)2 in the presence of acid electrolyte of 1 M H2SO4. This acid insoluble form of Ni(OH)2 was achieved by synthesizing it in situ in the presence of graphene oxide by chemical reduction method to produce the stable nanocomposite of reduced graphene oxide (rGO) and Ni(OH)2. The insolubility of Ni(OH)2 in 1 M H2SO4 was carefully studied for nearly six months and proved to be a factual observation. Remarkably, the rGO/Ni(OH)2 composite exhibited the better energy storage performance in the presence of 1 M H2SO4 in relation with conventional methods that involve basic electrolytes like NaOH and KOH for Ni(OH)2. The supercapacitor containing rGO/Ni(OH)2 composite and 1 M H2SO4, was stable in storing and delivering the energy without deterioration up to 31,500 cycles, with an uniqueness of increase in energy storage with increase in cycles of energy storage and delivery. Remarkably, two type of faradaic processes are observed to be contributing to the total energy storage of Ni(OH)2, of which one is unprecedented. The superior specific energy (E) and specific capacitance (Cs) achieved are 130.7175 W h kg−1 (comparable with Li-ion batteries of 3 V) and 653.5947 F g−1 at 1 A g−1. This superior Cs is higher than the theoretical Cs expected from this composite for this specific composition (rGO33.33 % and Ni(OH)2 66.66 %) (1571 F g−1) and higher than the theoretical Cs of Ni(OH)2 (2082 F g−1). It is expected that this study would be an inevitable attraction and take the applicability of Ni(OH)2 to higher level and make it one of the meritorious materials for future energy storage. © 2022 Elsevier LtdItem Durable and high energy yielding PANI/Ni(OH)2 nanocomposites and its supporting electrolyte improved supercapacitance(Elsevier Ltd, 2024) Viswanathan, A.; Nityananda Shetty, A.N.The driving force behind supercapacitor research is to enhance the energy density (E) to the level of Li-ion batteries, and achieving high power density (P). This task is accomplished by using nanocomposites of polyaniline (PANI) and Ni(OH)2 (PN) as the electrode material for supercapacitors. These nanocomposites were synthesized using acetic acid (PN - AA) (PANI 75% and Ni(OH)2 25%) and methane sulphonic acid (PN - MSA) (PANI 83.33% and Ni(OH)2 16.67%) as dopants for PANI through an in-situ single-step method. The PN – MSA exhibited higher energy storage characters than PN – AA with 1 M H2SO4 (SA) as electrolyte. PN - MSA exhibited high-energy characteristics, including a specific capacitance (Cs) of 735.29 F g‒1, an energy density (E) of 147.05 W h kg‒1 (comparable to Li-ion batteries), and a power density (P) of 2.3466 kW kg‒1 at 1 A g‒1. In addition, it also exhibited an exceptional cyclic stability up to 58,800 cycles at 0.4 V s‒1. The energy characters of PN-AA are also substantially high and are a Cs of 641.02 F g‒1, an E of 128.20 W h kg‒1 (in the same order of Li-ion batteries), a P of 2.0385 kW kg‒1 at 1 A g‒1 and a cyclic stability up to 18,400 cycles was also obtained at 0.4 V s‒1. Both PN - AA and PN - MSA demonstrated an impressive feature of an increase in energy storage with an increase in the number of charge/discharge cycles. PN - MSA exhibited an improvement in energy storage characteristics of up to 44% when a mixture of sulphuric acid and methane sulphonic acid with concentrations of 1 M and 0.33 M, respectively, was used as an electrolyte. © 2024 Elsevier Ltd