Browsing by Author "Mandal, A."

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Fabrication of 1T VS2 Electrode-Based In-Plane Micro-Supercapacitor Using a Cost-Effective Mask-Assisted Printing Technique
(John Wiley and Sons Inc, 2023) Mandal, A.; Yadav, A.K.; Pandey, S.K.; Chakrabarti, S.
Vanadium disulfide (VS2) is an important member of the transition-metal dichalcogenides (TMDs) family, which offers high conductivity. In nature, it can exist in two phases, i.e., 1T and 2H. Herein, the metallic 1T VS2-based in-plane micro-supercapacitor (MSC) is fabricated by a facile-mask-assisted printing technique. Initially, the 1T VS2 nanosheets are synthesized using a simple one-pot hydrothermal route. The material characterizations have claimed the formation of a 1T phase and the density of states (DOS) reveal that the 1T phase of VS2 is metallic in nature. After experimental and theoretical investigations of synthesized nanosheets, a VS2 electrode-based in-plane MSC is fabricated using a simple mask-assisted printing technique. The fabricated device demonstrates excellent capacitance retention of 97.6% after 1000 cycles of cyclic voltammetry measurement at a 100 mV s−1 scan rate. The device also shows an excellent areal capacitance of 212.7 mF cm−2 and a high areal energy density of 10.63 μWh cm−2 at a high-power density of 4.45 mW cm−2. This low-cost and simple fabrication process can produce high-performance in-plane MSC devices. © 2023 Wiley-VCH GmbH.
Facile hydrothermal synthesis of vanadium disulfide nanomaterial for supercapacitor application
(SPIE, 2023) Mandal, A.; Pandey, N.; Pandey, S.K.; Yadav, A.K.; Chakrabarti, S.
Vanadium disulfide (VS2) is a prominent metallic member of transition metal dichalcogenides (TMDs) family and has already demonstrated its flair in energy storage device applications such as supercapacitors and batteries. In this work, we have synthesized hexagonal shape VS2 nanomaterial using a facile one step hydrothermal route and investigated the phase, morphology and structural properties of the material. The formation of phase has been confirmed from the X-ray diffraction (XRD) plot by correlating with the database of Joint Committee on Powder Diffraction Standards (JCPDS) 00-036-1139 of 1T VS2. Further, the crystalline behavior of VS2 nanomaterial can be seen from the high resolution transmission electron microscopy (HRTEM) measurement. Moreover, the morphology of the synthesized material is obtained from the field emission gun-scanning electron microscopy (FEG-SEM). Also, the characteristic Raman peaks of 1T VS2 at 140.3 cm-1 and 192.3 cm-1 have been observed from the Raman spectrum indicating the metallic behavior of synthesized material. The peak at 281.8 cm-1 is attributed to the in-plane vibrational mode (E2g1) while the peak at 404.5 cm-1 represents the out-of-plane vibrational mode (A1g) of V-S bond. The Fourier transform infrared (FTIR) spectrum shows the V-S-V and V=S vibrational modes around 534 cm-1 and 982 cm-1 respectively. The study introduces a low cost, large scale, highly crystalline, and metallic VS2 nanomaterial with potential application for next generation supercapacitors and other energy storage devices. Â© 2023 SPIE.
Modified Selective Harmonics Mitigation PWM for a Switched Diode Multilevel Inverter
(IOP Publishing Ltd, 2021) Sahaya Ponrekha, A.; Jagabar Sathik, J.; Lakshmanan, P.; Singh, J.; Mani, L.; Mandal, A.; Madhavan, J.
A modified selective harmonic mitigation (SHM) technique for multilevel inverters considering the RMS output voltage magnitude is presented. The harmonic contents in the output voltage of these inverters must satisfy the specified grid code requirement standards. In conventional SHM techniques, the firing angles of the multilevel inverters have been derived by taking into account grid code harmonic reduction standards. When the multi-level inverters are driven with these firing pulses generated, it results in reduction of the magnitude of the inverter output voltage. In order to overcome this issue of output voltage reduction, the modified SHM optimization problem includes another constraint on the RMS output voltage limits, which results in different set of firing angles. This facilitates the use of firing angles, which takes into account the grid code standards of harmonic mitigation without compromising the value of the RMS output voltage of the inverters. The proposal has been simulated and validated in MATLAB Simulink and the experimental results are obtained for a single-phase seven level inverter with Silicon made semiconductor switches. By using the proposed method, output voltage THD (upto 40th harmonics were considered) of 5.9% was obtained, which is well below the harmonic standards specified by EN 50160. © 2021 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.
Synthesis of VS2/N-rGO nanocomposite material for energy storage application
(SPIE, 2023) Mandal, A.; Pandey, S.K.; das Gupta, K.; Chakrabarti, S.
Vanadium disulfide (VS2), which belongs to transition metal dichalcogenides (TMDs) group, is a prominent material for energy storage application. On the other hand, graphene like carbon-based nanomaterials offer improved electrochemical performance due to high specific surface area, excellent conductivity, good chemical, and mechanical stability. Therefore, composite of graphene like material with TMD have shown better electrochemical performance till date. In this work, we have synthesized VS2/N-rGO composite material, which can be applicable for energy storage device. At first, we have synthesized graphene oxide (GO) using Tour method. Then we reduced GO along with nitrogen doping using hydrothermal route. After that, we have synthesized VS2/N-rGO by hydrothermal method. The X-ray diffraction (XRD) spectrum of GO shows a prominent peak at 10.2Â°, which implies the interlayer spacing in GO of 8.7 Ã…. After reduction and doping with nitrogen (N), two peaks are obtained at 24.7Â° (d=3.6 Ã…), and 42.3Â° (d=2.1 Ã…) in the XRD pattern which corresponds to N-rGO. RAMAN spectrum of composite shows the characteristics peaks of VS2 at 141.6, 194.5, 286.4, 404.1, 680.1 and 997.2 cm-1 along with D and G bands coming from the N-rGO. We have also performed the Fourier-transform infrared-spectroscopy (FTIR) and Field-emission gun-scanning electron-microscopy (FEG-SEM) characterizations to investigate the bonding vibration and surface morphology of the materials. The synthesized material is suitable for energy storage applications. Â© 2023 SPIE.