Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
19 results
Search Results
Item Comparative Studies on Crystalline and Amorphous Vinylidene Fluoride Based Fibrous Polymer Electrolytes for Sodium-Ion Batteries(Springer Singapore, 2020) Janakiraman, S.; Khalifa, M.; Biswal, R.; Ghosh, S.; Anandhan, S.; Adyam, A.In the present work, electrospun poly (vinylidene fluoride) (PVDF) and poly (vinylidene fluoride-co hexafluropropylene) (P(VdF-co-HFP)) fibrous membranes have been compared. Porous homo and copolymer fiber-based membranes with an interconnected structure, high porosity, large electrolyte uptake were prepared by an electrospinning route. The effect of crystallinity in terms of X-ray diffraction (XRD) was investigated for the fibrous polymer membranes (FPMs). The surface morphology of the FPMs is evaluated by field emission scanning electronmicroscopy (FESEM). The FPMswere soaked in 1MNaClO4-ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1, vol%) solution to form fibrous polymer electrolytes (FPEs). The ionic conductivity of copolymer showed 1.126 mS cm−1 under ambient temperature (at 28 °C) higher than the homopolymer (0.79 mS cm−1) because of HFP unit. The electrochemical stability window of the copolymer membrane also enhanced and stable up to 4.9 V versus Na+/Na suitable for high voltage sodium rechargeable batteries. When tested with Na066Fe0.5Mn05O2 as cathode and Na metal as an anode, the cycle performance significantly improved for the copolymer. © Springer Nature Singapore Pte Ltd. 2021.Item Implementation of Acoustic Emission Testing to Study the Type of Cracking in Reinforced Concrete Beams(Springer Science and Business Media Deutschland GmbH, 2021) Ghosh, S.; Agrawal, R.; Vidya Sagar, R.In this experimental study, crack classification in reinforced concrete (RC) beams was carried out using acoustic emission (AE) testing. Two types of under reinforced RC beams were tested in laboratory subjected to four-point bending, and monotonically increased load was applied. The first type of RC beam had shear reinforcement (steel stirrups), and the second type of RC beam had no shear reinforcement. The generated AE during the fracture process in the tested RC beams were used for the crack classification analysis. Gaussian mixture modeling (GMM) of acoustic emission signals was performed. It was observed that the RC beam without shear reinforcement failed suddenly (brittle nature). However, the RC beam with shear reinforcement failed gradually thereby exhibiting ductile nature. In both the RC beams, considerable AE related to shear cracking appeared at a 20–30% peak load. In the case of the RC beam with shear reinforcement, initially, tensile cracks were developed at the bottom of the beam and slowly started widening upward. Diagonal shear cracks started forming near to the supports when the test specimen reaching to collapse. In the case of the RC beam with no shear stirrups, tensile cracks originated at the bottom of the beam. But in this case, the influence of shear cracks developed near to the supports was more pronounced as it propagated rapidly. By comparing the different AE parameters, a steady increase in the number of hits till failure was observed in the case of the RC beam with shear reinforcement. But on the other hand, an abrupt increase in the number of hits was observed after 50% of peak load in the case of the RC beam with no shear reinforcement. The results are useful to study the sensitivity of AE to the shear reinforcement present in the RC beams. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item A Novel Orbirect Inductive Coil Structure for Wireless Inductive Power Transfer in Electric Vehicle Battery Charging Applications(IEEE Computer Society, 2025) Kishan, D.; Ghosh, S.; Chauhan, S.; Chub, A.Wireless battery charging systems for electric vehicles (EVs) are convenient, safe, and flexible against environmental hazards. Resonant inductive power transfer (RIPT) is the most common method for EV battery charging applications. The inductive coil structure is a major component of the RIPT system, and misalignment between inductive coils is a key issue. This paper proposes an improved, misalignment-tolerant, novel dual orbirect inductive coil structure. The proposed coil structure is designed using finite element modeling (FEM) and investigates magnetic parameters such as self and mutual inductance at various horizontal and vertical misalignment distances. Finally, based on the FEM analysis, the RIPT system is designed for 1 kW, and simulations were carried out in MATLAB. The presented results show that the output voltage exhibits minimal variation across 50% misalignment range. The peak efficiency achieved at full load conditions is 96.2%. © 2025 IEEE.Item Electroactive poly(vinylidene fluoride) fluoride separator for sodium ion battery with high coulombic efficiency(Elsevier B.V., 2016) Janakiraman, S.; Surendran, A.; Ghosh, S.; Anandhan, S.; Adyam, A.Electroactive separators are recent interest in self-charging rechargeable batteries. In this study, electrospun polyvinylidene fluoride (PVDF) is characterized as an electroactive separator for Na-ion batteries. The intrinsic ?-phase with high porosity of the separator is confirmed from X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM) and Atomic Force Microscopy (AFM) studies. The electroactive separator is immersed in 1M NaClO4-ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1 by weight) solution. The physicochemical characteristics of electroactive separator electrolyte (EaSE) were investigated using sodium ion conductivity, ion transference number and contact angle measurements. Linear and cyclic voltammetry studies were also carried out for the electrolyte system to evaluate oxidation stability window. The inherent ?-phases of the separator as obtained by electrospinning has an ionic conductivity of ~ 7.38 × 10- 4 S cm- 1 under ambient condition. Sodium ion cell made from EaSE with Na0·66Fe0.5Mn0·5O2 as cathode and Na metal as anode has displayed a stable cycle performance with a coulombic efficiency of 92% after 90 cycles. © 2016 Published by Elsevier B.V.Item Modelling the land use system process for a pre-industrial landscape in India(Springer Science and Business Media Deutschland GmbH, 2017) Ghosh, S.; Shetty, A.Land in India is changing in a rapid pace since the green revolution during 1960 and industrial policy reforms during 1990. Certainly land cover land use (LCLU) changes have huge impacts on countries overall ecological balance and climate change. The most intriguing fact is LCLU change is an interconnected phenomenon like a system. The understanding of local level LCLU dynamics are yet to get a momentum in India. The present study is an attempt: (1) to examine the land use change drivers active at the studied landscape of coastal Karnataka in India and (2) to model the LCLU changes in pre-industrialized period using Dyna-CLUE model. Binary logistic regression was used to categorize land change drivers and to estimate the probability of changes. Odd ratio from logistic regression indicates that the biophysical drivers are most prominent in determining location of LCLU. They being slope, relative relief, drainage density and availability of ground water are the most influential drivers for most of the land classes. The Dyna-CLUE model is successful to simulate the LCLU change at aggregate level but the spatial allocation needs improvement. © 2017, Springer International Publishing Switzerland.Item Electrochemical characterization of a polar ?-phase poly (vinylidene fluoride) gel electrolyte in sodium ion cell(Elsevier B.V., 2019) Janakiraman, S.; Surendran, A.; Biswal, R.; Ghosh, S.; Anandhan, S.; Adyam, A.A polar ?-phase poly (vinylidene fluoride) (PVDF) membrane is developed through the electrospinning method. PVDF gel electrolyte for sodium ion batteries was obtained by saturating the bare porous membrane in a liquid electrolyte, 1 M NaClO4 in EC: DEC (1:1 vol%). The physical and electrochemical characteristics of the polar ?-phase PVDF membrane are explored by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Atomic force microscope (AFM), sodium ion conductivity, linear sweep voltammetry (LSV) and sodium ion transference number. The ionic conductivity of a polar ?-phase PVDF gel electrolyte exhibited 9.2 × 10?4 S cm?1, higher than the commercially used Celgard® 2400 membrane 0.36 × 10?4 S cm?1 at ambient temperature. The electrochemical expolarations of the sodium ion half-cell (Na2/3Fe1/2Mn1/2O2) as a cathode and sodium metal as a counter electrode) conducted from PVDF gel electrolyte are analysed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CV of the battery showed a pseudo capacitive nature. The equivalent circuit model of the sodium ion cell brought out the effect of dipole moments in the polymer chains on the battery performance. © 2018 Elsevier B.V.Item A new strategy of PVDF based Li-salt polymer electrolyte through electrospinning for lithium battery application(Institute of Physics Publishing helen.craven@iop.org, 2019) Janakiraman, S.; Surendran, A.; Ghosh, S.; Anandhan, S.; Adyam, A.Polyvinylidene fluoride (PVDF) ultrafine fibers with different proportions of lithium nitrate (LiNO3) were fabricated by an electrospinning device. The processing parameters are optimized to 19 wt% PVDF to get a bead free structure. Scanning electron microscope (SEM) and atomic force microscope (AFM) showed the uniform and interconnected porous structure. With the addition of 2 wt% LiNO3, the fiber diameter of the electrospun membrane decreased from 371 to 222 nm. Furthermore, the addition of LiNO3 into the nanofibrous membrane enhanced the ionic conductivity from 0.97 ×10-3 S cm-1 to 1.61 ×10-3 S cm-1 at room temperature after soaking with 1 M LiPF6 (lithium hexafluoro-phosphate) in ethylene carbonate (EC) and diethyl carbonate (DEC) in (1:1 wt%). Compared with the conventional Celgard and pristine PVDF membrane, the salt doped PVDF membranes showed higher electrochemical stability window and lower interfacial resistance. The electrospun membrane separators (ES) were assembled into Lithium cobalt oxide (LiCoO2) as cathode and lithium metal as an anode. The salt doped membrane showed superior discharge, C-rate and stable cycle performance than the commercial Celgard membrane. © 2018 IOP Publishing Ltd.Item Electrospun electroactive polyvinylidene fluoride-based fibrous polymer electrolyte for sodium ion batteries(Institute of Physics Publishing helen.craven@iop.org, 2019) Janakiraman, S.; Surendran, A.; Biswal, R.; Ghosh, S.; Anandhan, S.; Adyam, A.Electrospinning is an efficient technique to produce ultrafine electroactive mat, diameters ranging from few nanometers to micrometers to use as a separator in sodium ion battery. The polyvinylidene fluoride (PVDF) polymer solution was optimized to 19 wt%, applied voltage 25 kV and flow rate of 0.5 ml h-1 to get a bead free ultrafine electroactive structure. The electroactive ?-phase is confirmed by x-ray diffractometer (XRD). Ionic conductivities, electrolyte uptake, wettability, linear sweep voltammetry (LSV) and thermal stability of the electroactive fibrous polymer electrolyte (EFPE) were studied by soaking the separator with a liquid electrolyte of 1 M sodium hexafluorophosphate (NaPF6) dissolved in ethylene carbonate (EC)/propylene carbonate (PC) (1:1 vol%). The EFPE exhibits high ionic conductivity of 1.08 mS cm-1 and electrochemical stability window of 5.0 V versus Na/Na+ under ambient condition. The half-cell containing Na0.66Fe0.5Mn0.5O2 as cathode and EFPE as the separator cum electrolyte showed a stable cycling performance at a current rate of 0.1C. © 2019 IOP Publishing Ltd.Item PVDF/halloysite nanocomposite-based non-wovens as gel polymer electrolyte for high safety lithium ion battery(John Wiley and Sons Inc. cs-journals@wiley.com, 2019) Khalifa, M.; Janakiraman, S.; Ghosh, S.; Adyam, A.; Anandhan, S.Gel polymer electrolyte (GPE) based on electrospun poly(vinylidene fluoride) (PVDF)/halloysite nanotube (HNT) nanocomposite non-wovens was synthesized and its suitability as a separator in lithium-ion battery (LIB) was explored. In this study, HNT played a key role in reducing the average diameter of the electrospun fibers and uplifted the porosity of the non-wovens thereby improving their electrolyte uptake. Due to a reduction in crystallinity and increased % porosity of the PVDF/HNT non-wovens, the ionic conductivity (1.77 mScm?1) and ionic transport across the separator were improved. Moreover, this GPE separator exhibited high tensile and puncture strength with negligible thermal shrinkage and a higher melting temperature compared with a commercially available separator, which is vital from the safety perspective. The cycling performance of Li/GPE/LiCoO2 cell was evaluated and it exhibited a high capacity of 138.01 mAhg?1 with 97% coulombic efficiency for the initial cycle. The cell was stable and retained its high performance with little loss in capacity even after repeated charge–discharge cycles. Such a combination of high ionic conductivity, tensile strength with low thermal shrinkage is seen to be very rare in polymer-based separators. It is noteworthy that this novel GPE outperformed the commercial separator also in the cycle performance. POLYM. COMPOS., 40:2320–2334, 2019. © 2018 Society of Plastics Engineers. © 2018 Society of Plastics EngineersItem An electroactive ?-phase polyvinylidene fluoride as gel polymer electrolyte for magnesium–ion battery application(Elsevier B.V., 2019) Singh, R.; Janakiraman, S.; Khalifa, M.; Anandhan, S.; Ghosh, S.; Adyam, A.; Biswas, K.The gel polymer electrolytes (GPEs) are currently interesting research area in rechargeable batteries. In the present study, synthesis and characterization of electroactive gel polymer electrolyte (EGPE) for Mg-ion batteries application have been investigated. The bead free electroactive polyvinylidene fluoride (PVDF) with high porosity is achieved by an electrospinning process. The ?-phase of PVDF is polar and electroactive with a high dipole moment. Electroactive ?-phase is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Field emission scanning electron microscopy (FESEM) study is done to analyze the structure and morphology of the electroactive membrane. The electroactive gel polymer electrolyte is formed by immersing an electroactive PVDF membrane in 0.3 M magnesium perchlorate (MgClO4) and propylene carbonate (PC) solution. The ionic conductivity of electroactive ?-phase PVDF membrane is achieved to be 1.49 mS cm?1 at 30 °C, which is higher than commercial available polypropylene (PP) Celgard. Tortuosity of electroactive gel polymer electrolyte is found to be 1.44. The voltage stability of the EGPE is stable up to a high voltage of 5.0 V against Mg+2/Mg. The total ionic transference number and magnesium ion transference number of EGPE are also investigated to confirm high ionic conductivity. © 2019 Elsevier B.V.