Faculty Publications
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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 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 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 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.Item A high thermally stable polyacrylonitrile (PAN)-based gel polymer electrolyte for rechargeable Mg-ion battery(Springer, 2020) Singh, R.; Janakiraman, S.; Khalifa, M.; Anandhan, S.; Ghosh, S.; Adyam, A.; Biswas, K.The ionic conductivity and thermal stability of the electrolyte-separator system is an essential parameter for improving battery performance and safety. The present work addresses the high thermally stable gel polymer electrolyte (GPE) using polyacrylonitrile (PAN) as a polymer membrane and magnesium perchlorate in propylene carbonate (Mg(ClO4)2-PC) as a liquid electrolyte. The PAN based polymer membrane is prepared by electrospinning process which produces a bead free and uniformly distributed nanofibers. The electrospun PAN based GPE is characterized by different physical and electrochemical techniques like X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, ionic conductivity, linear sweep voltammetry, magnesium ion transference number and electrochemical impedance spectroscopy. The ionic conductivity of PAN is 3.28 mS cm?1, compared to that of PP Celgard is 1.97 × 10–4 mS cm?1 at 30 °C. The electrochemical stability of PAN is 4.6 V and also exhibits excellent interfacial stability with magnesium metal. The results showed that the PAN-based GPE has higher ionic conductivity and thermal stability than the polypropylene (PP) Celgard membrane. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.