R. Subadevi

Investigations on the effect of various plasticizers in PVA-PMMA solid polymer blend electrolytes

Solid polymer electrolyte films containing poly(vinyl alcohol) (PVA)/PMMA–LiBF4–X (X=EC, PC, DEC, GBL) were prepared by solvent casting technique. Complexation of the prepared electrolytes is studied by XRD, FTIR analyses. Ionic conductivities of the electrolytes have been determined by ac impedance studies in the temperature range 302–373 K. The temperature-dependent ionic conductivity plots seem to obey the VTF relation. Dielectric relaxation studies of the polymer electrolyte have been undertaken and the results are discussed. Thermal stability of the prepared electrolytes has been examined using TG/DTA analysis. Cyclic voltammetry has been performed for the electrolyte films to study their cyclability and reversibility. The ionic transport in the polymer electrolytes has been discussed on the basis of free volume theory. The maximum ionic conductivity (1.2886×10−3 S/cm) has been observed for EC-based complex because of the higher dielectric constant among the other plasticizers.

An efficacy of ‘nano’ in brannerite-type CoV2O6 conversion electrode for lithium batteries

Among the classical anodes, conversion anodes play a unique role due to their capability to provide higher initial discharge capacity than the theoretical capacity. Poor capacity retention and voltage hysteresis exhibited by classical conversion anodes are the major obstacles for their commercialization in lithium battery market. Nanotechnology may be a suitable contrivance to tackle this problem. To our knowledge, this is the first attempt to synthesize brannerite-type nano sized cobalt vanadate by rheological phase reaction method and use it as a conversion anode in lithium batteries. Although this material provides a high initial irreversible capacity of around 600 mA h g−1 in its preliminary cycle, stabilization of capacity with approximately 100% coulombic efficiency and considerable low voltage hysteresis in the proceeding cycles may place this material in the limelight for its development as a commercially available anode material. The electrochemical conversion of CoO nanoparticles into Co quantum dots occurred in an amorphous lithiated vanadium oxide matrix, which functioned as a source of reactive sites, as well as a separator to preserve the nanoparticles against further agglomeration, thereby, offering a better rate capability.

Synthesis and electrochemical characterization of olivine-type lithium iron phosphate cathode materials via different techniques

High-potential, eco-friendly LiFePO4 cathode materials were synthesized by polyol, hydrothermal, and solid-state reaction methods. The polyol technique was carried out without any special atmosphere and postheat treatment. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectrometry (XPS), and charge-discharge and cyclic voltammetry tests. The LiFePO4 prepared via polyol technique exhibits good electrochemical performance than other method samples do.