S. Deki

Studies on PVdF-based gel polymer electrolytes

Abstract A complex of polymer, plasticizer and lithium salts can be used as a solid gel polymer electrolyte in lightweight and rechargeable lithium batteries. Considerable research has been directed towards the development of a gel polymer with high conductivity at room temperature. In this work, a gel polymer electrolyte using polyvinylidene fluoride (PVdF)-1000 (KF), a plasticizer of 1:1 ethylene carbonate (EC) and propylene carbonate (PC), and LiBF 4 salt is optimized. Gel electrolytes have high ionic conductivity, good mechanical stability, a wide electrochemical stable window, and a stable lithium interface. The results of preliminary charge–discharge of cells are discussed in detail.

Growth of metal oxide thin films from aqueous solution by liquid phase deposition method

Abstract The deposition process of iron oxyhydroxide (β-FeOOH) from aqueous solution system of FeOOH–NH 4 F·HF (aq.) with H 3 BO 3 by the liquid phase deposition (LPD) method has been investigated. The effect of initial concentration in the treatment solution and reaction time on microstructure and orientation of the deposited films were studied by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM) observation. The films deposited were constructed by small particles having a crown-like and columnar structure, depending on the concentration range in the treatment solution. XRD measurements revealed that the deposited film preferred the specific direction normal to (211) plane and the dimension of the crystallites varied with the initial concentration of the solution. The deposition process and structure of the films appeared to be strongly affected by the hydrolysis reaction of Fe 3+ ions coordinated by F − and/or partial OH − ions by adding boric acid.

An electrochemical investigation on polyvinylidene fluoride-based gel polymer electrolytes

Abstract Many types of polymer electrolytes have been developed and characterized in the past few years. Recently special attention has been focussed on the development of gel polymer electrolytes consisting of host polymers such as PAN, PVC, PVP, PVS, PMMA, PEGDA and PVdF etc., as they may find unique applications in consumer electronic and electric vehicle products. In the present study, gel polymer electrolytes have been prepared using the solvent casting technique in the presence of PVdF-1015 (SOLEF), EC+PC as a plasticizer, and LiBF 4 salt. The influence of the amount of polymer, plasticizer and LiBF 4 on the gel electrolytes has been studied using XRD, DSC, AC impedance and charge–discharge studies.

Performance evaluation of PVdF gel polymer electrolytes

A series of gel polymer electrolytes containing PVdF as homo polymer, a mixture of 1:1 Ethylene Carbonate (EC) : Propylene Carbonate (PC) as plasticizer and lithium-bistrifluoromethane sulphone imide [imide — LiN (CF3SO2)2] has been developed. Amounts of polymer (PVdF), plasticizer and the imide lithium salt have been varied as a function of their weight ratio composition in this regard. Dimensionally stable films possessing appreciable room temperature conductivity values have been obtained with respect to certain weight ratio compositions. However, conductivity data have been recorded at different possible temperatures, i.e., from 20 °C to 65 °C. XRD and DSC studies were carried out to characterize the polymer films for better amorphicity and reduced glass transition temperature, respectively. The electrochemical interface stability of the PVdF based gel polymer electrolytes over a range of storage period (24 h – 10 days) have been investigated using A.C. impedance studies. Test cells containing Li/gel polymer electrolyte (GPE)/Li have been subjected to undergo 50 charge-discharge cycles in order to understand the electrochemical performance behaviour of the dimensionally stable films of superior conductivity. The observed capacity fade of less than 20% even after 50 cycles is in favour of the electrochemical stability of the gel polymer electrolyte containing 27.5% PVdF −67.5 % EC+PC −5% imide salt. Cyclic voltammetry studies establish the possibility of a reversible intercalation — deintercalation process involving Li+ ions through the gel polymer electrolyte.