Mechanics, Materials Science & Engineering, July 2017 – ISSN 2412-5954
Conductivity Enhancement Studies on Poly (Acrylonitrile)-Poly (Vinylidene Fluoride) Composite Polymer Electrolytes 1
M. Usha Rani1, Ravi Shanker Babu1, S. Rajendran2, R. Arunkumar1 1 – Department of Physics, School of Advanced Sciences, VIT University, Vellore 2 – Department of Physics, Alagappa University, Karaikudi, India DOI 10.2412/mmse.8.72.942 provided by Seo4U.link
Keywords: polymer electrolyte, composite, inert filler, plasticizer, impedance studies. ABSTRACT. Composite electrolyte films consisting of poly (acrylonitrile), poly (vinylidene Fluoride), ethylene carbonate, propylene carbonate, lithium tetra fluoroborate (LiBF4) and also titanium dioxide (TiO2) particles have been prepared by solution casting technique. The effect of inorganic filler on the conductivity of the blended polymer electrolyte has been studied. A conductivity of 3.1 x 10 -5 S cm-1 is achieved at room temperature for the composition PAN-PVdF–LiBF4-EC-PC (21-10-8-33.3-27.7), whereas it improves two orders of magnitude (i.e. 5.624 ×10 −3 S cm−1) upon dispersing fine particles of TiO2 as inert filler into the matrix. The role of ceramic phase is to increase the ionic conductivity and to reduce the melting temperature which is ascertained from conductivity and thermo gravimetric/differential thermal analysis respectively.
Introduction. Decades ago, Wright and co-workers [1] pioneered the research on solid polymer electrolytes and later Armand et al. [2] realized the potential applications of these materials in batteries with high specific energy and other ionic devices. Even though, polymer electrolytes are advantageous in terms of shape, geometry, mechanical strength and the potential for strong electrode electrolyte contact, they have some disadvantages like, poor interfacial properties, low ionic conductivity at ambient temperature [3]. Generally polymer electrolytes show practical ionic conductivity only at higher temperatures, and their melting points, and at such high temperatures, they exist in a ‘quasi-liquid’ state and become very flexible, and therefore show very poor dimensional stability. A dimensionally polymer electrolyte film easily cause a short circuit between a cathode and an anode when it is applied to all solid-state lithium battery. Increasing ionic conductivity by increasing the salt concentration is ruled out because, higher salt content may favour reduction in crystalline fraction of polymer but causes high ion-pairing interaction, which lead to salt aggregation [4]. Hitherto several studies have been made primarily on the enhancement of ionic conductivity at ambient temperature via various approaches such as blends, copolymers, comb-shaped polymers, cross-linked networks, addition of plasticizers and incorporation of ceramic fillers onto the polymer matrix [5]. Studies have revealed that plasticized polymer electrolytes lose their mechanical strength upon addition of plasticizer and lead poor interfacial properties. The mechanical properties of the polymer electrolytes can be increased either by chemical or physical curing which incurs high processing cost. Recently, phase-inversion technique has drawn the attention of many researchers, despite its advantages it suffers from poor rate capability [6]. Very recently, studies reveal that the composite polymer electrolytes could offer lithium batteries with reliability and improved safety [6]. Many reports are available on the effect of ceramic oxides on polymer electrolytes such as, physical and electrochemical properties, increase in cation transference number and improvement of interfacial stability between the composite polymer electrolyte and lithium metal. In this work, novel composite polymer electrolyte composed of PAN-PVdF-EC-PC-LiBF4-TiO2 as promising electrolyte 1
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/
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