DOI: 10.1002/elan.201400232 Characterization and Electrochemical Properties of P(VdF-co-HFP) Based Electrospun Nanocomposite Fibrous Polymer Electrolyte Membrane for Lithium Battery Applications O. Padmaraj, [a] M. Venkateswarlu, [b] and N. Satyanarayana* [a] 1 Introduction Solid polymer electrolytes (SPEs) have unique properties, such as flexibility in design, improved safety, longer shelf life, higher energy density, etc., as compared to liquid electrolytes used in rechargeable lithium batteries. De- spite of several advantages, SPEs also suffers with low ionic conductivity at ambient temperature [1–2]. Re- search focus has been paid to improve the electrical and interfacial properties of SPEs used in advanced Lithium batteries with high specific energy and specific power for next generation applications. In order to develop novel SPE membranes for high energy density Li-ion batteries, several approaches have been employed such as blending [3], plasticizing [4] and composites [5–8]. Recent past, re- searchers have put effort to develop nanocomposite poly- mer electrolyte membranes with good thermal, mechani- cal, chemical and electrochemical stabilities by incorpo- rating ceramic fillers, such as nanosize particles of TiO 2 , SiO 2 , Al 2 O 3 , ZrO 2 , MgAl 2 O 4 , etc [7–10]. The polymer electrolytes based on poly(vinylidene fluoride) (PVdF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF- co-HFP), poly(methyl methacrylate) (PMMA) and poly(- acrylonitrile) (PAN) were widely used as host polymers [11–15]. Among them, P(VdF-co-HFP) copolymer was found to be a suitable candidate as it has good electro- chemical stability, affinity to electrolyte solution and high dielectric constant (e  8.4) [16, 17]. A wide range of synthesis methods, such as solution casting [7], hot press [18], plasticizer extraction [12], phase inversion [14] and electrospinning, etc., [15, 16] have been adopted for the development of porous poly- mer electrolyte membranes. Among them, electrospin- ning technique has been considered as the most suitable tools to prepare an interlaying of nanofibers that gener- ates large porosity with fully interconnected pore struc- ture, which facilitates more ion transport in the composite polymer electrolyte membranes [15]. To the best of authors knowledge there are no reports on the development of electrospun nanocomposite P(VdF-co-HFP)/ZnAl 2 O 4 polymer electrolyte membranes by electrospinning technique. Hence, authors have devel- oped different composition of nanocomposite P(VdF-co- HFP)/ZnAl 2 O 4 fibrous polymer membranes by dispersion of various x wt% ZnAl 2 O 4 (x = 1, 2, 3, 5 and 8) fillers con- [a] O. Padmaraj, N. Satyanarayana Department of Physics, Pondicherry University Kalapet – 605 014, India. *e-mail: nallanis2011@gmail.com [b] M. Venkateswarlu Amara Raja Batteries Ltd, Karakambadi – 517 520, India tel: + 91 413 2654404, fax: + 91 413 2655348 Abstract : Effect of ZnAl 2 O 4 nanofillers concentration on the physical and electrochemical properties of electro- spun P(VdF-co-HFP) based nanocomposite electrolyte membranes were studied. By optimizing the spinning pro- cess parameters, the bead free and an average range (0.5– 1.0 mm) of diametered fibrous membranes were devel- oped using an electrospinning technique. The nanocom- posite fibrous membrane with 5 wt% ZnAl 2 O 4 fillers showed reduction of crystallinity, good thermal stability and smooth morphology were studied by X-ray diffrac- tion, differential scanning calorimetry and scanning elec- tron microscopy techniques. The fibrous P(VdF-co-HFP) copolymer and nanocomposite P(VdF-co-HFP)/ZnAl 2 O 4 polymer electrolytes were prepared by soaking the pre- pared electrospun fibrous membranes in 1 M LiPF 6 in EC: DEC (1 : 1, v/v) and evaluated the wet-ability proper- ties by electrolyte uptake method. The activated nano- composite fibrous polymer electrolyte membrane with 5 wt% ZnAl 2 O 4 fillers content shows high ionic conduc- tivity of 1.59  10 3 Scm 1 at room temperature and good electrochemical stability window higher than 4.3 V. Elec- trochemical performance of Li/PE, NCPE/LiCoO 2 CR 2032 coin cells containing the prepared fibrous polymer electrolyte (PE) and nanocomposite polymer electrolyte (NCPE) membranes with 5 wt% ZnAl 2 O 4 filler content is evaluated at current density 0.1 C-rate over the potential range 2.8–4.2 V. Keywords: Electrospinning · Electrochemical stability · Thermal · ZnAl 2 O 4 filler Topical Issue INDIA www.electroanalysis.wiley-vch.de  2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Electroanalysis 2014, 26, 2373 – 2379 2373 Full Paper