Characterization of Poly(vinyl alcohol)/Potassium Chloride Polymer Electrolytes for Electrochemical Cell Applications Y. Pavani, M. Ravi, S. Bhavani, A.K. Sharma, V.V.R. Narasimha Rao Department of Physics, Sri Venkateswara University, Tirupati-517 502, India A solid polymer electrolyte system based on poly(vinyl alcohol) (PVA) complexed with potassium chloride (KCl) salt was prepared by using solution cast technique. The complexation of KCl salt with the polymer was confirmed by X-ray diffractrometer and Fourier trans- form infrared spectroscopy. Differential scanning calo- rimetry was used to determine the melting tempera- tures and crystallinity of the pure PVA and complexed films. Ionic conductivities of the electrolytes have been determined by AC impedance studies in the tempera- ture range 303–373 K. The conductivity was found to increase with the increase in dopant concentration and temperature. Transference number data suggests that the charge transport in this polymer electrolyte system is mainly due to ions. Optical absorption studies were made in the wavelength range 200–800 nm on pure and KCl doped PVA films. The absorption edge, direct band, and indirect band gap values were evaluated. It was found that the energy gaps and band edge values shifted to lower energies on doping. Electrochemical cells were fabricated with the configuration of K/(PVA þ KCl)/(I 2 þ C þ electrolyte) and discharge characteris- tics were studied under a constant load of 100 kO. Var- ious cell parameters, such as open circuit voltage, short circuit current, power density, and energy density were determined. POLYM. ENG. SCI., 00:000–000, 2012. ª 2012 Society of Plastics Engineers INTRODUCTION In recent years, there has been an increasing interest to develop the polymer electrolytes for various applications, such as high energy density batteries, fuel cells, electro- chemical capacitors, solar cells, gas sensors, etc. due to their versatility and dimensional stability [1–3]. The advantages of polymer electrolytes over other solid elec- trolytes are due to their unique mechanical and electrical properties; ease of fabrication into films of desirable sizes and interactions to strengthen the electrode–electrolyte contact. The study of polymer electrolytes was launched by Fenton et al. [4] in 1973, but their technological sig- nificance was not appreciated until the research under- taken by Armand et al. [5, 6], a few years later. Initially, polyethylene oxide-(PEO) based electrolytes were investi- gated. However, PEO-based polymer electrolytes showed ionic conductivity of the order of 10 210 S cm 21 . Due to the poor performance of this electrolyte, much effort has been devoted to improve the ambient ionic conductivity of polymer electrolytes by improving the cation migration in the amorphous domain. Since ions primarily transport in amorphous phase, many investigations, which aimed to improve ionic conductivity have focused on increasing the amorphous phase of the material. Many attempts have been made on various polymers such as poly (methyl methacrylate) (PMMA), poly (vinyl chloride) (PVC), polyacrylonitrile (PAN), and poly(vinyl alcohol) (PVA) for the purpose of designing polymer electrolyte systems. In the present investigations, PVA has been chosen as the host polymer due to its chemical stability, easy proc- essability to form film [7], and its good charge storage capacity. It has a carbon chain back bone with hydroxyl groups attached to methane carbons. These O–H groups can be source of hydrogen bonding and hence assist the formation of polymer electrolytes. A few attempts have tried electrolytes based on potassium complexed films. Apart from, the scientific interest, the use of potassium has several advantages over their lithium counter parts; potassium is available in abundance at a cheaper cost than lithium. Furthermore, the softness of this material makes it easier to achieve and maintain contact with other com- ponents in the battery. On other hand, potassium chloride (KCl) is the fast conducting salt in a number of crystal- line and amorphous materials, its incorporation in a poly- meric system may be expected to enhance its electrical and optical performance. In this study, we report solid polymer electrolyte films of pure PVA and PVA complexed with KCl systems. Sev- eral experimental techniques like X-ray diffractrometer (XRD), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), transference number were carried out to characterize these polymer electrolytes. Using these electrolytes, electrochemical cells were fabri- Correspondence to: V.V.R. Narasimha Rao; e-mail: nraovvr@gmail.com DOI 10.1002/pen.23118 Published online in Wiley Online Library (wileyonlinelibrary.com). V V C 2012 Society of Plastics Engineers POLYMER ENGINEERING AND SCIENCE—-2012