Characterization of ionic liquid added poly(vinyl alcohol)-based proton conducting polymer electrolytes and electrochemical studies on the supercapacitors Chiam-Wen Liew, S. Ramesh * , A.K. Arof Centre for Ionics University of Malaya, Department of Physics, Faculty of Science, University of Malaya, Lembah Pantai, 50603 Kuala Lumpur, Malaysia article info Article history: Received 25 March 2014 Received in revised form 10 September 2014 Accepted 29 September 2014 Available online xxx Keywords: Poly(vinyl alcohol) Ionic liquid Proton conductive Supercapacitors Carbon nanotubes abstract The preparation of poly(vinyl alcohol) (PVA)/ammonium acetate (CH 3 COONH 4 )/1-butyl-3- methylimidazolium bromide (BmImBr) proton conducting polymer electrolytes is done by solution casting method. Upon inclusion of 60 wt.% of BmImBr, the maximum ionic con- ductivity of (9.29 ± 0.01) mScm 1 is achieved at ambient temperature. Ionic liquid added polymer electrolytes exhibit lower glass transition temperature (T g ), crystalline melting temperature (T m ) and crystallization temperature (T c ) than ionic liquid-free polymer elec- trolyte. The amorphous character of the most conducting polymer electrolyte has been proven using differential scanning calorimetry (DSC). Addition of ionic liquid not only extends the electrochemical potential window of the electrolyte, but also improves the thermal stability of the polymer electrolyte. Activated carbon/carbon black/carbon nano- tube electrode is prepared and used in electrochemical double layer capacitors (EDLCs) fabrication. Based on the results, EDLC containing ionic liquid added polymer electrolyte exhibits better electrochemical properties. This EDLC possesses higher specific capacitance than that of supercapacitor comprising of ionic liquid free-based polymer electrolyte. The specific capacitance of 21.89 Fg 1 is obtained from cyclic voltammetry (CV). This value is in good agreement with EIS and galvanostatic chargeedischarge findings. The EDLC remains stable upon 250 cycles of charging and discharging processes. Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Introduction Electrochemical double layer capacitor (EDLC) is an energy storage-based electrochemical devices. ELDC generally com- prises two electrodes and an ion conducting electrolyte. Activated carbon (AC) is a predominant electrode material used in EDLCs because of its attractive properties. Large spe- cific surface area (1000e2500 m 2 g 1 ), high porosity and low cost are the advantages of AC [1,2]. However, high micropo- rosity (pore dimension: <2 nm) of activated carbon could limit the accessibility of charge carriers into the micropores of AC. It is because the bigger ion size serves as a hurdle for diffusion into the smaller pores [1,3]. Therefore, carbon nanotubes * Corresponding author. Tel.: þ60 3 7967 4391; fax: þ60 3 7967 4146. E-mail addresses: liewchiamwen85@gmail.com (C.-W. Liew), rameshtsubra@gmail.com (S. Ramesh). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2014) 1 e11 Please cite this article in press as: Liew C-W, et al., Characterization of ionic liquid added poly(vinyl alcohol)-based proton conducting polymer electrolytes and electrochemical studies on the supercapacitors, International Journal of Hydrogen Energy (2014), http://dx.doi.org/10.1016/j.ijhydene.2014.09.160 http://dx.doi.org/10.1016/j.ijhydene.2014.09.160 0360-3199/Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.