Materials Chemistry and Physics 97 (2006) 330–336 Electrochemical studies on [(1 - x)PVA–xPMMA] solid polymer blend electrolytes complexed with LiBF 4 M. Sivakumar a,∗ , R. Subadevi b , S. Rajendran b , N.-L. Wu a , J.-Y. Lee c a Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan, ROC b Department of Physics, Alagappa University, Karaikudi 630 003, Tamilnadu, India c Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Taejon 305 702, South Korea Received 17 June 2005; received in revised form 20 July 2005; accepted 9 August 2005 Abstract PVA–PMMA-based electrolyte films containing fixed LiBF 4 salt are prepared using solvent casting technique. The complexation has been confirmed from XRD and FTIR spectral studies. The ac impedance studies are performed to evaluate the ionic conductivity of the polymer electrolyte membranes in the range 302–373 K and the temperature dependence seems to obey the VTF relation. The influence of blend compositions on the ionic conductivity has been discussed. The maximum ionic conductivity value for PVA (60wt.%)–PMMA (40 wt.%)–LiBF 4 (10 wt.%) system is found to be 2.801 × 10 -5 S cm -1 at 302 K. Thermal analysis and CV studies have been performed and reported here. © 2005 Elsevier B.V. All rights reserved. Keywords: Polymer; FTIR; Impedance studies; TG/DTA 1. Introduction In recent past electrochemical energy storage devices have a tremendous role in technical applications like computers, communication devices, industrial controls, electric vehi- cles, space ships, laboratory equipments, etc. Moreover they have stringent need in the portable electronic market like solar cells, pacemakers, remote controls and even in toys. In these emerging technologies they are having an exclu- sive demand for long life, environmentally friendly, low cost, reliable rechargeable batteries with specific energy power as expected [1]. Such power was obtained by using the liq- uid electrolytes due to its hectically moving charge carriers. On the other hand, to overcome the drawbacks of liquid electrolytes like leakage, reaction with the electrode, poor electrochemical stability, the solid polymer electrolytes are extensively studied in the past decades. Due to its excel- lent mechanical, thermal stability and high ionic conductiv- ∗ Corresponding author. Tel.: +886 2 33663059. E-mail address: susiva@rediffmail.com (M. Sivakumar). ity solid polymer electrolytes yield the attention of many researchers towards the identification and development of solid polymer electrolytes in optimum number of applica- tions such as computer memory back up, smart windows, photovoltaic cells, fuel cells, electric vehicle traction and space power applications, etc. In order to remain structurally stable during manufacturing, cell assembly and no leakage from cell container, the polymer electrolytes should pos- sess good mechanical stability. To incorporate this stability the polymer blending is one of the most promising ways. When two or more polymers give rise to a homogeneous mixture, miscible or compatible blend is formed in which one polymer is adopted to absorb the electrolytes’ active species while another remains as an undissolved, inert second phase providing toughness to the polymer electrolyte films. Also Berthier et al. [2] established that ionic conductivity in polymer electrolytes is associated with amorphous phase of studied samples. Among the various methods to produce high ionic conduction, flexibility, good mechanical strength and amorphous nature, polymer blends are the most promis- ing and feasible approach [3]. The blend-based polymer 0254-0584/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.matchemphys.2005.08.018