Available online at www.sciencedirect.com Electrochimica Acta 53 (2007) 1476–1480 More studies on the PVOH–LiH 2 PO 4 polymer system V.H. Zapata a,∗ , W.A. Castro a , R.A. Vargas a , B.-E. Mellander b a Departamento de F´ ısica, Universidad del Valle, A.A. 25360 Cali, Colombia b Physics and Engineering Physics, Chalmers University of Technology, 41296 G¨ oteborg, Sweden Received 11 December 2006; received in revised form 26 May 2007; accepted 26 May 2007 Available online 3 June 2007 Abstract Polymer electrolytes based on poly(vinyl alcohol) (PVOH) and lithium dihydrogen-phosphate (LiH 2 PO 4 ) with molar ratio of x = 0.07, 0.10 and 0.14 were prepared in order to investigate the mechanism of ionic motion. Admittance spectroscopy measurements were used to study electrical conductivity relaxation on both anhydrous and hydrated samples in the 5 Hz to 13 MHz frequency range and temperatures ranging from 25 to 150 ◦ C. The conductance, G, shows dispersion above a crossover frequency, f p . This behavior is typical of systems in which correlated ionic motions in the bulk material are responsible for ionic conductivity. For hydrated samples, results reveal that the temperature dependence of the dc- conductivity, σ 0 and the characteristic frequency, f p , shows Arrhenius-type behavior with the same energy, E σ . However, for anhydrous conductivity, a Vogel–Tamman–Fulcher (VTF) behavior is shown for both σ 0 (T) and f p (T), with the same pseudo activation energy, B and B σ , respectively, thus indicating that they are correlated with chain mobility. © 2007 Published by Elsevier Ltd. Keywords: Poly(vinyl alcohol); ac conductivity; Power law; Non-Debye relaxation 1. Introduction Solid polymer electrolytes (SPEs), typically based on amor- phous forms of poly(ethylene oxide) (PEO), are well establish as solid state ionic conductors in which ion transport includes besides ion motion, local motion of polymer segments and inter- and intrapolymer transitions between coordinating sites formed by the adjacent polyether oxygens [1]. As a consequence, ionic transport in these materials is highly correlated. Different lev- els of interactions between the basic “molecular” units have been inferred from frequency-dependent conductivity studies. An example is that of SPEs based on polypropylene oxide (PPO) containing lithium perchlorate (LiClO 4 ) as a salt [2] and other polymer electrolytes with polyether chains [3–7] which are found to displays similar characteristics of their complex con- ductivity spectra. These measurements strongly indicate that the temperature, composition and types of ion–ion and ion–polymer interactions influence the very shape of those spectra and fre- quency range of those spectra. ∗ Corresponding author. Tel.: +57 2 3394610; fax: +57 2 3393237. E-mail address: vizapata@calima.univalle.edu.co (V.H. Zapata). There has been interest in using poly(vinyl alcohol) (PVOH) as a polymer matrix in view of its film-forming capacities, hydrophilic properties, low cost and possible coupling of charge transport with the motions of its hydroxyl group [8,9]. Sev- eral papers [10–12] have reported anhydrous conductivity of the order of 10 -8 to 10 -4 S/cm for lithium salts complexed with PVOH. Moreover, due to the hydrophilic properties com- bined with the good swelling ability, the PVOH has also been used to develop solid proton polymer electrolytes through addi- tion of an acidic aqueous solution [13–15]. Conductivity as high as 10 -2 S/cm has been reported for these gel-type mem- branes at room temperature (see, for instance Ref. [15]). Other ion-conducting SPEs, have also been studied for various appli- cations, see for instance Refs. [16,17]. The aim of this study was to study conductivity relaxation in order to establish a con- nection between the experimentally measured quantities and the complex structure within which ion diffuse, that is, in terms of coordination sites in the polymer host and polymer segmen- tal motion. Given that it is widely understood that conduction of ions in polyether electrolytes is quite strongly coupled to the polymer backbone motions, it is desirable to investigate this mechanism in electrolytes based on other vinyl polymers having hydroxyl side groups. 0013-4686/$ – see front matter © 2007 Published by Elsevier Ltd. doi:10.1016/j.electacta.2007.05.063