Electrochimica Acta 46 (2001) 1783 – 1791 Ion transport theory of nonaqueous electrolytes. LiClO 4 in -butyrolactone: the quasi lattice approach A. Chagnes a , B. Carre ´ a , P. Willmann b , D. Lemordant a, * a Laboratoire Physicochimie des Interfaces et des Milieux Re ´actionnels (EA2048), Uniersite ´ de Tours, Faculte ´ des Sciences, parc de Grandmont, F 37200 Tours, France b CNES, 18 Aenue E. Belin, F 31055 Toulouse Cedex, France Received 3 July 2000; received in revised form 10 November 2000 Abstract As a part of a study on the optimisation of the electrolyte for high-density energy lithium batteries, transport properties of concentrated LiClO 4 solutions in -butyrolactone (BL) have been investigated. The effect of the salt concentration (C ) on the viscosity ( ) of BL solutions has been discussed in term of the Jones–Dole equation. At concentrations higher than 0.2 M, the molar conductivity ( ) of LiClO 4 solutions follow a C 1/3 cube root law which is predicted by the quasi lattice model first introduced by Gosh. In this model, the ions of the strong binary electrolyte are distributed in a lattice-like arrangement (fcc). The experimental value found for the slope of  vs. C 1/3 relation is in fair agreement with the calculated one. The effect of the temperature on the viscosity and the conductivity of electrolyte solutions have been examined. These two transport processes are well described by Arrhenius type laws from which the activation energies for the viscosity E a and conductivity E a are deduced. The variations of E a and E a with salt concentration are respectively dependent on C and C 4/3 as predicted by the quasi lattice model. © 2001 Elsevier Science Ltd. All rights reserved. Keywords: Lithium battery; Organic electrolytes; Butyrolactone; Viscosity; Conductivity; Activation energy; Quasi-lattice www.elsevier.nl/locate/electacta 1. Introduction In an electrolyte solution, long-range electrostatic attractions and repulsions occur, in addition to short- range van de Waals forces such as ion–dipole interac- tions, dipolar and polarisation interactions. The logarithm of the activity coefficient of the electrolyte  i can be expressed as a power series in m i , the molality of the electrolyte, which fulfils the Gibbs – Duhem con- straint (Eq. (1)): ln  i =a m i n , +b m i 2 +c m i 3 +… (1) In this expression, n is any fraction between zero and unity. The first term represents the long-range electro- static attraction and repulsion, whereas, the second and third terms are representative of the short-range van der Waals interactions. In most dissociating solvents, the slope of ln  i versus the square root of the molality m i 1/2 or the molar concentration C i 1/2 approach linearity at low concentrations, though experimental results at moderate or high concentration are better described when m i 1/3 (or C i 1/3 ) is used. The linearity of the cube root law is expected when the solute forms an expansive ionic lattice in the solution. Ghosh [1] was the first to propose that, when a ionic crystal is dissolved in water, ions could be at positions corresponding to an ionic lattice. Even if the thermal agitation destroys the lattice organisation for high dis- * Corresponding author. Fax: +33-247366953. E-mail address: lemordant@univ-tours.fr (D. Lemordant). 0013-4686/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.