Molar conductivities of concentrated lithium chloride–glycerol solutions at low and high temperatures: application of a quasi-lattice model

Abstract

Conductivities of concentrated solutions of lithium chloride in glycerol were measured for concentrations ranging from 0.005 to 1.5 mol.dm⁻³. The conductivity dependencies were analysed successively using the Debye–Huckel–Onsager limiting law (DHO) at very low concentrations, the Fuoss equation of 1978 up to 0.1 mol.dm⁻³, the Casteel–Amis empirical equation and the quasi-lattice model (QLM) at moderate and higher concentrations. The molar conductivities at infinite dilution, obtained using DHO and QLM were quite different from each other, because the salt forms contact pairs which were underestimated in the Λ = f(C^1/3) in QLM, as it may well be proved by Raman spectroscopy. Besides, the value of Madelung constant suggests that LiCl crystallises face centred cubic (FCC) at higher concentrations. On the basis of Raman spectroscopy analysis of previous lithium salts, we assume that the dissociation coefficient varies slightly with concentration and fraction of paired ion constant, the QLM equation is applied successfully in the concentration range used in this study. The temperature dependency of conductivity was also described using the Vogel–Tamman–Fulcher (VTF) empirical equation where the Arrhenius type was found. The results also suggest that as NaCl, LiCl can be considered as a structure maker electrolyte.

Keywords:

• LiCl
• glycerol
• concentrated solutions
• lithium-battery
• clean energy