The Temperature Dependence of the Properties of Electrolyte Solutions. IV. Determination of Cationic Transference Numbers in Methanol, Ethanol, Propanol, and Acetonitrile at Various Temperatures

Abstract

Cationic transference numbers and conductance data of KSCN and Me4NSCN in methanol (‐15°C to + 25°C), KSCN in ethanol (‐5°C to + 25°C) and propanol (+ 10°C and +25°C), Me4NClO4 and Et4NClO4 in acetonitrile (‐35°C to +25°C) were determined at electrolyte concentrations from 10−3 to 10−2 mol · kg−1. The transference numbers obtained by a moving boundary method were corrected for the changes of the calibration volume resulting from anodic reactions, conductance of the solvent and Joule heating. The data are discussed on the basis of transport equations which take into account short range interactions in the ion distribution functions.

Salt Diffusion Coefficients, Concentration Dependence of Cell Potentials, and Transference Numbers of Lithium Difluoromono(oxalato)borate-Based Solutions

“…Cationic transference numbers are shown in Table . As can be seen, the transference numbers decrease with increasing concentration as expected for transference numbers with a value < 0.5 at infinite concentration. , …”

“…As can be seen, the transference numbers decrease with increasing concentration as expected for transference numbers with a value < 0.5 at infinite concentration. 3,31 A comparison of transference numbers measured by electrochemical methods or by NMR method 3 shows that ion pair diffusion plays an important role. The Haven ratio can give information about this transport phenomenon.…”

Ion Transport in Organic Electrolyte Solutions for Lithium-ion Batteries and Beyond

“…where I is the disk electrode current, n is the number of electrons transferred in the elementary reaction step, F is the Faraday constant, A is the disk electrode area (cm 2 ), D is the diffusion coefficient (cm 2 /s), ν is the kinematic viscosity (cm 2 /s), and ω is the angular velocity of the disk electrode (rad/s). The diffusion coefficient is obtained from the slope of the I versus ω 1/2 plot, which according to Equation (11), should be a straight line passing through the origin [43].…”

“…Another method for measuring the transference number is based on experiments using a concentration cell and determining the thermodynamic factor, (1 + ∂ln 𝑓 ± (𝑐) 𝜕 ln 𝑐 ), of binary solutions [62], where f± is the mean molar activity coefficient, which is the average of the mean molar activity coefficients of the cation and the anion, by measuring the lithium concentration dependent potential in a lithium electrode versus ferrocene/ferrocenium redox couple used as an internal standard [63,69]. The concentration dependence of the transference number, t+, is usually not known a priori [11]. Alternatively, it can be assumed a constant transference number within a concentration range (δc) about an average concentration, c0 (δc << c0); thus, one can determine an average transference number within the differential concentration range t+(c0+δc).…”

“…Although liquid organic (non-aqueous) electrolytes offer high conductivity (1-10 mS/cm) and well-dissociated ions for concentrations > 1 M, they have a cation transference number below 0.5, which implies that the total ionic conductivity results from the anion migration [6]. However, contradictory results have been reported regarding transference number measurements, concentrations, and temperature dependence by different methods [9][10][11][12]. Ion transport is based on ion solvation which is favored by aprotic solvents with a high dielectric constant [13,14], ion dissociation which depends on temperature [15], ion motion through the solvent, long-range electrostatic interactions, and viscosity of the solvent.…”