Transport properties of lithium-ion in green nonaqueous solutions and polymer ionic exchange membranes: an attempt to elaboration of ecological Li-ion battery

Abstract

Organic solutions are considered as good electrolytes yielding higher lithium-ion (Li-ion or Li+) transference numbers for lithium-ion batteries during charge and discharge processes. However, owing to ecological reasons, the transference numbers of this metal ion in green viscous solvent such as glycerol at various concentrations and temperatures have been measured by means of the concentration cell and Bruce–Vincent techniques. An average value of the transport number less than 0.5 was obtained at 298.15 K, suggesting that the solvated Li+ carries less electric charges than the larger size chloride anion. The results were then compared to a recent study utilizing molecular dynamics simulation where it was confirmed the smallness values of the Li+ transference number. Besides, Hittorf’s method using the polymer cation exchange membrane (nafion 117) has been also investigated and shows the highest transport, suggesting its advantageous utilization in ecological lithium-ion batteries. Furthermore, the concentration polarization of membrane equilibrated with the electrolyte solution of lithium was carried out by means of voltamperometry that allowed recording the current–voltage characteristic. It yielded, however, low limiting current density, indicating that the polarization is more pronounced with such light metal, in contrast to larger diffusion constant and average transport number.