Application of microelectrodes to the study of the Li|Li+ couple in ether solvents. Part 2.—Temperature dependence

Abstract

Cyclic voltammetry and potential step experiments at microelectrodes have been used to probe the influence of temperature (over the range 253–333 K) on the deposition and dissolution of lithium metal in tetrahydrofuran containing lithium hexafluoroarsonate. The temperature strongly influences both the kinetics of nucleation of the lithium phase on other conducting materials (Ni, Cu, C) and of the Li|Li⁺ couple after the new phase is formed. The exchange current density for the Li|Li⁺ couple at 293 K is found to be 4 mA cm^–2 for a solution containing 0.84 mol dm^–3 Li⁺, a much higher value than previously reported in the literature, suggesting that these earlier data were adversely affected by experimental problems, surface films and/or IR drop. The energy of activation for the couple was determined to be 56 kJ mol^–1. The temperature dependence of the LiAl|Li⁺ couple is also discussed.