Corrosion of Lithium in Alkaline Solution

The corrosion of Li was studied in 3-5M LiOH at 25/sup 0/C and in 4.5M LiOH at 4/sup 0/-60/sup 0/C. The Arrhenius relationship is obeyed and the apparent activation energy for the Li corrosion reaction is found to be 15.5 kcal mole/sup -1/. An empirical relationship is derived from which the corrosion rate, v/sub f/, can be obtained at any molar LiOH. At 25/sup 0/C v/sub f/(kA m/sup -2/) = 0.31(54.1 - 10(LiOH)). An equation is also given which allows calculation of the Li corrosion rate when the metal is anodically polarized. The kinetics of the H/sub 2/ evolution reaction (e.r.) on Li were determined, the transfer coefficient ..cap alpha.. has a value of 0.14. The rate-controlling process of the Li dissolution reaction is the highly polarized H/sub 2/ evolution at cathodic sites. Based on the ..cap alpha.. value obtained, the enthalpy of activation for the H/sub 2/ e.r. on Li at OCV is calculated to be 22.8 kcal mole/sup -1/. It is proposed that the protective film on Li has a duplex structure with a thin oxide/hydroxide layer adjacent to the metal and an outer porous hydrated layer through which the reaction products and reactants can pass freely. 7more » figures.« less