Exploring the LiOH Formation Reaction Mechanism in Lithium–Air Batteries

Identifying the electronic factors that enhance or hinder the formation of primary discharge/charge products or secondary parasitic species is crucial for defining the fundamental chemical reactions that may take place within the complex electrolytic media of a lithium–air battery. For example, several reaction mechanisms have been proposed to explain the formation of the LiOH discharge product in the presence of LiI and water; however, none of these have been demonstrated or fully understood. A similar situation exists for the decomposition reaction, which leads toward molecular oxygen evolution. Herein we present a mechanistic theoretical study of the reactions taking place in the electrolytic media of a Li–O2 battery with dimethoxyethane (DME) in the presence of both water and the LiI additive. The results reveal that water is the most energetically favorable source of protons yielding LiOH. The effect of iodide in lithium peroxide bond scission can be ascribed to a halogen-bond interaction. The reaction pathway involving hydrogen peroxide was found to be a viable route accounting for the lithium hydroxide decomposition.