Density Functional Theory Based Study of the Electron Transfer Reaction at the Lithium Metal Anode in a Lithium–Air Battery with Ionic Liquid Electrolytes

Abstract

Room temperature ionic liquids, which have unique properties such as a relatively wide electrochemical stability window and negligible vapor pressure, are promising candidates as electrolytes for developing lithium–air batteries with enhanced performance. The local current density, a crucial parameter in determining the performance of lithium–air batteries, is directly proportional to the rate constant of the electron transfer reaction at the surface of the anode that involves the oxidation of pure lithium metal into lithium ion (Li+). The electrochemical properties of ionic liquid based electrolytes, which can be molecularly tailored on the basis of the structure of their constituent cations and anions, play a crucial role in determining the reaction rate at the anode. In this paper, we present a novel approach, based on Marcus theory, to evaluate the effect of varying length of the alkyl side chain of model imidazolium based cations on the rates of electron transfer reaction at the anode. Density functi...