Towards Synergistic Electrode–Electrolyte Design Principles for Nonaqueous Li–O₂ batteries

Abstract

One route toward sustainable land and aerial transportation is based on electrified vehicles. To enable electrification in transportation, there is a need for high-energy-density batteries, and this has led to an enormous interest in lithium–oxygen batteries. Several critical challenges remain with respect to realizing a practical lithium–oxygen battery. In this article, we present a detailed overview of theoretical efforts to formulate design principles for identifying stable electrolytes and electrodes with the desired functionality and stability. We discuss design principles relating to electrolytes and the additional stability challenges that arise at the cathode–electrolyte interface. Based on a thermodynamic analysis, we discuss two important requirements for the cathode: the ability to nucleate the desired discharge product, Li₂O₂, and the ability to selectively activate only this discharge product while suppressing lithium oxide, the undesired secondary discharge product. We propose preliminary guidelines for determining the chemical stability of the electrode and illustrate the challenge associated with electrode selection using the examples of carbon cathodes and transition metals. We believe that a synergistic design framework for identifying electrolyte–electrode formulations is needed to realize a practical Li–O₂ battery.