Advances in modeling and simulation of Li–air batteries

Abstract

Li–air batteries have potential to be the next generation power sources for various applications, from portable devices to electric vehicles and microgrids, due largely to their significantly higher theoretical energy densities than those of the existing batteries. The commercialization of this technology, however, is hindered by a variety of technical hurdles, including low obtainable capacity, poor energy efficiency, and limited cycle life. Breakthrough to these barriers requires a fundamental understanding of the complex electrochemical and transport behaviors inside the batteries. Mathematical modeling and simulation are imperative in gaining important insight into the mechanisms of these complex phenomena, which is vital to achieving rational designs of better materials for high-performance batteries. In this paper, we present a comprehensive review of the latest advances in modeling and simulation of Li–air batteries and offer our perspectives on new directions of future development. Unlike previous reviews that centered mainly on continuum modeling of non-aqueous Li–air batteries, the present paper focuses on mathematical descriptions of the detailed transport and electrochemical processes in different types of Li–air batteries. We start with a brief introduction to the working principles of Li–air batteries. Then, the governing equations for mass transport and electrochemical reactions in non-aqueous Li–air batteries are formulated, including lithium ion and oxygen transport in the porous air electrode, the formation of solid discharge products, the kinetics of electrode reactions, the evolution of electrode structure, the distribution of active sites, the effect of the side reactions during cycling, the phenomena of the volume change, and the charge process. In addition, the mo\deling and simulations of aqueous and hybrid Li–air batteries are reviewed, highlighting the phenomena that are different from those in the non-aqueous ones. Finally, the challenges facing the modeling and simulation of Li–air batteries are discussed and perspectives for the development of a new generation of Li–air batteries are outlined.