Atomistic and first principles: Computational studies of LiO₂ batteries

In this chapter we review first-principles computational work on lithium air batteries. Density functional calculations on Li₂O₂ nanoparticles, surfaces, and bulk are beginning to provide an understanding of the mechanisms of Li₂O₂ electrochemical growth and dissolution. It has been predicted that oxygen-rich surfaces of Li₂O₂ play a role in controlling the oxygen evolution reaction (OER) overpotential and that conductivity and hence current densities are limited by the particle morphology and defects. Similarly, density functional calculations have provided some understanding of the role of the electrocatalysts in facilitating Li-O₂ reactions. For carbon, oxidized defect sites are key for catalyzing the Li-O₂ reaction, whereas for noble metals, Pt and Pd are favored. Transition metal oxides such as MnO₂ can act as dual-purpose lithium and lithium-oxide incorporating structures, facilitating the reduction and oxidation of O₂/O₂ ^- when lithiated. Finally, computational work on electrolytes highlights the need for electrolytes that are stable in the presence of reactive peroxide and superoxide species.