Dissociation of (LiO) on graphene and boron-doped graphene: insights from first-principles calculations.

Reducing charge overpotential is of great significance to enhance the efficiency and cyclability of Li-O batteries. Here, a dramatically reduced charge overpotential via boron-doped graphene as a catalytic substrate is successfully predicted. By first-principles calculations, from the perspective of reaction thermodynamics and kinetics, the results show that the electrochemical oxidation of the LiO cation is easier than the chemical oxidation of the neutral LiO molecule, and the oxidation of (LiO) is facilitated by boron-doping in pristine graphene. More importantly, the results reveal the oxidation mechanism of (LiO): two-step dissociation with the LiO molecule as a reactive intermediate has advantages over one-step dissociation; the rate-determining step for the dissociation of (LiO) is the oxygen evolution process, while the lithium removal process is the rate-determining step for the dissociation of (LiO), (LiO), and (LiO).