Theoretical prediction of LiScO2 nanosheets as a cathode material for Li–O2 batteries

Abstract

Our previous study (J. Mater. Chem. A, 2018, 6, 3171-3180) theoretically predicted that a scandium oxide (ScO₂) monolayer can deliver high specific capacity and energy density as the active material of a lithium-ion (Li-ion) battery, but the voltage will drop below 0.5 V when ScO₂ is lithiated to LiScO₂ during the discharge process. The current study predicts that the discharge product LiScO₂ in the Li-ion battery mode can potentially work as the host material of Li–O₂ batteries. It is found that the adsorption of O₂ on the LiScO₂ substrate is energetically favored. The LiScO₂ substrate can also provide strong affinities to molecular LiO₂ and Li₂O₂ species. It is interesting to find that the presence of an O₂ molecule can oxidize the pre-adsorbed Li₂O₂ molecule and result in two LiO₂ molecules. Hence, the final discharge product of the Li–O₂ battery using the LiScO₂ cathode is expected to be a crystalline-like LiO₂ layer. The discharge voltage related to forming a LiO₂ layer on the LiScO₂ substrate is 3.50 V vs. Li⁺/Li according to the present theoretical calculation.