Oxygen-Rich Lithium Oxide Phases Formed at High Pressure for Potential Lithium-Air Battery Electrode

The lithium-air battery has great potential of achieving specific energy density comparable to that of gasoline. Several lithium oxide phases involved in the charge-discharge process greatly affect the overall performance of lithium-air batteries. One of the key issues is linked to the environmental oxygen-rich conditions during battery cycling. Here, the theoretical prediction and experimental confirmation of new stable oxygen-rich lithium oxides under high pressure conditions are reported. Three new high pressure oxide phases that form at high temperature and pressure are identified: Li₂O₃, LiO₂, and LiO₄. The LiO₂ and LiO₄ consist of a lithium layer sandwiched by an oxygen ring structure inherited from high pressure ε-O₈ phase, while Li₂O₃ inherits the local arrangements from ambient LiO₂ and Li₂O₂ phases. These novel lithium oxides beyond the ambient Li₂O, Li₂O₂, and LiO₂ phases show great potential in improving battery design and performance in large battery applications under extreme conditions.