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: Li2 O3 , 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 Li2 O3 inherits the local arrangements from ambient LiO2 and Li2 O2 phases. These novel lithium oxides beyond the ambient Li2 O, Li2 O2 , and LiO2 phases show great potential in improving battery design and performance in large battery applications under extreme conditions.