A room temperature rechargeable Li 2 O-based lithium-air battery enabled by a solid electrolyte.

A lithium-air battery based on lithium oxide (Li 2 O) formation can theoretically deliver an energy density that is comparable to that of gasoline. Lithium oxide formation involves a four-electron reaction that is more difficult to achieve than the one- and two-electron reaction processes that result in lithium superoxide (LiO 2 ) and lithium peroxide (Li 2 O 2 ), respectively. By using a composite polymer electrolyte based on Li 10 GeP 2 S 12 nanoparticles embedded in a modified polyethylene oxide polymer matrix, we found that Li 2 O is the main product in a room temperature solid-state lithium-air battery. The battery is rechargeable for 1000 cycles with a low polarization gap and can operate at high rates. The four-electron reaction is enabled by a mixed ion-electron-conducting discharge product and its interface with air.