Oxygen Electrode Rechargeability in an Ionic Liquid for the Li–Air Battery

Oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) on glassy carbon (GC) and gold electrodes were investigated in a neat and Li + -containing room-temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium bis(triflouromethanesulfonyl)imide (EMITFSI). The presence of Li + significantly changes the ORR mechanism. While similar one-electron O 2 /O 2 •– reversible couples result on both electrodes in neat EMITFSI, in the presence of added LiTFSI, the initially formed LiO 2 decomposes to Li 2 O 2 . In addition, the ORR and OER in the Li + -doped solution exhibit strong distinctions between the Au and GC electrodes. The voltammetric data on the Au electrode revealed a highly rechargeable ORR, yielding LiO 2 and Li 2 O 2, which underwent multiple cycles without electrode passivation.