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 O2/O2 •– reversible couples result on both electrodes in neat EMITFSI, in the presence of added LiTFSI, the initially formed LiO2 decomposes to Li2O2. 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 LiO2 and Li2O2, which underwent multiple cycles without electrode passivation.