Polymeric redox mediator as a stable cathode catalyst for lithium-O2 batteries

Lithium-oxygen (Li–O2) batteries are attractive as a next-generation power source because of their high theoretical energy density of 3436 Wh L−1. However, Li2O2 formed on a cathode during discharging can be accumulated on the electrode surface, followed by an irreversible decomposition of Li2O2 during charging, deteriorating the cycling performance of Li–O2 batteries. In this study, we prepare a polymeric redox mediator (PRM) as a cathode catalyst consisting of iodine and polyvinylidene fluoride (PVDF). In the PRM, iodine is chemically combined in the end of PVDF. Among these PRM catalysts, PRM-100 with an optimal ratio of Iodine to PVDF exhibits cycling increased by 214.0% and 925% and polarization decreased by 53.7% and 24.7% at 100 and 500 μA cm−2, respectively, compared to the sample prepared in the absence of iodine. Thus, the PRM consisting of a redox mediator and polymer matrix can be a promising candidate to be a cathode catalyst for Li–O2 batteries with improved performance.