Polymeric redox mediator as a stable cathode catalyst for lithium-O_2 batteries

摘要

Lithium-oxygen (Li-O-2) 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-O-2 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 mu A 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-O-2 batteries with improved performance.