Inhibition of Discharge Side Reaction by Promoting Solution-Mediated Oxygen Reduction Reaction with Stable Quinone in Li-O2 Batteries

Aprotic lithium-oxygen (Li-O2) batteries with an ultrahigh theoretical energy density have great potential in rechargeable power supply, while their application still faces several challenges, especially poor cycle stability. To solve the problems, one of effective strategies is to inhibit the generation of LiO2 intermediate produced via surface-mediated oxygen reduction reaction (ORR) pathway, which is an important species inducing the byproduct generation and low cell cyclic stability. Herein, a series of quinones and solid materials serve as the solution-mediated and surface-mediated ORR catalysts, and it was found that the generation of LiO2 and byproducts from solid catalysts was inhibited by quinones. Among the studied quinones, benzo[1,2-b:4,5-b']dithiophene-4,8-dione (BDTD), a quinone molecule with the advantage of highly symmetrical planar and conjugated structure and without α-H, shows high redox potential, diffusion coefficient and electrochemical stability, and consequently the best ORR activi...