Capturing O ₂ ^•‒ Intermediate to Promote Oxygen‐Reduction‐Reaction Pathway for Li‐O ₂ Batteries with High‐Areal‐Capacity

Abstract

ABSTRACT Oxygen reduction reaction (ORR) with two‐electron transfer pathway is the key reaction for aprotic lithium‐oxygen (Li‐O 2 ) batteries with high theoretical energy density. Herein, we present that capturing ORR superoxide (O 2 •‒ ) intermediate can promote ORR rate and stability by using pyrrolidinium bis(trifluoromethanesulfonyl)imide (Py‐TFSI). Py + cation can bind O 2 •‒ absorbed on the surface of solid catalyst and transfer it into electrolyte, in which the coordination chemistry not only inhibits the generation and disproportionation of LiO 2 on the electrode surface to enhance ORR rate, but also stabilize O 2 •‒ to inhibit its related side reactions for better ORR stability. Over fivefold enhancement of ORR activity is observed. Moreover, Py‐TFSI promotes the uniform lithium deposition through enriching inorganics in solid‐electrolyte‐interphase and electrostatic shielding effect on Li metal surface, resulting in 2.5 times increase of cycling stability of Li electrode. As a result, the Li‐O 2 batteries demonstrate a cycle lifespan of 47 days with a high areal capacity of 5 mAh cm ‒2 . This study presents the deep understanding of intermediate manipulation mechanism for ORR and provides the effective way to improve the performance of metal‐O 2 batteries.