American Chemical Society
Browse

Direct In Situ Spectroscopic Evidence for Solution-Mediated Oxygen Reduction Reaction Intermediates in Aprotic Lithium–Oxygen Batteries

Download (598.38 kB)
journal contribution
posted on 2021-12-28, 20:44 authored by Zhiwei Zhao, Xu Zhang, Zhen Zhou, Erkang Wang, Zhangquan Peng
A fundamental understanding of the reaction process is essential to predict and enhance the performance of electrochemical devices. As a central reaction in aprotic lithium–oxygen (Li–O2) batteries, the oxygen reduction reaction (ORR) has been confronted with the “sudden-death” phenomenon caused by the cathode passivation from discharge product Li2O2. The soluble catalyst (e.g., reduction mediator) promoted solution-mediated ORR represents an elegant solution. However, no direct molecular evidence is available so far, and its link to Li–O2 batteries performance remains hypothetical. Here, we present in situ surface-enhanced Raman spectroscopy and obtain direct spectroscopic evidence (i.e., LiAQ and LiAQO2) of the solution-mediated ORR on a model anthraquinone (AQ, a typical reduction mediator)-immobilized Au electrode. With the assistance of density functional theory calculations and differential electrochemical mass spectrometry, the related elementary reaction steps of the solution-mediated ORR are proposed. This work provides intuitive insights into the AQ-catalyzed solution-mediated ORR mechanism that is helpful in the optimization and tailor-design of soluble catalysts for excellent next-generation Li–O2 batteries.

History