Advances and Challenges for Aprotic Lithium‐Oxygen Batteries using Redox Mediators

Rechargeable aprotic Li−O 2 batteries that can deliver extremely high energy density have attracted worldwide attention. However, the practical use of this promising technology is hindered by an unsatisfactory cycling life and inferior energy efficiency (high discharge/charge voltage gap), although significant progress has been made in this area in the last decade. Recent reports indicate that soluble catalysts or redox mediators dissolved in aprotic electrolytes can catalyze Li 2 O 2 decomposition and reduce the voltage gap between O 2 reduction reaction and O 2 evolution reaction. Here, a specific review on a series of suitable soluble catalysts for Li−O 2 batteries is provided. This review will highlight the underpinning chemistry and electrochemistry mechanisms of Li−O 2 batteries, as well as the recent progress and challenges of soluble catalysts, with the aim of motivating researchers to further explore applications in Li−O 2 cells and other energy storage and conversion systems.