Dynamic oxygen shield eliminates cathode degradation in lithium–oxygen batteries†
Realizing a reversible and long-life nonaqueous lithium–oxygen (Li–O2) battery has been proven extremely challenging due to reactive reaction products/intermediates that rapidly corrode and passivate the cathode. In this work, we effectively protect the cathode from oxygenated side reactions by manipulating the fluxes of reduced discharge mediator (rDM) and O2, thereby creating a steady-state rDM-rich region which completely covers the cathode. This rDM-rich region acts as a dynamic O2 shield and isolates the cathode from oxygen reactions. We demonstrate that this strategy eliminates 98% of the by-products on the cathode, achieving a more than 10-fold increase in cycle life compared to conventional dual-mediator cells. A diffusion-reaction model is developed to assist understanding of the system and to guide future design. This work demonstrates an effective approach to achieve degradation-free cathodes for efficient and long-life Li–O2 batteries.