Safe Lithium‐Metal Anodes for Li−O2 Batteries: From Fundamental Chemistry to Advanced Characterization and Effective Protection

Abstract Rechargeable Li−O 2 batteries play an increasing important role as energy storage devices, which have both, a high capacity anode and a cathode using an inexhaustible resource. As a key component in Li−O 2 batteries, the Li‐metal anode suffers from major drawbacks related to Li dendrite formation and SEI layer growth, which are also major issues for Li‐metal rechargeable batteries. This review presents an overview on the scientific challenges, fundamental mechanisms and modification strategies of Li‐metal anodes for Li−O 2 batteries. Firstly, basic principles and challenges on Li‐metal anodes are briefly retrospected. We further summarize and categorize the prevailing characterization techniques based on Li dendrite morphology characterization and SEI composition analysis. The up‐to‐date development of in‐situ and operando characterization is also included. Following the obtained insights, effective protection/modification strategies towards practical application for Li−O 2 batteries are presented. Furthermore, we highlight the significance of advanced characterization techniques in interrogating the buried keys for solving practical hindrances for Li−O 2 batteries. The comprehensive characterization and analysis of Li anodes, cathodes, and electrolytes by various methods together with the development of novel techniques are expected to be indispensable to gain a thorough understanding of the battery operation and for offering guidelines for their practical development.