Probe the Role of Oxygen Anionic Redox in High‐Energy‐Density Battery with Advanced Characterization Techniques

Abstract The rapid advancement of the new energy industry has resulted in an urgent demand for batteries with superior energy density. To this end, oxygen anionic redox (OAR) emerges as a new paradigm for significantly enhancing battery energy density, which is initially explored in diverse battery systems. Although the feasibility of OAR in various cathode materials is affirmed, it is essential to consider the inevitable consequent issues, such as the irreversibility of OAR process and potential damage to electrode structure. To achieve a comprehensive understanding and effectively leverage the potential of OAR for high‐energy‐density batteries, extensive research has focused on the performance enhancement and failure mechanisms of OAR in different battery systems. However, owing to the limitation of the characterization techniques, a systematic and comprehensive research approaches for studying OAR is lacking. Herein, combing the advanced characterization techniques, an overview is provided from local OAR to full OAR in different cathodes, in which the triggers, working processes and challenges associated with OAR are presented. This perspective will end with a discussion on how to develop the advanced characterization technology applied for OAR along with a caution of practical application for OAR.