Storage Failure Mechanisms and Modifications of Ni‐Rich Cathode Materials: From Polycrystalline to Single‐Crystal Forms†

Comprehensive Summary Ni‐rich cathode materials, exemplified by LiNi 1– x – y Co x MnyO 2 (NCM), have significantly propelled Li‐ion battery (LIB) technology forward owing to their high energy density. However, the long‐term storage stability of these materials remains a critical challenge that must be addressed. This review provides a comprehensive analysis of the storage failure mechanisms in both polycrystalline (PC‐NCM) and single crystal (SC‐NCM) forms, a topic that has been seldom reviewed. It delves into the microstructural changes and performance degradation that occur during storage, emphasizing the effects of environmental factors on NCM materials, including the formation of surface impurities and structural deterioration. Additionally, the review discusses various enhancement strategies, such as surface coatings, doping, and gas treatments, which are designed to improve storage stability. Furthermore, the review projects insights from current polycrystalline studies to suggest future research directions aimed at enhancing the air stability of SC‐NCM, which is vital for improving the safety and durability of LIBs. Key Scientists