博士生任梦豪论文"Thermal Decomposition Mechanisms and Inherent Stability Differences Between O2- and O3-Lithium-Rich Manganese-Based Oxide Cathodes"被Advanced Functional Materials接收发表
发布时间：2025-12-07
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Lithium-rich manganese oxides with an O2-type structural framework (O2-LRMO) promise to exhibit highly reversible electrochemical behavior and suppressed voltage decay for use in high-energy-density lithium ion batteries. However, how the oxygen layer stacking govern their phase evolution and thermal stability remains elusive. Herein, we investigate the thermal decomposition mechanism of O2- and O3-LixLi0.17Ni0.133Co0.133Mn0.564O2 (x=0.39, 0.78) at evaluated temperatures. Combined with in-situ time-resolved synchrotron X-ray diffraction and thermal analysis, it reveals that O2-LRMO, owing to its unique ABAC oxygen layer arrangement, follows a two-step thermal failure path. Specifically, the phase transformation from metastable O2 to an intermediate O3 at the initial heating process, and followed by the formation of spinel phase, with both steps accompanied by O2 release. Noteworthily, the newly formed intermediate O3 phase delays the formation of the spinel phase compared to that of pure O3-LRMO. O2-LRMO and O3-LRMO exhibit comparable thermal release behavior upon incorporation of the electrolyte, despite significant inherent stability differences, which indicates surface reactions rather than oxygen evolution act as the dominant factor in thermal runaway. Overall, these findings provide an important theoretical basis for optimizing the thermal stability and electrochemical performance of O2-type lithium-rich manganese-based cathode materials in the future.