Ni-rich cathode materials can deliver higher energy density with a lower cost compared with other conventional layered oxide materials. However, the cycling performance of Ni-rich materials needs further improvement, and the irreversible phase transformation related to the cell failure is not fully understood yet. Although an H1H2H3 structural change process is revealed, a more specific explanation about the difference of these hexagonal phases is needed for deeper comprehension and further targeted modification of Ni-rich materials. In this work, the different phase transformation mechanisms of LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) and LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) are investigated by C X-ray diffraction (XRD) measurement, and the relationship between structural change and capacity degradation is discussed, showing that H3 phase can be harmful for cycling. In addition, ⁶Li solid state nuclear magnetic resonance (ss-NMR) experiments are carried out for detecting the Li chemical environment at different state of charge, and the data can be associated with structural change obtained from in operando XRD results. From the analysis mentioned above, a new explanation of H1/H2/H3 is given, and a relationship between long range and local structural change has been put forward for the first time.

与其他传统的分层氧化物材料相比，富镍阴极材料可以以较低的成本提供更高的能量密度。然而，富镍材料的循环性能需要进一步改善，并且与电池失效有关的不可逆相变还没有被完全理解。尽管揭示了H1 H2 H3的结构变化过程，但需要更具体的解释以了解这些六方相的差异，以便更深入地理解和进一步针对富镍材料进行有针对性的改性。在这项工作中，LiNi _0.6 Co _0.2 Mn _0.2 O ₂（NCM622）和LiNi _0.8 Co _0.1 Mn的不同相变机理通过C X射线衍射（XRD）测量研究了_0.1 O ₂（NCM811），并讨论了结构变化与容量退化之间的关系，表明H3相可能对循环有害。此外，还进行了^6次Li固态核磁共振（ss-NMR）实验，以检测不同荷电状态下的Li化学环境，并且该数据可以与从操作XRD结果获得的结构变化相关联。通过上述分析，给出了H1 / H2 / H3的新解释，并且首次提出了长程与局部结构变化之间的关系。