富锂锰基正极材料反应机理研究进展

富锂锰基正极材料xLi₂MnO₃·（1-x）LiMO₂（M=Ni，Co或Mn）具有比容量高（≥250 mA·h/g）和成本低的显著优势，近年来受到学术界和工业界的广泛关注。但是，关于材料的结构和反应机理等问题一直存在着一些争议。对富锂锰基材料的结构和反应机理进行了总结和评述。对材料的结构总结了单相固溶体、两相混和物、局部阳离子有序排列3种观点，通过分析发现富锂锰基材料的结构与元素的比例、制备条件等密切相关。反应机理重点阐述了材料的Li⁺/H⁺交换理论、阴离子氧氧化还原机理（阴离子电荷补偿理论）和Mn⁴⁺/Mn⁷⁺反应机理假说，并对阴离子氧氧化还原反应过程的中间产物是否存在O—O二聚体或者氧空穴进行了讨论分析。最后，对这类材料未来的产品化应用方向提出了展望，混掺使用可能是富锂锰基材料产业化的切入点，高性价比的富锂锰基材料的产业化应用将再一次推动锂离子电池发展迈向一个新台阶。

Research progress of reaction mechanism of lithium-rich manganese-based cathode materials

The lithium-rich manganese-based cathode material of xLi₂MnO₃·（1-x）LiMO₂（M=Ni，Co or Mn） has a high specific capacity（≥250 mA·h/g） and the significant advantages of low cost.In recent years，it has also received widespread attention from academia and industry.There are still some controversies about material structure and reaction mechanism.The structure and reaction mechanism of lithium-rich manganese-based materials were summarized and reviewed.Three viewpoints of materials structure were summarized：single-phase solid solution，two-phase mixture，and local cation ordered arrangement.It was concluded that the structure of lithium-rich manganese-based materials was closely related to the element ratio，preparation conditions and so on.The reaction mechanism was focused on the Li⁺/H⁺ exchange theory，anionic oxygen redox（anion charge compensation theory） and Mn⁴⁺/Mn⁷⁺ reaction mechanism hypothesis.The existence of O—O dimer or oxygen hole in the intermediate products of the anionic oxygen redox reaction process was discussed and analyzed.Finally，some thoughts on the future product application direction of this kind of materials were put forward.Mixing with other cathode materials may open the door of industrialization of lithium-rich manganese-based materials，and the industrial application of cost-effective lithium-rich manganese-based materials will promote the development of lithium-ion batteries to a new level.