Computational Understandings of Cation Configuration-Dependent Redox Activity and Oxygen Dimerization in Lithium-Rich Manganese-Based Layered Cathodes

Lithium-richmanganese-based layered oxides have emerged as a freshparadigm for developing advanced cathode materials with high energydensity for next-generation lithium-ion batteries. Understanding latticeoxygen dimerization is quite essential for the optimal design of lithium-richmanganese-based cathode materials. Herein, based on density functionaltheory (DFT) calculations, a local Ni-honeycomb Li-Ni-Mncation configuration for the Li1.22Ni0.22Mn0.56O2 cathode was carefully examined, which maycoexist with the well-known local Li-honeycomb structure in experimentallysynthesized Li1.2Ni0.2Mn0.6O2 samples. The local Li-Ni-Mn cation configurationshave significant impacts on oxygen redox activity, transition metalatom migration, and oxygen dimerization in the charging process ofLi( x )Ni(0.22)Mn(0.56)O(2). It is found that there is no correlation between high latticeoxygen redox activity and easy oxygen dimerization, such as Li-honeycombstructures simultaneously exhibiting higher oxygen redox activitiesand higher activation energy barriers for prohibiting oxygen dimerizationthan Ni-honeycomb structures. The structural regulations of the localLi-Ni-Mn cation configuration by avoiding the localNi-honeycomb structures to inhibit Mn migration and ease lattice oxygendimerization and by making full use of the local Li-honeycomb structureswould maximize performance of Li-rich Mn-based layered oxides. Suchfresh insights provide us a fresh strategy to optimally design thelocal honeycomb structure for high-performance Li-rich Mn-based cathodematerials.