Improving the Performance of Layered Oxide Cathode Materials with Football‐Like Hierarchical Structure for Na‐Ion Batteries by Incorporating Mg2+ into Vacancies in Na‐Ion Layers

Abstract The development of advanced cathode materials is still a great interest for sodium‐ion batteries. The feasible commercialization of sodium‐ion batteries relies on the design and exploitation of suitable electrode materials. This study offers a new insight into material design to exploit high‐performance P2‐type cathode materials for sodium‐ion batteries. The incorporation of Mg 2+ into intrinsic Na + vacancies in Na‐ion layers can lead to a high‐performance P2‐type cathode material for sodium‐ion batteries. The materials prepared by the coprecipitation approach show a well‐defined morphology of secondary football‐like hierarchical structures. Neutron power diffraction and refinement results demonstrate that the incorporation of Mg 2+ into intrinsic vacancies can enlarge the space for Na‐ion diffusion, which can increase the d‐spacing of the (0 0 2) peak and the size of slabs but reduce the chemical bond length to result in an enhanced rate capability and cycling stability. The incorporation of Mg 2+ into available vacancies and a unique morphology make Na 0.7 Mg 0.05 Mn 0.8 Ni 0.1 Co 0.1 O 2 a promising cathode, which can be charged and discharged at an ultra‐high current density of 2000 mA g −1 with an excellent specific capacity of 60 mAh g −1 . This work provides a new insight into the design of electrode materials for sodium‐ion batteries.