Enhanced performance of Ni‐MOFs‐based O3‐type NaNi _0.5 Mn _0.5 O ₂ cathode material for sodium‐ion batteries

Abstract One prominent cathode material utilized in commercial sodium‐ion batteries is the O3‐type NaNi 0.5 Mn 0.5 O 2 . The application of this material is hindered by multistage phase transitions and insufficient air stability. In this study, an innovative O3‐type NaNi 0.5 Mn 0.5 O 2 , derived from Ni‐MOFs (referred to as M‐NNMO), has been developed as a cathode material for sodium‐ion batteries. The M‐NNMO cathode exhibits a discharge specific capacity of 124 mAh·g −1 at a rate of 0.1C within 2.0 to 4.0 V. Furthermore, this material demonstrates an impressive capacity retention of 75% after undergoing 100 cycles. Complex phase transitions can be inhibited and ion diffusion rates can be increased simultaneously by Ni‐MOFs through the enhancement of transition metal–oxygen bonding and the rise in Na layer gap, which are in charge of the remarkable performance improvement. Importantly, the enhanced stability of the M‐NNMO transition metal layer based on the unique structural properties of Ni‐MOFs in air stability tests. This work will provide theoretical guidance to design sodium‐ion battery cathode materials with superior performance.