O3-NaNi0.47Zn0.03Mn0.5O2 cathode material for durable Na-ion batteries

Highlights: • O3-NaNi_0.47Zn_0.03Mn_0.5O₂ material with excellent electrochemical reversibility is obtained by doping with zinc cations. • NaNi_0.47Zn_0.03Mn_0.5O₂ cathode shows an excellent capacity retention of 80% within 150 cycles at 0.5 C at 2–4 V. • After the introduction of Zn²⁺, the phase change above 4 V was suppressed. • When exposed to air, NNZMO sample still showed significantly better electrochemical performance than NNMO. -- Abstract: O3-type transition metal oxides as the cathodes for Na-ion batteries have attracted extensive attention owing to their high theoretical specific capacity and ease of synthesis. This work indicates enhanced electrochemical reversibility and improved air stability via a rational Zn²⁺ doping for O3-NaNi_0.5Mn_0.5O₂. It exhibits a discharge capacity of 113 mAh g⁻¹ at 0.5 C, excellent capacity retention of 80% after 150 cycles, and the capability to release a capacity of 82 mAh g⁻¹ at 5 C in the voltage range of 2–4 V. The doped cathode undergoes a phase transition of O3-O3/O′3-P3-P′3-O''3 with a small volume change of approximately 2.00% in the voltage range of 2–4 V, and a subsequent slight structural change in the high voltage range of 4–4.2 V, which well demonstrates the enhanced cyclic stability. The assembled full cell confirms the feasibility of applying O3-type NaNi_0.47Zn_0.03Mn_0.5O₂ cathode for Na-ion batteries. Thus, the work suggests an efficient strategy to better release the potential of high-energy cathode for Na-ion batteries.