Effect of the Calcination Temperature on the Morphology, Structure, and Electrochemical Properties of Na_0.67Ni_0.11Cu_0.11Fe_0.3Mn_0.48O₂ Nanoparticles as Cathode Material for Na Batteries

Layered Na–Fe–Mn-based cathode materials Na 0.67 Ni 0.11 Cu 0.11 Fe 0.3 Mn 0.48 O 2 (NCFM) for sodium-ion batteries are prepared by a spray drying method in this report. The effect of calcination temperature on NCFM’s morphology, structure, and electrochemical properties is investigated in detail. The results show that with the rising temperature from 700 to 900 °C, the proportion of the P2 phase in the as-prepared material gradually increases, the pure P2 phase appears at 900 °C, the particle size increases from the nanoscale to microscale, and the lamellar morphology becomes more obvious. The nanoscale flake-like sample obtained at 750 °C (NCFM-750) exhibits the initial discharge specific capacities of 160.3, 109.9, 105.2, and 102.6 mAh g –1 at 0.1 C, with the capacity retentions of 68.8, 85.3, 84.9, and 84.4% after 300 cycles at 0.2 C under the temperatures of 25, 0, −10, and −20 °C, respectively.