Microwave Hydrothermal Synthesis of NaNi1/3Fe1/3Mn1/3O2 and Its Performance in Sodium Ion Batteries

Global energy storage resources are facing shortages, while market demand continues to grow rapidly. The abundance of sodium resources and the low cost of sodium salts make sodium-ion batteries a promising candidate for large-scale energy storage applications. Among various cathode materials, layered transition metal oxides have attracted significant attention due to their structural advantages. However, these materials often suffer from transition metal layer sliding during sodium extraction and insertion, leading to limited capacity, poor phase transition stability, and restricted practical application. This study systematically investigates the application of microwave-assisted synthesis in the preparation of sodium-ion battery cathode materials. Through comparative experiments, the unique advantages of microwave-assisted synthesis in optimizing structure and performance are revealed. Focusing on the nickel-iron-manganese ternary layered oxide NaNi₁/₃Fe₁/₃Mn₁/₃O₂ (NFM) as a cathode material for sodium-ion batteries, NFM prepared by microwave-assisted hydrothermal method was compared with that synthesized by conventional hydrothermal method. The results indicate that the microwave-assisted hydrothermal method produces NFM with superior microscopic morphological characteristics, more uniform grain size, and significantly improved geometric regularity of the hexagonal crystal structure. This material exhibits excellent electrochemical performance, with an initial discharge capacity of 96.24 mAh g-1 at 1C current density and a capacity retention of 88.67 mAh g-1 after 150 cycles. By adjusting the synthesis temperature and PH, the optimal conditions for microwave-assisted synthesis were determined to be 170°C and PH=10. The NFM material prepared under these conditions demonstrates high crystallinity, uniform nano-morphology, and excellent sodium-ion diffusion kinetics, achieving an initial discharge capacity of 100.4 mAh/g (1C), indicating strong application potential.