碳纳米管增强纳米硫酸铁钠正极材料性能OA

Polyanionic sodium iron sulfate(Na2Fe(SO4)2)cathode material for sodium-ion batteries offers advantages of high theoretical capacity and structural stability.However,its low intrinsic electronic conductivity limits both electrochemical performance and large-scale application.To enhance conductivity,we proposed constructing a three-dimensional continuous conductive network by incorporating highly conductive carbon nanotubes(CNTs),thereby improving the material's electrochemical performance.A two-step synthesis strategy combining sol-gel preparation with high-temperature calcination was employed to synthesize pure-phase Na2Fe(SO4)2.Through ultrasonic-assisted liquid-phase mixing and subsequent processing,CNTs were uniformly attached to the surface of Na2Fe(SO4)2 particles,forming Na2Fe(SO4)2/CNTs composites.XRD analysis indicated that the composite material retained the pure-phase Na2Fe(SO4)2 structure,with CNTs not altering its phase purity.The incorporation of CNTs into the Na2Fe(SO4)2/CNTs composite significantly enhanced its electronic conductivity and structural stability.SEM analysis following cycling demonstrated that the CNTs network alleviated volumetric stress during charging and discharging,thereby preserving particle integrity and substantially improving electrochemical performance.Conductivity testing showed the composite material's conductivity enhanced to the 10-3 S/cm range,representing at least a six-order-of-magnitude improvement over the pure-phase material.Electrochemical testing revealed that the initial discharge specific capacity of the pure-phase material was only 67.06 mAh/g,whereas the composite material achieve a first-cycle capacity of 78.73 mAh/g,demonstrating excellent rate capability(67.31 mAh/g at 5 C)and long-term cycling stability(78.7％capacity retention after 100 cycles within the 2～4.5 V voltage window).