纳米多孔Fe_2O_3–Fe_3O_4/Ni复合材料作为锂离子电池负极材料的电化学性能

Electrochemical performance of nanoporous Fe_2O_3–Fe_3O_4/Ni composite as negative electrode material for lithium ion batteries

通过在NH4F+H2O的乙二醇溶液中阳极氧化铁箔,制备了纳米多孔结构的铁氧化物(Fe2O3–Fe3O4),然后在纳米多孔中电沉积镍,再经过400°C退火0.5 h,获得了镍与纳米多孔氧化铁的复合材料(Fe2O3–Fe3O4/Ni)。考察了电流密度和时间对镍沉积的影响。用扫描电镜、能谱仪、X射线衍射仪表征了复合材料的表面形貌、元素组成和物相,测试了其电化学性能并与未经电沉积镍的纳米多孔氧化铁(Fe2O3–Fe3O4)比较。结果表明,氧化铁由Fe2O3和Fe3O4组成。镀镍的最佳电流密度为2.0 m A/dm2,时间30 s。该纳米多孔Fe2O3–Fe3O4/Ni复合材料作为锂离子电池负极材料表现出更好的电化学性能──经过50次充放电循环后的放电比容量仍有438.3 m A·h/g,而Fe2O3–Fe3O4电极的放电比容量仅为110.6 m A·h/g。Fe2O3–Fe3O4/Ni电极的循环稳定性和倍率性能优异。

Iron oxides（Fe2O3–Fe3O4） with nanoporous structures was formed by anodization of iron foils in a NH4 F ＋ H2 O ethylene glycol solution, and then electrodeposited with nickel. After annealing at 400 ℃ for 0.5 h, a nanoporous iron oxides/nickel composite（Fe2O3–Fe3O4/Ni） was obtained. The effects of current density and time on the electrodeposition of nickel were discussed. The surface morphology, elemental composition, and phase of the composite were analyzed by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. The electrochemical performances were tested and compared with the nanoporous iron oxides without electrodeposited nickel（i.e. Fe2O3–Fe3O4）. The results indicated that the iron oxides are composed of Fe2O3 and Fe3O4. The optimal conditions for nickel electrodeposition are 2.0 m A/dm2 and 30 s. The nanoporous Fe2O3–Fe3O4/Ni composite as a negative electrode for lithium ion batteries exhibits improved electrochemical properties, as shown by the remaining specific discharge capacity of 438.3 m A·h/g after 50 charge/discharge cycles, while the specific discharge capacity of Fe2O3–Fe3O4 is only 110.6 m A·h/g. The Fe2O3–Fe3O4/Ni electrode has excellent cycling stability and rate performance.