Controllable synthesis of Fe3O4 polyhedron possessing excellent high-rate electrochemical performance for lithium-ion batteries

Fe 3 O 4 nanocrystals (NCs) composed of different proportion of {100} and {111} facets were prepared using oleic acid and decanoic acid as surfactant to mediate their growth process. It has been found that the morphology of Fe 3 O 4 NCs can be tuned by changing the ratio of oleic acid and decanoic acid. When tested as the anode materials in LIBs, the Fe 3 O 4 octahedrons obtained after annealing at 450   °C was found to exhibit superior electrochemical performances with a high reversible capacity of 882.6   mAh   g −1 at 1   A   g −1 over 200 cycles, whereas the Fe 3 O 4 cubooctahedron and cubes bearing poor electrochemical performances. The present results prove that the surface structure of Fe 3 O 4 polyhedrons significantly influence the utilization of Fe 3 O 4 active materials and hence their electrochemical performance although the morphology will be destroyed during cycling.