Self-assembly of pyramid-like magnetites with hierarchical structures as lithium battery anode materials

Pyramid-like magnetite crystals are assembled via a simple one-pot hydrothermal process with industrialized environmental free raw materials. It is revealed that these crystals have hierarchical structures which are self-assembled of nano-sized ultrafine magnetite spheres. The electrochemical properties of the as-prepared magnetite are studied by galvanostatic cell cycling at different current rates. The electrodes exhibit high reversible specific capacity (about 1600 mA h g−1 at 40 mA g−1 ) at low rate and good cycle property at 1 C. The specific capacity increases after it reaches a minimum, which is believed to be related to the formation of SEI film. After cycled 500 times at 1 C, the reversible capacity is still higher than 340 mA h g−1.

► Novel pyramid-like micron magnetite crystals with simple one-pot hydrothermal process at low temperature.
► Commercialized steel flakes often used as back-up plates in Li-ion test cells are used as raw materials.
► Magnetite crystals are self-assembled of ultrafine nano-spheres.
► The material exhibits high reversible specific capacity and excellent cycle property.