Self-assembly synthesis of a unique stable cocoon-like hematite @C nanoparticle and its application in lithium ion batteries.

A novel cocoon-like FeO@C nanoparticle was fabricated via a facile hydrothermally molecular self-assembly procedure. Compared to bare FeO nanoparticles, the carbon coated FeO nanoparticles exhibit higher specific capacity, excellent rate capacity and cyclic stability as the anode in lithium ion batteries. These cocoon-like FeO@C nanoparticles carry enhanced lithium storage properties with a reversible capacity of 358mAhg after 150 cycles under the current density of 1000mAg, while the carbon-free bare FeO can only deliver a much lower capacity of 127.6mAhg with a continuously decreasing trend. The excellent performance of FeO@C is attributed to the coated carbon layers, which not only enhance the electronic conductivity but also reduce the stress upon the FeO nanoparticles caused by the volume change during the charge/discharge process.