Fabrication of Fe3 O4 Dots Embedded in 3D Honeycomb-Like Carbon Based on Metallo-Organic Molecule with Superior Lithium Storage Performance.

A novel metallo-organic molecule, ferrocene, is selected as building block to construct Fe3 O4 dots embedded in 3D honeycomb-like carbon (Fe3 O4 dots/3DHC) by using SiO2 nanospheres as template. Unlike previously used inorganic Fe3 O4 sources, ferrocene simultaneously contains organic cyclopentadienyl groups and inorganic Fe atoms, which can be converted to carbon and Fe3 O4 , respectively. Atomic-scale Fe distribution in started building block leads to the formation of ultrasmall Fe3 O4 dots (≈3 nm). In addition, by well controlling the feed amount of ferrocene, Fe3 O4 dots/3DHC with well-defined honeycomb-like meso/macropore structure and ultrathin carbon wall can be obtained. Owing to unique structural features, Fe3 O4 dots/3DHC presents impressive lithium storage performance. The initial discharge and reversible capacities can reach 2047 and 1280 mAh g(-1) at 0.05 A g(-1) . With increasing the current density to 1 and 3 A g(-1) , remarkable capacities of 963 and 731 mAh g(-1) remain. Moreover, Fe3 O4 dots/3DHC also has superior cycling stability, after a long-term charge/discharge for 200 times, a high capacity of 1082 mAh g(-1) can be maintained (80% against the capacity of the 2nd cycle).