A composite of Fe3O4@C and multilevel porous carbon as high-rate and long-life anode materials for lithium ion batteries.

The iron oxide-based anode materials are widely studied and reported due to their abundance, low cost, high energy density and environmental friendliness for lithium ion batteries (LIBs). However, the application of LIBs is always limited by the poor rate capability and stability. In order to tackle these issues, a novel material with carbon-encapsulated Fe3O4 nanorods stuck together by multilevel porous carbon (Fe3O4@C/PC) is prepared through directly carbonizing the Fe-based metal-organic framework under a nitrogen atmosphere. This novel material shows a high specific capacity and rate performance. The initial specific capacity can reach 1789 mAh g-1 at a current density of 0.1 A g-1, and the specific capacity still remains 1105.3 mAh g-1 and 783.5 mAh g-1 after 150 cycles at the current densities of 0.1 A g-1 and 1 A g-1, respectively. Even under a current density as high as 12 A g-1, the specific capacity can achieve 309 mAh g-1 after 2000 cycles with an average attenuation rate of 0.019% per cycle. Overall, the simple strategy, low cost and high capacity can make the practical application possible.