Fe3O4 nanoparticles encapsulated in graphitized and in-plane porous carbon nanocages derived from emulsified asphalt for a high-performance lithium-ion battery anode

In this work, C@Fe 3 O 4 composites were prepared through a typical template method with emulsified asphalt as carbon source, ammonium ferric citrate as transition metal oxide precursor, and NaCl as template. As an anode for lithium-ion batteries, the optimized C@Fe 3 O 4 -1:2 composite exhibits an excellent reversible capacity of 856.6 mA·h·g −1 after 100 cycles at 0.1 A·g −1 and a high capacity of 531.1 mA·h·g −1 after 300 cycles at 1 A·g −1 , much better than those of bulk carbon/Fe 3 O 4 prepared without NaCl. Such remarkable cycling performance mainly benefits from its well-designed structure: Fe 3 O 4 nanoparticles generated from ammonium ferric citrate during pyrolysis are homogenously encapsulated in graphitized and in-plane porous carbon nanocages derived from petroleum asphalt. The carbon nanocages not only improve the conductivity of Fe 3 O 4 , but also suppress the volume expansion of Fe 3 O 4 effectively during the charge–discharge cycle, thus delivering a robust electrochemical stability. This work realizes the high value-added utilization of low-cost petroleum asphalt, and can be extended to application of other transition-metal oxides-based anodes.