Supercritical Carbon Dioxide Assisted Deposition of Fe3O4 Nanoparticles on Hierarchical Porous Carbon and Their LithiumStorage Performance

A composite of highly dispersed Fe3O4 nanoparticles (NPs) anchored in three-dimensional hierarchical porous carbon networks (Fe3O4/3DHPC) as an anode material for lithium-ion batteries (LIBs) was prepared by means of a deposition technique assisted by a supercritical carbon dioxide (scCO(2))-expanded ethanol solution. The as-synthesized Fe3O4/3DHPC composite exhibits a bimodal porous 3D architecture with mutually connected 3.7nm mesopores defined in the macroporous wall on which a layer of small and uniform Fe3O4 NPs was closely coated. As an anode material for LIBs, the Fe3O4/3DHPC composite with 79wt% Fe3O4 (Fe3O4/3DHPC-79) delivered a high reversible capacity of 1462mAhg(-1) after 100 cycles at a current density of 100mAg(-1), and maintained good high-rate performance (728, 507, and 239mAhg(-1) at 1, 2, and 5C, respectively). Moreover, it showed excellent long-term cycling performance at high current densities, 1 and 2Ag(-1). The enhanced lithium-storage behavior can be attributed to the synergistic effect of the porous support and the homogeneous Fe3O4 NPs. More importantly, this straightforward, highly efficient, and green synthetic route will definitely enrich the methodologies for the fabrication of carbon-based transition-metal oxide composites, and provide great potential materials for additional applications in supercapacitors, sensors, and catalyses.