Fe₃O₄-Embedded and N-Doped Hierarchically Porous Carbon Nanospheres as High-Performance Lithium Ion Battery Anodes

Recently, Fe₃O₄-based materials have been widely studied as anodes in lithium-ion batteries (LIBs) because of the large theoretical capacity (924 mAh g^-1) and environmental benignity. Unfortunately, these materials suffer from the low practical capacity and poor cycling stability. Herein, we developed a simple "softlating" approach to fabricate multiple Fe₃O₄ nanoparticles-embedded and N-doped hierarchically porous carbon nanospheres (Fe₃O₄@N-HPCNs) as anodes for LIBs by utilizing the self-assembly among polystyrene-b-poly(acrylic acid), cetyltrimethylammonium bromide, and hydrophobic Fe₃O₄ nanoparticles in oil/water system. The resultant Fe₃O₄@N-HPCNs present a well-defined spherical morphology, high specific surface area, and unique dual-mesoporous core structures with multiple Fe₃O₄ nanoparticles in the large-mesopore channels. More importantly, the Fe₃O₄@N-HPCNs anode exhibits high reversible specific capacities of 1240 mAh g^-1 (after 100 cycles at 0.1 A g^-1) and 581 mAh g^-1 (after 400 cycles at 1 A g^-1). Even at 10 A g^-1, a specific capacity of ca. 290 mAh g^-1 is still retained, indicating its excellent rate capability. Therefore, such a "softlating" approach is expected to provide us a new pathway to design and prepare other nanoparticles@porous carbon anodes for LIBs.