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 "soft-templating" 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 "soft-templating" approach is expected to provide us a new pathway to design and prepare other nanoparticles@porous carbon anodes for LIBs.