An ultralight and highly compressible anode for Li-ion batteries constructed from nitrogen-doped carbon enwrapped Fe3O4 nanoparticles confined in a porous 3D nitrogen-doped graphene network

•An ultralight and highly compressive nanohybrid was made by hydrothermal reaction.•The nanohybrid integrates N-doped graphene, Fe3O4 nanoparticles, and N-doped carbon.•The nanohybrid with highly porous structure exhibits ultralow density (8.47 mg cm−3).•The nanohybrid is among the most efficient Fe3O4-based anode materials ever reported.

Anode materials made of nanohybrids of graphene and transition metal oxides have been widely investigated. However, less attention has been paid to their density and compressibility. In this study, we synthesized an ultralight, highly compressive, and porous nanohybrid. This nanohybrid integrates nitrogen-doped graphene (NG), Fe3O4 nanoparticles, and N-doped carbon (NC) shell on each Fe3O4 nanoparticle. The Fe3O4 nanoparticles with NC shell are connected to and confined by 3D NG which forms a three-dimensional (3D) interconnected conductive scaffold. This sophisticated nanostructure was synthesized by a facile and scalable one-step hydrothermal reaction followed by calcination. The resultant Fe3O4/NC/NG nanohybrid with highly porous structure exhibits ultralow density (8.47 mg cm−3) and supercompressibility. In addition, the Fe3O4/NC/NG nanohybrid delivers high reversible capacity of 952 mAh g−1 at 200 mA g-1, excellent high rate capacity (427 mAh g−1 at 4000 mA g-1), and prolonged cycling life (905 mAh g−1 at 200 mA g-1 after 100 cycles). The Fe3O4/NC/NG nanohybrid is a very efficient Fe3O4-based anode material for Li-ion batteries. These promising results demonstrate that this facile and scalable strategy holds great potential in the fabrication of high-performance compressive and ultralight metal oxide-graphene electrochemical devices.

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