Abstract Fe3O4 shows great potential in the energy storage field; however, the low conductivity, particles aggregation and large volume change during the electrochemical process seriously limit its practical application. Here, spindle-shaped core-shell Fe3O4@N-doped carbon scattered in graphene (Fe3O4@NCm/rGO) has been successfully fabricated. SEM and TEM results indicate that the N-doped carbon shell with a thickness of 10 nm was homogenously coating on the spindle-shaped Fe3O4 surface, and at the same time the Fe3O4@NCm particles evenly dispersed on the graphene sheets. Profiting from the N-doped carbon shell and graphene, the Fe3O4@NCm/rGO electrode delivers excellent electrochemical performances both in Li and Na ion half-cells (720 mAh g−1 at 1000 mA g−1 after 500 cycles and 237 mAh g−1 at 1000 mA g−1 after 2500 cycles for Li and Na ion half-cells, respectively). And most importantly, the Fe3O4@NCm/rGO electrode also presents superior lithium and sodium storage performances in Li and Na ion full-cells with 526 mAh g−1 for Li-ion full cell and 192 mAh g−1 for Na-ion full cell. These results demonstrate that the Fe3O4@NCm/rGO composites have great promising applications as anodes in both commercial Li/Na-ion batteries.

中文翻译：

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分散在石墨烯中的纺锤形核壳Fe3O4@N掺杂碳复合材料作为锂/钠离子电池的优异负极材料

摘要 Fe3O4在储能领域显示出巨大的潜力；然而，电化学过程中电导率低、颗粒聚集和体积变化大，严重限制了其实际应用。在这里，已经成功地制造了分散在石墨烯中的纺锤形核壳 Fe3O4@N 掺杂碳（Fe3O4@NCm/rGO）。SEM和TEM结果表明，10 nm厚的N掺杂碳壳均匀地包覆在纺锤形Fe3O4表面，同时Fe3O4@NCm颗粒均匀分散在石墨烯片上。受益于 N 掺杂的碳壳和石墨烯，Fe3O4@NCm/rGO 电极在 Li 和 Na 离子半电池中均具有出色的电化学性能（500 次循环后在 1000 mA g-1 下为 720 mAh g-1，2500 次循环后在 1000 mA g-1 下为 237 mAh g-1分别为 Li 和 Na 离子半电池）。最重要的是，Fe3O4@NCm/rGO 电极在锂离子和钠离子全电池中也表现出优异的锂和钠存储性能，锂离子全电池为 526 mAh g-1，钠离子全电池为 192 mAh g-1细胞。这些结果表明，Fe3O4@NCm/rGO 复合材料在商业锂/钠离子电池中作为负极都有很大的应用前景。