The lithium/sodium-ion storage properties of transition metal oxides often undergo startling volume variation and poor electrical conductivity. Herein, N, P and S doped dual carbon-confined Fe3O4 nanospheres (Fe3O4@C@G) are prepared by the multi-heteroatom-doped dual carbon-confined strategy. The first carbon layer results from multi-heteroatom-containing polymer derived N, P and S doped carbon to form Fe3O4@doped carbon core-shell nanostructure. And the second carbon layer results from the further encapsulated reduced graphene oxide (rGO) to form Fe3O4@doped carbon@graphene 3D architecture (Fe3O4@C@G). As expected, the resulting Fe3O4@C@G can be served as the universal anode materials towards lithium/sodium-ion batteries (LIBs/SIBs). Interestingly, Fe3O4@C@G delivers higher reversible capacity of 919 mAh g-1 at 0.1 A g-1 for LIBs. As for SIBs, Fe3O4@C@G also shows a high reversible capacity of 180 mAh g-1 after 600 cycles at 0.1 A g-1. Furthermore, the electrochemical reaction kinetics in LIBs/SIBs are investigated and Li+ full cells are also assembled to demonstrate its practical application.

中文翻译：

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掺杂多杂原子的双碳约束Fe3O4纳米球可作为锂/钠离子电池的高容量和长寿命阳极材料。

过渡金属氧化物的锂/钠离子存储特性经常会发生惊人的体积变化和不良的导电性。在此，通过多杂原子掺杂双碳受限策略制备了N，P和S掺杂的双碳受限Fe3O4纳米球（Fe3O4 @ C @ G）。第一碳层由含多杂原子的聚合物衍生的N，P和S掺杂的碳形成，形成Fe3O4掺杂的碳核-壳纳米结构。第二碳层来自进一步封装的还原氧化石墨烯（rGO），形成了Fe3O4 @掺杂的碳@石墨烯3D结构（Fe3O4 @ C @ G）。不出所料，生成的Fe3O4 @ C @ G可用作锂/钠离子电池（LIB / SIB）的通用阳极材料。有趣的是，Fe3O4 @ C @ G在0.1 A g-1下可为LIB提供919 mAh g-1的更高可逆容量。至于SIB Fe3O4 @ C @ G在0.1 A g-1下经过600次循环后还显示出180 mAh g-1的高可逆容量。此外，还对LIB / SIB中的电化学反应动力学进行了研究，并组装了Li +全电池以证明其实际应用。