Magnetite (Fe₃O₄) has drawn great attention in the field of lithium‐ion batteries (LIBs) due to its promising high theoretical capacity and abundance in nature. However, rapid capacity fading, low charge/discharge rate and low capacity exceedingly limit the application of bare Fe₃O₄ anode. Here, we report a facile and scalable method to construct multilayered reduced graphene oxide (rGO)/Fe₃O₄@polydopamine (PDA) hydrogel (rGO/Fe₃O₄@PDA hydrogel) for the anodes of LIBs. During the lithiation/delithiation processes, PDA and rGO can effectively inhibit the volume change and avoid structural pulverization. rGO backbone also provides sufficient electrical conductivity and a high specific surface area. The PDA layer suppresses the repetitive growth and thickening of solid‐electrolyte interphase (SEI), playing a role of artificial SEI. As a result, high capacity and superior cycle stability (1358 mAh g⁻¹ after 300 cycle at 1 A g⁻¹) as well as satisfying rate performance (around 600 mAh g⁻¹ at 3 C), fast charge/discharge rate (712 mAh g⁻¹ after 2000 cycles at 3 A g⁻¹), high columbic efficiency and stable reverse reaction are achieved. Interestingly, capacity growth can be observed in the multilayered rGO/Fe₃O₄@PDA anode owing to the gradual activation of tight encapsulation by rGO sheets. This design concept and structural construction strategy are hopeful be extended to other systems for the next‐generation advanced LIBs.

中文翻译：

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人工聚多巴胺固体电解质界面辅助3D rGO / Fe3O4 @ PDA水凝胶的可扩展合成，具有增强的锂离子存储性能，可用于高度稳定的阳极

磁铁矿（Fe ₃ O ₄）由于其有希望的高理论容量和自然界中的丰度而备受锂离子电池（LIBs）领域的关注。然而，快速的容量衰减，低的充电/放电速率和低的容量极大地限制了裸Fe ₃ O ₄阳极的应用。在这里，我们报告了一种简便且可扩展的方法来构造多层还原氧化石墨烯（rGO）/ Fe ₃ O ₄ @聚多巴胺（PDA）水凝胶（rGO / Fe ₃ O ₄@PDA水凝胶）用于LIB的阳极。在锂化/脱锂过程中，PDA和rGO可以有效抑制体积变化并避免结构粉化。rGO主链还提供了足够的电导率和高比表面积。PDA层抑制了固体电解质中间相（SEI）的重复生长和增稠，起到了人工SEI的作用。结果，高容量和优异的循环稳定性（在1 A g ^-1下300次循环后为1358 mAh g ^-1）以及令人满意的速率性能（在3 C下约为600 mAh g ^-1），快速充电/放电速率（ 712毫安克^-1后3 A G 2000次循环^-1），可实现高的柱效和稳定的逆反应。有趣的是，由于rGO片材逐渐激活紧密封装，在多层rGO / Fe ₃ O ₄ @PDA阳极中可以观察到容量的增长。希望将此设计概念和结构构造策略扩展到下一代高级LIB的其他系统。