A hierarchical FeS/RGO/FeS composite in situ grown on Fe foil was designed and prepared via an Fe foil-involved one-step hydrothermal route, in which Fe foil acted as the Fe source for the lower FeS layer, reductant of GO and subsequent current collector. The as-prepared FeS/RGO/FeS@Fe showed a high specific capacity of 247.5 C g⁻¹ (206.25 F g⁻¹) and good cyclability with 118% capacity retention after 5000 cycles when directly used as an electrode. Additionally, an asymmetric supercapacitor (ASC) was assembled using Ni(OH)₂ and FeS/RGO/FeS@Fe as the positive electrode and negative electrode, respectively. This ASC exhibited maximum power density and energy density of 20 000 W kg⁻¹ and 34.07 W h kg⁻¹, respectively, suggesting that FeS/RGO/FeS is a promising negative electrode material.

中文翻译：

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分层FeS / RGO / FeS @ Fe箔作为不对称超级电容器的高性能负极†

通过涉及Fe箔的一步式水热法设计和制备了在Fe箔上原位生长的分层FeS / RGO / FeS复合材料，其中Fe箔充当下部FeS层的Fe源，GO的还原剂和随后的Fe集电器。当直接用作电极时，所制备的FeS / RGO / FeS @ Fe具有247.5 C g ^-1（206.25 F g ^-1）的高比容量和良好的可循环性，在5000次循环后具有118％的容量保持率。另外，使用Ni（OH）₂和FeS / RGO / FeS @ Fe分别作为正极和负极组装不对称超级电容器（ASC）。该ASC的最大功率密度和能量密度为20000 W kg ^-1和34.07 W h kg ^-1，表明FeS / RGO / FeS是一种很有前途的负极材料。