Scalable Synthesis of an Artificial Polydopamine Solid‐Electrolyte‐Interface‐Assisted 3D rGO/Fe3O4@PDA Hydrogel for a Highly Stable Anode with Enhanced Lithium‐Ion‐Storage Properties

Abstract 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.