Fig 1

Schematic for design principles for enhancing the electrochemical performance of iron-based heterostructure anode materials."

Fig 2

The diagram of bond alignment and energy storage mechanisms of heterostructures 38."

Fig 3

(a) Schematic illustration of the formation mechanism and direction of internal E-field for Fe9S10@MoS2@C during discharge and charge processes 36; (b) built-in electric field diffusion enhancement model at heterostructures interface 39."

Fig 4

Schematic illustration of construction methods for heterogeneous anode materials 45, 46, 49, 50."

Fig 5

The main characterization methods for heterojunction structures 52, 54, 55, 57."

Fig 6

(a) Schematics of synthesis of Fe2O3/NG and Fe2O3/Fe3O4/NG composites; (b) SEM, (c) HRTEM images and (d) O 1s spectra of Fe2O3/Fe3O4/NG composites; (e) Cycling performance at 0.1 A∙g−1 of the Fe2O3/NG and Fe2O3/Fe3O4/NG 62; (f) the schematic fabrication process and (g) SEM images of CoSe2@Fe3O4@Fe2O3 64."

Fig 7

(a) Schematic illustration of the synthesis process and (b) TEM images of the Fe2O3@MoS2/C composite 65;(c) schematic illustration of synthesis process of the SnS/Fe2O3-G heterostructure; (d) cycling performance at 0.2 A∙g−1 of the SnS/Fe2O3; (e) energy barriers for Na+ migration of the SnS and SnS/Fe2O3 heterostructure 66; (f) SEM images of Co3O4-Fe2O3; (g) Cycling stability at a current rate of 50 mA∙g−1 69."

Fig 8

(a) Schematic illustration of the synthesis process, (b) SEM image and (c) long-term cyclic performance at 1.0 A∙g−1 for Fe1−xS/MoS2 nanocomposite 73; (d) TEM image and (e) cyclic performance of CuS/FeS2@NC; (f) schematic illustration of the synergistic effects of the heterostructured CuS/FeS2@NC 75."

Fig 9

(a) Preparation procedure of FeS2/TiO2@CNFs heterostructure materials; (b–e) SEM, TEM and cyclic performance of FeS2/TiO2@CNFs 76; (f) schematic illustration of MnS/FeS2@CNFs heterogeneous interface; (g) rate capacities of MnS@CNFs, FeS2@CNFs and MnS/FeS2@CNFs 78."

Fig 10

(a) Schematic of the synthesis and (b) SEM images of Fe1−xS@SC HSs; (c) contour plots of in situ XRD results of Fe1−xS@SC HSs electrode against the voltage profile during the initial cycle at cutoff voltage of 0.1–2.5 V 79; (d) schematic illustration of the fabrication process and (e) cycle performance at 1 A∙g−1 of the SFS/C composite; (f) in situ XRD contour plots of the SFS/C electrode against the charge/discharge profile during the initial sodiation/desodiation cycle 80."

Table 1

Sodium storage properties of typical heterogeneous Fe-based sulfide anode materials."

Fig 11

(a, b) SEM images, (c) selected area electron diffraction image, (d) TEM image and (e) cyclic performance of CoP/FeP@RGO 91; (f) Schematic illustration of the synthesis of CoP/FeP@PCNFs and the Na+ storage enhancement mechanism; (g) Electrostatic potential drop diagram of CoP/FeP 92; (h) Schematic illustration of the preparation and (i) rate capacities of FeP/CoP-NA; (j) Charge density difference at the interface before Na insertion 93."

Fig 12

(a) Schematic illustration of the synthesis process and (b) cycling performance of Fe-Ni-P arrays 94; (c) schematic illustration of the synthesis processes of Cu-Fe-P/TiN; (d, e) SEM images, (f) HR-TEM image and (g) SAED pattern of Cu-Fe-P/TiN 95."

Fig 13

(a) SEM image, (b) cyclic performance at 5 A∙g−1 and (c) DFT calculation results of Fe3Se4/FeSe@NCNF 102; (d) schematic diagram of the synthesis and (e) cyclic performances of Fe/FeSe2/Fe3Se4 103."

Fig 14

(a) Schematic diagram of the synthesis of Fe3Se4/ZnSe@C 104; (b) schematic of the fabrication and (c) ex situ XRD and contour plots of FCSe@C@void@C; (d) ex situ HRTEM and SAED images at fully discharged state and fully charged state of FCSe@C@void@C 105; (e) schematic illustration of the preparation process of FeSe2/MoSe2; (f) ex situ XRD of FeSe2/MoSe2 electrode 106."

Fig 15

(a) Schematic of the synthesis process and (b) SEM image of FePS3@MXene 114; (c) rate performance and (d) cyclic performance of the NVP/C//FePS3@NC (3 : 1) full-cell at 0.1 A∙g−1; (e) charge density differences of Na+ adsorbed on FePS3 and FePS3@NC for top view and side view 115."

Fig 16

Advantages and challenges of Fe-based heterostructured anode materials in SIBs."