fig4

Figure 4. (A) Schematic illustration of 2D materials-based 3D-printed hierarchical structures; (B-i) FE-SEM images of (2D + 1D) graphene-CNTs mixed hybrid material at various magnifications (scale bar: 50 μm and 200 nm, respectively); (B-ii) TEM microstructure of graphene-CNTs mixed hybrid material with inset of schematic illustration of 2D + 1D hybrid material (scale bar: 40 nm); (C) Schematic demonstration of insufficient and sufficient ion migrations for conventional thick-film and DIW advanced graphene-MWCNTs hybrid electrode materials, respectively^[85]; (D and E) TEM microstructures of the 3D GA and SF-3D GA samples, respectively; (F) Nitrogen adsorption-desorption isotherms of the 3D GA and SF-3D GA samples, while inset displays pore-size distribution plots of the respective samples; (G) Areal capacitance contributions of 3D GA, SF-GA, and SF-3D GA reported at various current densities; (H) Areal capacitance of SF-3D GA electrode materials as a consequence of electrode varied thickness reported at 5 mA cm^-2; and (I) a radar chart illustrates the five points of performance comparison including mass loadings of the electrode materials, BET surface area, specific capacitance (F g^-1), areal capacitance (mF cm^-2), and rate-capability (~5 to 100 mA cm^-2) of 3D GA, SF-GA, and SF-3D GA^[86].