Figure 6.

(A) Schematic illustration of an ultraflexible planar supercapacitor constructed with a hybrid film as the working electrode, a current collector, and a gel electrolyte on a plastic polyethylene terephthalate (PET) substrate. (B) The planar supercapacitor unit, showing that the 2D hybrid thin film functions as two symmetric working electrodes. (C) The hybrid thin film was formed by stacking layers of chemically integrated quasi-2D δ-MnO₂ nanosheets and graphene sheets. (D) TEM image of the 2D hybrid structure with δ-MnO₂ nanosheets integrated on graphene surfaces. (E) Schematic description of the 2D planar ion transport favored within the 2D δ-MnO₂/graphene hybrid structures. (F) Comparison of specific capacitance values for the supercapacitors based on hybrids and based on graphene. (G) Capacitance retention (blue) and Coulombic efficiency (red) of the planar supercapacitor device based on hybrids over 7,000 charge/discharge cycles (Peng et al., 2013).