Figure 5: Comparison of the energy and power densities of HGF-ECs with other state-of-art energy storage technologies.

(a) Photographs of one HGF film electrode and one assembled symmetric HGF-EC. (b) Gravimetric and volumetric energy densities (normalized by the total weight or volume of both electrodes in each EC) and volumetric stack energy densities (normalized by the volume of the whole EC including two electrodes, two current collectors, electrolyte and one separator without packaging) for ECs made from various carbon materials. Areal mass loading of electrode materials: activated carbon (AC: 5 to 10 mg cm⁻²) (ref. 4), single-walled carbon nanotube (5 mg cm⁻²) (ref. 31), activated microwave exfoliated GO (2.5 mg cm⁻²) (ref. 12), electrolyte-mediated graphene (10 mg cm⁻²) (ref. 16), HGF (10 mg cm⁻²). (c) Ragone plots of gravimetric energy density versus gravimetric power density for HGF-EC in comparison with lead-acid batteries³, lithium-ion battery³, commercial ECs³. (d) Ragone plots of volumetric energy density versus volumetric power density for HGF-EC in comparison with lead-acid batteries^1,3, lithium thin-film battery³², commercial activated carbon-ECs^4,15. The energy and power densities are normalized by the actual weight or volume of the entire device stack including two electrodes, two current collectors, electrolyte, one separator and packaging.