A 2D Conductive Organic–Inorganic Hybrid with Extraordinary Volumetric Capacitance at Minimal Swelling

Rational design and synthesis of 2D organic-inorganic hybrid materials is important for transformative technological advances for energy storage. Here, a 2D conductive hybrid lamella and its intercalation properties for thin-film supercapacitors are reported. The 2D organic-inorganic hybrid lamella comprises periodically stacked 2D nanosheets with 11.81 Å basal spacing, and is electronically conductive (605 S m^-1 ). In contrast to the pre-existing organic-based 2D materials, this material has extremely low gas-permeable porosity (16.5 m² g^-1 ) in contrast to the high ionic accessibility. All these structural features collectively contribute to the high capacitances up to 732 F cm^-3 , combined with small structural swelling at as low as 4.8% and good stability. At a discharge time of 6 s, the thin-film intercalation electrode delivers an energy density of 24 mWh cm^-3 , which universally outperforms the surface-dominant capacitive processes in porous carbons.