Aqueous high-voltage all 3D-printed micro-supercapacitors with ultrahigh areal capacitance and energy density

Abstract With the rapid development of integrated and miniaturized electronics, the planar energy storage devices with high capacitance and energy density are in enormous demand. Hence, the advanced manufacture and fast fabrication of microscale planar energy units are of great significance. Herein, we develop the aqueous planar micro-supercapacitors with ultrahigh areal capacitance and energy density via an efficient all-3D-printing strategy, which can directly extrude the inks containing the active material and gel electrolyte onto the substrate to prepare electrochemical energy storage devices. Both the printed active carbona/exfoliated graphene (AC/EG) electrode ink and electrolyte gels are highly processable with outstanding conductance (∼97 S cm-1 of electrode; ∼34.8 mS cm-1 of electrolyte), thus benefiting the corresponding shaping and electrochemical performances. Furthermore, the as-3D-printed symmetric MSCs can be operated stably at a high voltage up to 2.0 V in water-in-salt electrolyte, displaying ultrahigh areal capacitance of 2381 mF cm-2 and exceptional energy density of 331 μWh cm-2, superior to previous printed micro energy units. In addition, we can further tailor the integrated 3D-printed MSCs in parallel and series with various voltages and current outputs, enabling metal-free interconnection. Therefore, our all-3D-printed MSCs place a great potential in developing high-power micro-electronics fabrication and integration.