Electrostatic self-assembled MXene–graphene oxide composite electrodes for planar supercapacitors

MXene based layered materials have exhibited excellent performance in supercapacitor applications owing to their high conductivity. However, device planarization hinders their broader ability in a film-based energy storage device. Here, we have demonstrated the fabrication of self-assembled MXene–graphene oxide (M-GO) composites based on the electrostatic interaction between MXene and GO solutions. The as-prepared M-GO composite possessed homogeneous structures and tunable conductivities according to different GO contents, which benefit both charge storage and ions transmission. The first-assembly sandwiched supercapacitors based on these M-GO composites showed a maximum specific capacitance value of 39.0 mF/cm2 (10.9 mF/cm2 for MXene based devices). The enhanced electrochemical performance after self-assembly was due to the improved interface effect between electrodes and electrolytes. Additionally, the introduction of GO guarantees the completeness of designed M-GO patterns without the need for additives, and it is worth noting that with the assistance of a laser fabrication technique, planar supercapacitors based on the most suitable M-GO (with mass ratio of M:GO = 1:1) composite could be obtained by ablating the unwanted areas. Additionally, planar M-GO based supercapacitors also exhibited excellent electrochemical performance, which demonstrated the great potential of M-GO composite supercapacitors in wearable electronic applications.