Conjugated cobalt‐based metal complex nanosheet for fabricating high‐performance supercapacitor electrode

Abstract In order to cope with the increasingly serious problem of energy shortage, supercapacitors have been developed as a clean and renewable energy source, and the supercapacitors with excellent energy density and long cycle life are imperative. Here, by employing a facile liquid–liquid (L‐L) interfacial method at room temperature (RT), a set of two‐dimensional (2D) metal complex nanosheets N1‐N3 have been synthesized by the facile coordination between Co 2+ ion and 2,3,6,7,10,11‐hexaiminotriphenylene (HITP). Given the layered superstructure with well‐ordered nanopores, the N1‐N3 electrodes displayed excellent capacities of 4751.9, 5770.9 and 6075.2 F g −1 at 1 A g −1 , and a good cyclic stability with 92.1% capacity retention after 1000 cycles for the N3 electrode. The asymmetric supercapacitor device with N3 as the positive electrode delivers a maximum energy density of 238.2 Wh kg −1 at a power density of 1610.1 W kg −1 and an excellent cycling stability with a capacitance retention of 109.1% after 5000 cycles. This is the best electroactive bottom‐up metal complex nanosheet reported so far for use in supercapacitor, which greatly expands the applicability of this 2D nanomaterial in energy device applications. image