Mn-doped Ni-coordination supramolecular networks for binder-free high-performance supercapacitor electrode material

A new Mn-doped coordination supramolecular network (CSN) was synthesized on nickel foam directly by a simple one-step hydrothermal method. Compared with the pure CSN electrode (∼2.46 C cm⁻² at 10 mA cm⁻²), this Mn-doped binder-free electrode showed an ultrahigh areal capacity (∼8.12 C cm⁻² at 10 mA cm⁻²). In addition, when the current density increased from 10 mA cm⁻² to 50 mA cm⁻², it had a good rate capability with 73.33% capacitance retention. For practicality, an asymmetrical supercapacitor (ASC) was assembled by Activated Carbon (AC) electrode and the Mn-doped CSN electrode. The device not only could achieve a maximum energy density of 3.41 mW h cm⁻³ at the power density of 44.98 mW cm⁻³, but also could exhibit excellent stability after 4000 cycles, with the capacitance retention of 90.14%. The above results indicate that the Mn-doped CSNs are promising electrode materials for supercapacitors in energy storage.