Abstract:
In this work, a birnessite-type MnO2/carbon composite with hierarchical nanostructures was synthesized using KMnO4 solution and spent
printing carbon grains. A hybrid electrochemical supercapacitor device was fabricated based on the birnessite-type MnO2–carbon composite
electrode and carbonized iron-polyaniline/nickel graphene foam as positive and negative electrodes, respectively. At the lowest specific current
of 1.0 A g−1
and cell potential of 2.2 V in 2.5M KNO3 electrolyte, the device displayed a high energy and power density of 34.6 W h kg−1
and 1100.0 W kg−1
, respectively. The device further displayed long-term cycling stability with a capacitance retention of 98% over 10 000
galvanostatic charge–discharge cycles at 10 A g−1
. This device displays the overall excellent electrochemical performance.
