Post-lithium ion hybrid capacitors have great potential to serve as mid-to large-scale energy storage applications
because of their high energy/power densities, abundant resources and low cost. Here we report a highperformance
dual-carbon potassium ion hybrid capacitor (PIHC) based on two carbon electrode materials
derived from a single precursor–ethylene diamine tetraacetic acid tetrasodium (EDTA-4Na). By means of a simple
calcination, the EDTA-4Na can be directly converted to a three-dimensional (3D) nitrogen-doped framework
carbon (3DNFC) that exhibits high reversible capacity and good electrochemical kinetic property for potassium
ion storage. Such 3DNFC can be further converted to a 3D nitrogen-doped framework activated carbon (3DNFAC)
that shows ultrahigh specific surface area (3839m2 g 1) and excellent capacitance performance. Using the 3DNFC
as battery-type anode and the 3DNFAC as capacitor-type cathode, a dual-carbon PIHC is fabricated, and it is able
to normally work at 0–4.2 V, delivers high energy and power densities (163.5 Wh kg 1 at 210Wkg 1, and
76.4 Wh kg 1 at 21 000Wkg 1), and exhibits outstanding cycling stability (91.7% capacity retention after 10 000
cycles at 2.0 A g 1), which are all the best values for the state-of-the-art PIHCs.