fig5

Figure 5. (A) CV curves of N/S-CNF-700, aPCNF, and N/S-CNF-700//aPCNF at 2 mV s^-1; Electrochemical properties of N/S-CNF-700//aPCNF device: (B) CV curves; (C) GCD profiles from 0.1 to 5.0 A g^-1; (D) Ragone plots compared with reported PIHCs^[6,64-68]; (E) self-discharge; (F) leakage current; and (G) cycling stability at 1.0 A g^-1. CV: Cyclic voltammetry; N/S-CNFs: N/S co-doped carbon nanofibers; aPCNF: synthesize activated porous carbon nanofibers; GCD: galvanostatic charge-discharge tests; PIHCs: potassium ion hybrid capacitors.