Fig. 1.

(a) Specific capacitance vursus scan rates for all prepared carbon. (b) Demonstration of supercapacitor devices prepared by hard carbons. (c) CV of KHC from scan rates 1 mV s⁻¹ to 100 mV s⁻¹. (d) GCD curves at different current density in 6 M KOH. (e) Nyquist plot in the frequency range from 0.1 GHz to 0.1 Hz at 5 mV amplitude voltage. (f) Plots of cycle stability over 6000 cycles for KHC. Reproduced with permission from Ref. [23]. Copyright 2019 Springer.