fig7

Figure 7. (A) CV curve with a scanning rate of 0.1 mV·s^-1; (B) charge/discharge curve with a current density of 0.1 A·g^-1; (C) capacity test diagram at a current density of 0.1 A·g^-1; (D and E) rate performance test diagram a current density from 0.2 to 5.0 A·g^-1; and (F) stability test diagram with 500 cycles a current density of 2.0 A·g^-1 for helical multi-shelled carbon nanospheres-based KIBs anode. This figure is quoted with permission from Peng et al.^[51]. CV: Cyclic voltammetry; KIBs: potassium-ion batteries.