Figure 3. Supercapacitor charge-discharge characteristics of coated and uncoated porous silicon.

(a–b) Galvanostatic discharge curves for (a). graphene-coated P-Si and (b). uncoated, pristine P-Si at different, consistent charging currents after charging to 2.3 V in EMIBF₄ electrolyte. (c). three consecutive charge-discharge curves taken at 0.65 A/g for graphene-coated P-Si, showing the triangular charge-discharge curve. (d). Capacitance retention over 5000 cycles measured for graphene-coated P-Si, with retention % labeled at ~1500 and 5000 cycles. Inset in this is capacitance retention for pristine P-Si cycled both at 2.3 V (same as graphene-coated P-Si) and at 1 V inside the electrochemical window.