Fig. 3: Electrochemical performance of the SnO2 nanocrystals with exposed {221} facets anchored on graphene (negative electrode) in half-cells.

a GCD curves. b The corresponding specific capacitances at various current densities. c CV curves and d the Lg (anodic currents) vs. Lg (sweep rates). e Separation of the capacitive (green) and diffusion currents in SnO2/graphene at a sweep rate of 10 mV s–1. f Normalized contribution ratios of the capacitive (green) and diffusion-controlled (gray) capacitances at different sweep rates