ABSTRACT Supercapacitors based on reduced graphene oxide (rGO) are promising next‐generation energy storage devices, yet their performance remains limited by suboptimal energy storage density. Here, we report an innovative post‐treatment strategy in which residual electrolyte acid passively activates rGO electrodes simply by storage in ambient air after initial electrochemical measurements. This facile process increased the specific capacitance by 16%–39% (up to 107 F/g) without the need for additional chemical or thermal treatments. Systematic analysis revealed that the activation effect was strongly dependent on the initial oxidation level of rGO: high‐oxidation electrodes experienced pore narrowing and reduced rate capability, whereas low‐oxidation electrodes exhibited pore widening and enhanced high‐rate performance. These findings demonstrate a simple, low‐cost, and scalable approach to post‐fabrication activation of carbon‐based supercapacitors, offering a new pathway to enhance next‐generation energy storage devices.
Lee et al. (Sun,) studied this question.