Boosting Zinc‐Ion Hybrid Capacitors with Mesoporous Carbon Derived from Highly Graphitized Carbon Quantum Dots

Zinc‐ion hybrid capacitor (ZIHC) with high‐energy density and inherent safety is considered an emerging energy storage technology. However, its rate performance and cycling stability under high‐current density conditions are limited by the electrical conductivity and mesoporosity of electrode materials, failing to meet the demand for fast charging. Herein, a novel strategy is proposed to prepare highly mesoporous carbons (MCs) by using high‐graphitized carbon quantum dots (CQDs) as precursors. The enhanced dispersion of CQDs in molten KOH during activation occurs, thereby enabling more intimate contact and effective activation. MCs are endowed with ultrahigh mesopore ratio (83.3%), high‐specific surface area (3328 m 2 g −1 ), and sound electrical conductivity (11.39 S cm −1 ). The ZIHCs assembled with MCs deliver superior energy density (218.24 Wh k g −1 ). Even at a high‐current density of 20 A g −1 , the electrode maintains a specific capacity of 116.4 mAh·g −1 . The excellent rate capability stems from the efficient synergistic effect formed by the conjugated π‐electron system of graphitic microdomains in the carbon skeleton and the ion transport channels of mesoporous structures. The work highlights CQDs as an innovative precursor for constructing mesoporous carbons and enables high‐rate energy storage devices.