Layered conducting polymers have drawn widespread interest in electrochemical energy systems with capacitive ion storage. However, the semi-infinite ion diffusion through the lengthy path within their lamellar structures restricts the power performance, especially in high mass loading electrodes (>10 mg cm^–2). Herein, we improve the ion diffusion in layered conducting polymers by constructing ion-penetrable defects through mechanical modulation of hydrogen bonding, i.e., ball milling. The ball-milled layered conducting polymers endow the fabrication of high mass loading (up to 30 mg cm^–2) electrodes for electrochemical capacitors (ECs) with a remarkable areal capacitance of 1.71 F cm^–2 and volumetric capacitance of 148.2 F cm^–3 at 150 mA cm^–2. Asymmetric ECs are further prototyped, delivering a high areal energy of 0.916 mWh cm^–2 and a volumetric energy of 28.68 Wh L^–1 at 12.5 mW cm^–2. These findings represent a critical step forward to the practical application of layered conducting polymers for high-power devices with miniaturized configuration.