Mechanically Improving Ion Diffusion in Layered Conducting Polymers for Compact Energy Storage

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.