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

Abstract

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.