Understanding the Degradation Mechanisms of Conducting Polymer Supercapacitors

• Published in: Macromolecular rapid communications. 2024-01, Vol.45 (1), p.e2300237-n/a
• Main Authors: Chang, Xueying, Yang, Zhiyin, Huang, Ailun, Katsuyama, Yuto, Lin, Cheng‐Wei, El‐Kady, Maher F., Wang, Chenxiang, Kaner, Richard B.
• Format: Article
• Language: English
• Subjects: Aniline; aniline trimer; Capacitance; Carbon nanotubes; Conducting polymers; Cycles; cycling stability; Degradation; Electrochemical analysis; Electrochemistry; Electrode materials; Electrodes; Nanotechnology; Nanotubes; Oligomers; Polyanilines; Polymers; Porosity; Stability; Supercapacitors; Trimers
• ISSN: 1022-1336; 1521-3927
• DOI: 10.1002/marc.202300237

Conducting polymers like polyaniline (PANI) are promising pseudocapacitive electrode materials, yet experience instability in cycling performance. Since polymers often degrade into oligomers, short chain length anilines have been developed to improve the cycling stability of PANI‐based supercapacitors. However, the capacitance degradation mechanisms of aniline oligomer‐based materials have not been systematically investigated and are little understood. Herein, two composite electrodes based on aniline trimers (AT) and carbon nanotubes (CNTs) are studied as model systems and evaluated at both pre‐cycling and post‐cycling states through physicochemical and electrochemical characterizations. The favorable effect of covalent bonding between AT and CNTs is confirmed to enhance cycling stability by preventing the detachment of aniline trimer and preserving the electrode microstructure throughout the charge/discharge cycling process. In addition, higher porosity has a positive effect on electron/ion transfer and the adaptation to volumetric changes, resulting in higher conductivity and extended cycle life. This work provides insights into the mechanism of enhanced cycling stability of aniline oligomers, indicating design features for aniline oligomer electrode materials to improve their electrochemical performance. The mechanism behind the cycling stability of aniline trimer‐based electrode materials is systematically explored. Physicochemical and electrochemical characterizations carried out at pre‐cycling and post‐cycling states reveal that the covalent linkages between aniline trimers and carbon nanotubes as well as the high porosity of the electrode material contribute to the improvement of long‐term cycling stability.