Redox Poly‐Counterion Doped Conducting Polymers for Pseudocapacitive Energy Storage

作者：Mingyue Zhang, Yu Song, Duo Yang, Zengming Qin, Di Guo, Lijun Bian, Xiaoguang Sang, Xiaoqi Sun, Xiaoxia Liu · 发表于：Advanced Functional Materials · 年份：2020 · DOI：10.1002/adfm.202006203 · 被引用次数：86 · 研究领域：Supercapacitor Materials and Fabrication、Conducting polymers and applications、Advanced battery technologies research

Abstract Conducting polymers (CPs) have been widely studied for electrochemical energy storage. However, the dopants in CPs are often electrochemically inactive, introducing “dead‐weight” to the materials. Moreover, commercial‐level electrode materials with high mass loadings (e.g., >10 mg cm −2 ) often encounter the problems of inferior electrical and ionic conductivity. Here, a redox‐active poly‐counterion doping concept is proposed to improve the electrochemical performance of CPs with ultra‐high mass loadings. As a study prototype, heptamolybdate anion (Mo 7 O 24 6− ) doped polypyrrole (PPy) is synthesized by electro‐polymerization. A 2 mm thick PPy electrode with mass loading of ≈192 mg cm −2 reaches a record‐high areal capacitance of ≈47 F cm −2 , competitive gravimetric capacitance of 235 F g −1 , and volumetric capacitance of 235 F cm −3 . With poly‐counterion doping, the dopants also undergo redox reactions during charge/discharge processes, providing additional capacitance to the electrode. The interaction between polymer chains and the poly‐counterions enhances the electrical conductivity of CPs. Besides, the poly‐counterions with large steric hindrance could act as structural pillars and endow CPs with open structures for facile ion transport. The concept proposed in this work enriches the electrochemistry of CPs and promotes their practical applications.