Abstract
Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density. Here we report a high-performance supercapacitor based on polyaniline/vertical-aligned carbon nanotubes (PANI/VA-CNTs) nanocomposite electrodes where the vertical-aligned-structure is formed by the electrochemical-induction (0.75 V). The supercapacitor displays large specific capacitance of 403.3 F g−1, which is 6 times higher than disordered CNTs in HClO4 electrolyte. Additionally, the supercapacitor can also present high specific capacitance (314.6 F g−1), excellent cycling stability (90.2% retention after 3000 cycles at 4 A g−1) and high energy density (98.1 Wh kg−1) in EMIBF4 organic electrolyte. The key to high-performance lies in the vertical-aligned-structure providing direct path channel for ion faster diffusion and high electrochemical capacitance of polyaniline for ion more accommodation.
Highlights
To further improve the capacitive performance, conducting polymers, which were served as electrochemically active materials for pseudo capacitance were introduced in CNTs23–26
In this work, motivated by the combination between the vertical-aligned-structure and electrochemical activity design, we develop a supercapacitor based on PANI/VA-CNTs electrodes in which the vertical-aligned-structure is obtained by a electrochemical induction, and simultaneously the PANI is in-situ grown on the CNTs
When the PANI was electropolymerized on the VA-CNTs backbone, more charges would be accommodated in the electrode through the redox reaction, which further enhanced the electrochemical performance
Summary
To further improve the capacitive performance, conducting polymers, which were served as electrochemically active materials for pseudo capacitance were introduced in CNTs23–26. Lin et al reported PANI incorporated with aligned CNTs electrodes based supercapacitors. The electrochemical performance of supercapacitors was largely enhanced by the useful process of structural and electrochemical design of electrode materials. In this work, motivated by the combination between the vertical-aligned-structure and electrochemical activity design, we develop a supercapacitor based on PANI/VA-CNTs electrodes in which the vertical-aligned-structure is obtained by a electrochemical induction, and simultaneously the PANI is in-situ grown on the CNTs. Owing to the vertical-aligned-structure providing straight and fast ion transport pathchannel, large pseudocapacitance of polyaniline and high electric conductivity, the supercapacitor displays high electrochemical performance, including large specific capacitance, good cycling stability and high energy density. Our work clarifies an important role of structural and electrochemical activity design, which will guide the development of next-generation supercapacitors
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