Metallocene/carbon Hybrids Prepared by a Solution Process for Supercapacitor Applications Accessed Terms of Use Metallocene/carbon Hybrids Prepared by a Solution Process for Supercapacitor Applications

The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Abstract Efficient and scalable solution-based processes are not generally available to integrate well-studied pseudocapacitive materials (i.e., metal oxides and conducting polymers) with other components such as porous carbon, mainly because these classes of pseudocapacitive systems have poor solubilities in solvents and exhibit no specific interactions with the other component. Here we report, for the first time, the integration of a metallocene polymer, polyvinylferrocene (PVF), with carbon nanotubes (CNTs) via a simple solution process for supercapacitor applications. The solution processability of the PVF/CNT hybrid is due to the high solubilities of PVF in organic solvents and the unique ability of the metallocene/carbon system to form stable heterogeneous inks through the π-π stacking interactions between the two components. The nanostructure and electrochemical properties of the hybrid can be manipulated systematically by adjusting the composition of the heterogeneous ink. The hybrid with the optimized composition exhibits unusually high capacitance (1452 F/g) and energy density (128.9 Wh/kg) obtained in a standard two-electrode configuration, outperforming previously reported pseudocapacitive materials. Broader Context Supercapacitors with extremely high capacitance, enhanced energy and power densities, and excellent reliability offer great potential as complements to, and replacements for, batteries and conventional electrolytic capacitors for energy storage applications. Carbon nanomaterials, metal 2 oxides and conducting polymers have been investigated widely as supercapacitor electrode materials. Many emerging high-performance supercapacitor devices benefit from the integration of these different capacitive materials to exploit their synergies for enhanced capacitance and energy density. Meanwhile, solution processing is low-cost, high-throughput, and readily scalable. It is the preferred fabrication method for many devices such as solar cells, transistors, batteries and single-component supercapacitors, but is very difficult to use for the integration of either metal oxides or conducting polymers with other capacitive materials such as carbon nanotubes. Instead, the common integration methods rely for the most part on electrochemical deposition processes, which are time-consuming, low-throughput and difficult to scale up. In this study we have developed a metallocene/carbon hybrid system amenable to solution processing, with control of the nanostructure and electrocapacitive performance of the hybrid materials realized through manipulation of the ink composition. The optimized hybrid system, as determined by its composition, consists of a highly porous nanoscale architecture in which a three-dimensional conductive carbon nanotube network with interconnected nanopores is coated conformally by the redox-active metallocene polymer. This unique …