Large‐Area, All‐Solid, and Flexible Electric Double Layer Capacitors Based on CNT Fiber Electrodes and Polymer Electrolytes

Abstract

This work presents a scalable method to produce robust all-solid electric double layer capacitors (EDLCs), compatible with roll-to-roll processes and structural laminate composite fabrication. It consists in sandwiching and pressing an ionic liquid (IL) based polymer electrolyte membrane between two CNT fiber sheet electrodes at room temperature, and laminating with ordinary plastic film. This fabrication method is demonstrated by assembling large area devices of up to 100 cm 2 with electrodes fabricated in-house, as well as with commercial CNT fiber sheets. Free-standing flexible devices operating at 3.5 V exhibited 28 F g -1 of specific capacitance, 11.4 Wh kg -1 of energy density and 46 kW kg -1 of power density. These values are nearly identical to control samples with pure ionic liquid. The solid EDLC could be repeatedly bent and folded 180° without degradation of their properties, with a reversible 25% increase in energy density in the bent state. Devices produced using CNT

Gas-Phase Functionalization of Macroscopic Carbon Nanotube Fiber Assemblies: Reaction Control, Electrochemical Properties, and Use for Flexible Supercapacitors

“…Noting that these capacitive contributions are in series ( 1 = 1 + 1 ), the increase in CQ makes it less accessible, making the electrostatic component of capacitance corresponding to formation of electric-double layer (CEDL) more dominant and hence reducing the dependence of total capacitance on electrochemical potential. Finally, we use functionalized CNTFs to assemble all-solid supercapacitor devices with a polymer electrolyte, following the method described before 62 . Briefly, the process consists of pressing together a sandwich structure of two CNTF electrodes and a membrane of PVDF-HPF and PYR14TFSI, without need for a separator.…”

Conductive Hydrogels as Smart Materials for Flexible Electronic Devices

“…For example, ah ighly flexible solid-states upercapacitorb ased on ag raphene/polypyrrole hydrogel with long cycle performance was prepared by as imple heating approach. [35] The graphene/polypyrrole hydrogel electrode had superior capacitive performance and excellent cycles tability. The superior performance of the device demonstrated that hybrid hydrogel has ap romising future for applications in wearable supercapacitors.…”

“…Therefore, they exhibit elevated capacitance than electrical double‐layer capacitors and better cycling stability than pseudocapacitors. For example, a highly flexible solid‐state supercapacitor based on a graphene/polypyrrole hydrogel with long cycle performance was prepared by a simple heating approach . The graphene/polypyrrole hydrogel electrode had superior capacitive performance and excellent cycle stability.…”

“…In addition, hydrogel materials have remarkable biological characteristics (such as self‐healing, self‐adhesive, anti‐microbial activity and biocompatibility) to fulfill special demands . Therefore, in recent years, conductive hydrogels have been an active field of research flexible electronics present promising possibilities for flexible electrodes, flexible mechanical sensors, flexible displays and other devices with the human body . For example, flexible sensors can serve as the wearable health monitoring smart system for real‐time tracking of physiological signals in humans.…”

“…[27][28][29][30][31][32][33][34] Therefore, in recent years, conductive hy-drogelsh ave been an active field of research flexible electronics present promising possibilities for flexible electrodes, flexible mechanicals ensors, flexible displays and other devices with the human body. [35][36][37][38][39][40] For example, flexible sensors can serve as the wearable health monitoring smart system for realtime tracking of physiological signals in humans.F or the realization of the conductive-hydrogel-based flexible electronics, the most important consideration is the development of conductive hydrogel materials that support high carrier mobility and good overall electrical performance, together with mechanical and environmental stability.M aterials, including conductive polymers, metals nanoparticles/nanowires, carbonbased materials have been used and investigated as electrochemicala ctive materials for fabrication of various conductive hydrogels. [41][42][43][44][45][46][47][48] Recent works have reporteds ignificanta dvances in hydrogels with unique electronic and mechanicalp roperties.V arious strategies are availablet hat enable the mixture of electronicc onductive ingredients with hydrogel matrixes.…”