Structural Supercapacitors with Enhanced Performance Using Carbon Nanotubes and Polyaniline

Abstract

Carbon fiber electrodes for structural supercapacitors were modified to achieve increases in specific capacitance and energy density. In cyclic voltammetry tests with a liquid electrolyte, the specific capacitance of a commercial carbon fiber fabric weave was 0.84 F g −1 or lower, depending on the sweep rate. Impregnation of the carbon fiber with multiwall carbon nanotubes (MWCNT) or electrochemical functionalization of the carbon fiber increased the capacitance to 3 F g −1 . Electrochemical functionalization of the MWCNT-impregnated carbon fiber further increased the capacitance to 7.2 F g −1 . Electrochemical synthesis and deposition of polyaniline on carbon fiber electrodes increased the electrode capacitance to 26 F g −1 . MWCNT and polyaniline were incorporated into structural supercapacitors made of carbon fiber electrodes, glass fiber separator, and poly(ethylene glycol)-based solid polymer electrolyte. Incorporation of MWCNT increased the specific capacitance and energy density 28-fold, to 125 mF g −1 and 17.4 mWh kg −1 , respectively. Mechanical properties were comparable to previously demonstrated structural energy storage devices. Although the specific capacitance of these solid-state supercapacitors was significantly higher than what was previously demonstrated, the energy density, rate capability, and mechanical performance still require significant improvements for multifunctional structural energy storage devices to be competitive with conventional supercapacitors and carbon fiber composites. In multifunctional material systems, two or more functions are performed by the same material, component, or structural unit.1 The goal in the design of such systems is a smaller volume or mass compared to a combination of corresponding monofunctional elements. One of the most common types of multifunctional material systems is structural energy storage, in which a battery, capacitor, or supercapacitor acts as a structural element for the overall system. Various forms of structural energy storage have been described, 2 and these systems have been proposed for application in communications satellites, 3 spacecraft, 4 ground vehicles, 5 and unmanned aerial vehicles (UAV). 6-9Small UAVs are typically powered by rechargeable batteries and are prime candidates for incorporation of a structural battery, for example as part of a wing or fuselage. Incorporation of structural energy storage can theoretically increase the flight endurance time in small UAVs because of the interdependence of the subsystem weights, amount of available energy, and flight endurance. 7,9 Theoretical analysis by our own group predicted as much as 200% increase in flight endurance when structural batteries are fully incorporated into a small UAV. 9Even modest increases in flight time, such as 10% or 20%, would provide significant benefit because missions are often limited to less than an hour endurance.Much of the previous work on structural energy storage has focused on lithium-ion batteries. Some common approaches are to incorporate commerc...

Structural supercapacitors using a solid resin electrolyte with carbonized electrospun cellulose/carbon nanotube electrodes

“…The specific capacitances of CF900 and CF900/CNTs electrodes are calculated to be 0.91 ± 0.02 mF cm -2 (699 ± 15 mF g -1 or 114 ± 3 mF cm -3 ) and 3.35 ± 0.05 mF cm -2 (2573 ± 38 mF g -1 or 419 ± 6 mF cm -3 ), respectively. The values of the capacitance are higher than the multiwall CNTs impregnated carbon fibre-based electrodes reported in a recent study [19] and several times higher compared with the specific capacitance (52 mF g -1 ) for activated carbon fibre electrodes [20]. The large IR drop (a rapid voltage change at the initial stage of the discharge) for both GCD curves indicates that there is large equivalent series resistance (R s ) in the capacitors.…”

Designing Structural Electrochemical Energy Storage Systems: A Perspective on the Role of Device Chemistry

“…Many researchers have developed pseudocapacitors, by coating carbon electrodes with powders or films that can store charge through surface adsorption/desorption of ions, redox reactions with the electrolyte, or doping/undoping of the electrode materials. Modifications to improve pseudocapacitive behavior have included functional groups ( Ganguly et al, 2020 ), conductive polymers ( Benson et al, 2013 ; Liu et al, 2016 ; Shi et al, 2016 ; Hudak et al, 2017 ; Flouda et al, 2019b ; Javaid et al, 2021 ), metal particles ( Mapleback et al, 2020 ), and metal oxides ( Deka et al, 2016 ; Liu et al, 2016 ; Deka et al, 2017b ; Choi et al, 2017 ; Deka et al, 2019 ; Sha et al, 2021 ).…”

A porous MOF-derived NiMn2O4 material and its superior energy storage performance for high-performance supercapacitors

“…Carbon, in its various forms, is currently the most extensively examined and widely utilized electrode material in commercial EDLCs because of its properties, such as excellent mechanical strength, high electron mobility, excellent chemical stability in acidic and basic media, good electrical conductivity, good thermal stability over a wide range of temperatures, various morphological structures, high specific surface area, availability, and low cost. 6,7 In contrast, carbon materials may suffer from relatively restricted specific capacitance. 8 Many researchers have focused on replacing the carbon electrode with redox active materials that exhibit higher capacitance due to their charge storage mechanism.…”