The influence of fabrication parameters on the electrochemical performance of multifunctional structural supercapacitors

A critical review of structural supercapacitors and outlook on future research challenges

“…Using EMIMTFSI, this supercapacitor with WCF/CAG achieved a capacitance of 1.73 F/g (normalised by device mass) [22], whilst for a structural electrolyte (PEGDGE/EMIMTFSI), capacitances up to 603 mF/g are reported [47]. WCF/CAG electrodes with epoxy/EMIMTFSI and a polyester/ceramic veil separator gave a capacitance (normalised by device mass) of 1120 mF/g [58]. CAG has a Young's modulus of 25 GPa [59], thus providing improved load-transfer between the fibres for soft matrices, enhancing Fig.…”

“…An alternative route for improving electrode surface area has been to fill as much of the matrix space as possible with a carbon aerogel (CAG) (Fig. 3h), which is achieved by infusion of the WCF with a polymer precursor, followed by pyrolysis [22,47,50,[56][57][58]. Using EMIMTFSI, this supercapacitor with WCF/CAG achieved a capacitance of 1.73 F/g (normalised by device mass) [22], whilst for a structural electrolyte (PEGDGE/EMIMTFSI), capacitances up to 603 mF/g are reported [47].…”

“…Cellulose or other filter papers are a common alternative [35,36,43,60,129], but have an inferior electrochemical performance compared to other separators, perhaps due to their pores being blocked by the structural phase of the electrolyte [29]. Glass fibre fabric separators are widely used: they contribute meaningful structural performance and permit ion transport [6,25,29,34,37,39,41,44,45,47,50,53,57,58,130]. The weave thickness is inversely proportional to the equivalent series resistance (ESR) [130] but if it is too thin, the sparse tow spacing can lead to shorting.…”

High-Performance Multifunctional Structural Supercapacitors Based on In Situ and Ex Situ Activated-Carbon-Coated Carbon Fiber Electrodes

“…14−17 The limitation of the electrochemical properties of these devices may be caused by the instability and vulnerability of the synthesized active materials, and these active materials were easily damaged by the electrolyte matrix during the preparation of structural supercapacitor devices. 16 (3) Formation of carbon fibers in the carbon aerogel (CAG) network: 18,19 Qian et al prepared the CAG-modified structural supercapacitors with a specific capacitance and shear modulus of 71.2 mF/g and 0.28 GPa. 17,18 The CAG network could increase the interaction between electrodes and the electrolyte matrix to improve the mechanical properties of the devices, but the electrochemical properties were still limited by the quality of the CAG synthesized on carbon fiber electrodes.…”

“…(2) In situ synthesis of active materials on the surface of carbon fiber, such as metal oxide nanowires, carbon nanotubes (CNTs), graphene nanoflakes (GCFs), or vertical graphene/MnO 2 : Although the electrochemical properties of these structural supercapacitors have been improved (specific capacitances of most devices were ranging from 10 to 500 mF/g), they were still 2–3 orders of magnitude lower than conventional supercapacitors. − The limitation of the electrochemical properties of these devices may be caused by the instability and vulnerability of the synthesized active materials, and these active materials were easily damaged by the electrolyte matrix during the preparation of structural supercapacitor devices . (3) Formation of carbon fibers in the carbon aerogel (CAG) network: , Qian et al prepared the CAG-modified structural supercapacitors with a specific capacitance and shear modulus of 71.2 mF/g and 0.28 GPa. , The CAG network could increase the interaction between electrodes and the electrolyte matrix to improve the mechanical properties of the devices, but the electrochemical properties were still limited by the quality of the CAG synthesized on carbon fiber electrodes. , In addition, these methods are difficult to achieve large-scale industrial production because of the complex modification process for carbon fibers and high cost of active materials. ,, Also, in the published structural supercapacitor systems, the area of most of the devices was ranging from 15 to 100 cm 2 , ,, which could not represent the electrochemical properties of scale-up devices that have higher requirements on the current collection and preparation process.…”