Wet spun single-wall carbon nanotube fibres for structural energy storage devices
File(s)
Author(s)
Balaskandan, Kalpana
Type
Thesis
Abstract
Research in structural energy storage systems or ‘structural power’ is an emerging field, mainly driven by efforts to move towards lighter, more efficient energy storage systems; the approach is particularly relevant for the automotive and aviation industry and the realisation of fully electrified systems. Structural supercapacitor devices incorporate multifunctional components that act as structural scaffolds or reinforcements carrying mechanical load whilst simultaneously storing electrochemical energy. Currently, structural power composites are typically pre-preg laminates that are modified, sacrificing mechanical performance for electrochemical multifunctionality. Alternative electrode/device architectures, for instance based around individual fibres, could offer a promising strategy for high performance structural supercapacitors. In principle, fibre-based electrodes could improve rate performance, through shorter ion diffusion distances, yielding devices with high power densities with the potential to out-perform traditional planar counterparts. Carbon nanotube (CNT) containing fibres are attractive for their promising mechanical properties, combined with high electrical conductivities and large electrochemical surface areas; such fibres could be applied as electrodes for structural supercapacitors.
This thesis presents a promising route to fabricating pristine single walled carbon nanotube (SWCNT) fibres via wet spinning nematic liquid crystal solutions of ultra-long SWCNTs. The wet spun SWCNT fibres produced are mechanically robust, exhibiting strengths ranging from 100–800 MPa (~0.1– 0.3 N tex-1) and high Young’s moduli up to 58 GPa. In aqueous electrolyte, SWCNT fibre electrodes behave as ideal electrical double layer (EDL) capacitors with high capacitance of up to 62 F g-1. In ionic liquid-based systems, the SWCNT fibres electrodes exhibit higher capacitances of up to 89 F g-1; the increase is attributed to better wetting of fibre electrodes and a contribution from quantum capacitance. Finally, a prototype all solid-state fibre-shaped device (FSC) was assembled exhibiting a max. energy density of 3.5 Wh kg-1 and high max. power density of 103.1 kW kg-1.
This thesis presents a promising route to fabricating pristine single walled carbon nanotube (SWCNT) fibres via wet spinning nematic liquid crystal solutions of ultra-long SWCNTs. The wet spun SWCNT fibres produced are mechanically robust, exhibiting strengths ranging from 100–800 MPa (~0.1– 0.3 N tex-1) and high Young’s moduli up to 58 GPa. In aqueous electrolyte, SWCNT fibre electrodes behave as ideal electrical double layer (EDL) capacitors with high capacitance of up to 62 F g-1. In ionic liquid-based systems, the SWCNT fibres electrodes exhibit higher capacitances of up to 89 F g-1; the increase is attributed to better wetting of fibre electrodes and a contribution from quantum capacitance. Finally, a prototype all solid-state fibre-shaped device (FSC) was assembled exhibiting a max. energy density of 3.5 Wh kg-1 and high max. power density of 103.1 kW kg-1.
Version
Open Access
Date Issued
2023-03-16
Date Awarded
2024-03-01
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Shaffer, Milo
Greenhalgh, Emile
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP/P007465/1
Publisher Department
Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)