Abstract:

Carbon Nanotubes have in the past year or so hit it ‘big-time’. Their incorporation, as a powder or suspension additive, into both anodes and cathodes of lithium-ion batteries, has greatly enhanced the battery lifetime. The nanotubes contribute both to the strength and the electrical conductivity of the electrodes. The business is now $B and the newest plant announced is 1000 tonnes/year.But what of fibres? The history of carbon nanotube development will be briefly reviewed, and the three major competing processes compared. The objectives, as far as properties are concerned is to align all nanotubes with the fibre axis and to pack them together as closely as possible. The ability to achieve this perfect objective, depends not only on the quality and uniformity of the nanotubes, but the effectiveness of the fibre spinning process. Much of the first 20 years since the first reports of successful spinning were reported, have been dedicated towards the quest for strength. However, the focus of the talk from this point on will be the emerging science as one investigated a totally new material. Much of the useful framework has been set by the development of artificial polymer fibres, as well as the achievement of order in disordered polymeric systems despite the limitations imposed by entanglements. The really mega market of the future will be for light weight and strong electrical conductors. CNTs have brought electronic properties of graphite to the fore, with the added advantages for minute tubes of superb electron mobility due to the ‘quantum wire effect’ and the realisation that because of abnormally high density of states at the boundaries of the valence bands, it actually makes sense to put electron holes in the valency bands, thus relying on extrinsic semi-conductivity rather than having to make tubes with the helicity that gives metallic conductivity albeit with much lower density of states. And finally, might there be an even better dopant than AlCl4 yet to make the running?