Electrochemical carbon nanotube synthesis for application in lithium-ion batteries

About the Project

The goal is to evaluate the benefit of adding multi-walled carbon nanotubes (MWCNTs), synthesised electrochemically in-house from CO2 to anodes and cathodes of lithium-ion batteries. This project combines the expertise of Dr A. Hankin in synthesising MWCNTs via high temperature molten metal oxide/carbonate electrolysis and of Prof M. Titirici in developing and testing new battery chemistries. Hence, CO2 reduction will effectively feed into the development of more sustainable and lower cost energy storage systems, contributing to the net zero transition.

In lithium-ion batteries, the conventional anode material is graphite, and the conventional cathode material is carbon black (as an additive to lithium metal oxides). Carbon nanotubes, which are usually incorporated into materials to improve their properties, can act as an alternative anode material and/or a cathode additive. The principal benefits of CNT inclusion in lithium-ion batteries are: (i) a decrease in the required amount of carbon black, which has a limited supply chain, (ii) decrease in battery weight, (iii) achievement of higher specific capacity and (iv) elimination of chemical binders.

Unfortunately, applications of CNTs in batteries are presently limited by the high cost of conventional CNT synthesis from natural gas by chemical vapour deposition, which is of course also accompanied by release of CO2 off-gas. However, we have been developing a scalable process for simultaneously capturing CO2 and converting it to high-value carbon nanotubes via molten carbonate electrolysis, a process which is 50 times less energy intensive than chemical vapour deposition. Our experimental rig has successfully produced a variety of MWCNT structures.

We propose to couple the CNT synthesis work with the development of more sustainable batteries by M. Titirici to achieve reductions in CO2 emissions and mitigate climate change. If an improvement in battery sustainability can be achieved indirectly through decreased energy requirements for CNT manufacture AND with efficient and profitable CO2 capture and conversion, then this would constitute a crucial technological development.

Research opportunity and project objectives. The feasibility of molten carbonate electrolysis has already been demonstrated thermodynamically and experimentally by others - the fundamental principle has been patented. It is currently at TRL 6 (https://carboncorp.org/). Unhelpfully, there is a shortage of published kinetic data and absence of thermo-kinetic models, multi-physics models or reported strategies for how to model and engineer up-scaled prototypes. We are addressing these aspects systematically in the Hankin lab, with scope for intellectual property generation, and have already synthesised carbon nanotubes and developed an initial reactor design using which we can rapidly produce carbon nanostructures. The further scientific and engineering challenges we are aiming to solve:

(a) Development of an in-depth understanding of how to control the kinetics of carbon electrodeposition to achieve high selectivity in one type of carbon nanostructure (e.g. nanotube, nanofiber or nano-onion etc) in the Hankin lab, which can then be trialled in lithium-ion battery electrodes in the Titirici lab;

(b) Evaluation and understanding of the effect of different carbon nanostructures on lithium-ion battery anode and cathode performances. This research will be extended to other novel battery chemistries, including Na- and K- ion batteries, leveraging the extensive expertise and technical assistance available through M. Titirici’s research group;

(c) Information from (a) and (b) will enable us to determine the optimum nanostructures and the conditions using which they can be synthesised;

(d) Undertaking of a techno-economic evaluation of employing CO2-derived CNTs instead of CH4-derived CNTs in lithium-ion battery electrodes.

As well as conducting your own research, you will work with a team of researchers, providing support to their projects; and be responsible for maintaining safe working practices.

Applicants are expected to have obtained (or be heading for) a first-class bachelor’s degree or distinction at master’s degree in chemical engineering, chemistry, physics, materials science, electrical engineering or mechanical engineering.

Applicants should also be able to demonstrate excellent written and oral communication skills (https://www.imperial.ac.uk/study/pg/apply/requirements/english), which will be essential in collaborating with industrial partners, and disseminating the results via journal publications.

Applications should be made through the College’s online application system:http://www.imperial.ac.uk/study/pg/apply/how-to-apply/

You are encouraged to discuss this opportunity with Dr. Anna Hankin (anna.hankin@imperial.ac.uk) prior to making a formal application. Please cite ‘CNT PHD’ in the email subject.

Funding Notes

42 months of funding