Vapour deposited coatings for long cycle-life Li-ion positive electrodes

Description

The positive electrode (or cathode) represents one of the greatest barriers to increasing the energy density of lithium-ion batteries. The PhD project will involve the use of atomic layer deposition (ALD) to stabilise the interface of candidate cathode materials.

Layered O-redox cathodes, such as Li[Li0.2Ni0.2Mn0.6]O2, exhibit 1st charge capacities of 270-300 mAhg-1 associated with oxidation of Ni2+ to Ni4+ and partial oxidation of O2-. The extra capacity associated with O-redox cannot be fully exploited in practical battery systems due to oxygen loss and side reactions with the electrolyte, as well as transition metal dissolution reactions.

One way to mitigate the increased surface reactivity of O-redox cathodes, high-voltage cathodes, and Ni rich cathodes is to treat the powder materials with an electrochemically inert coating such as SiO2 or Al2O3 of nanoscale thickness. ALD is a modified version of chemical vapour deposition, which can deposit inorganic films onto powders in a sequential manner. This approach allows for precise control of deposited film thickness and composition. The premise of ALD is to adapt CVD based processes by separating a homogeneous gas-phase reaction into binary, tertiary or quaternary surface-mediated reactions. ALD offers a precise control of layer thickness ranging from <1nm to >100nm (process time dependant), enabling complete conformal coating of high surface area materials, such as powders. Coating material stoichiometry can be carefully controlled through changing process parameters and coatings can be conducted under inert, reduced pressure atmosphere. Oxide films will provide protection from electrolyte contact, suppression of electrolyte decomposition (oxidation) upon the electrode surface, as well as stabilisation of surface reactions, conductivity enhancement.

The PhD project will use ALD to synthesise coated battery-grade materials developed and used within the Faraday Institution CATMAT programme. The student will develop novel processes of coating powders, characterising (XPS and low energy ion scattering) them and electrochemical testing.

The PhD project will collaborate with the industrial partners and industrial catapults. The PhD student will have the opportunity for site and lab visits and to discuss methods of scalability of certain processes.

Supervisory team: Laurence Hardwick (Chemistry), Matt Rosseinsky (Chemistry), Paul Chalker (Engineering)

Applications are encouraged from highly motivated candidates who have, or expect to have, at least a 2:1 degree or equivalent in Chemistry or Materials Science.

Applications should be made as soon as possible, but no later than 1st June 2020. Informal enquiries are also encouraged and should be addressed to Professor Laurence Hardwick hardwick@liverpool.ac.uk

Some teaching duties may be required.

The University of Liverpool is committed in its pursuit of academic excellence to equality of opportunity and to a pro-active and inclusive approach to equality, which supports and encourages all under-represented groups, promotes an inclusive culture, and values diversity.

Availability

Open to EU/UK applicants

Funding information

Funded studentship

The Faraday Institution Cluster PhD researchers receive an enhanced stipend over and above the standard EPSRC offer. The total annual stipend is approximately £20,000 plus an additional £7,000 annually to cover training and travel costs. Recipients will have access to multiple networking opportunities, industry visits, mentorship, internships, as well as quality experiences that will further develop knowledge, skills, and aspirations https://faraday.ac.uk/education-skills/phd-researchers/.

In order to apply for a Faraday Institution PhD position, you need to do both of the following:

1. Complete a Faraday Institution expression of interest form https://www.surveymonkey.co.uk/r/9B8V3NB

2. Follow the university application process as per advert

Please quote Studentship Reference: CCPR001 in the Finance Section of the Application Form.

Supervisors

References

Stabilization of O-O bonds by d0 cations in Li4+xNi1-xWO6 (0≤ x≤ 0.25) rocksalt oxides as the origin of large voltage hysteresis
Z.N. Taylor, A.J. Perez, J.A. Coca-Clemente, F. Braga, N.E. Drewett, M.J. Pitcher, W.J. Thomas, M.S. Dyer, C. Collins, M. Zanella, T. Johnson, S. Day, C. Tang, V.R. Dhanak, J.B. Claridge, L.J. Hardwick and M.J. Rosseinsky
J. Am. Chem. Soc.,
 141 18 (2019), 7333- 7346

Some recent developments in the chemical vapour deposition of electroceramic oxides

A. C. Jones, ,  P. R. Chalker

  1. Phys. D-Appl. Phys. (2003) 36, R80-R95

 

Lithium transport in Li4.4M0.4M’0.6S4 (M= Al3+, Ga3+ and M’= Ge4+, Sn4+): Combined crystallographic, conductivity, solid state NMR and computational studies 
B, T. Leube, K, K. Inglis, E. Carrington, P. M. Sharp, J. F. Shin, A. R. Neale, T. D. Manning, M. J. Pitcher, L. J. Hardwick, M. S. Dyer, F. Blanc, J. B. Claridge, and M. J. Rosseinsky
Chem. Matter., 30 (2018), 7183-7200