Mechanical Behaviour of solid state lithium ion batteries
Developing a solid state lithium ion battery would have a transformative impact on energy storage, particularly in the area of personal transport, especially if it can be combined with a metallic lithium anode. This would facilitate increased distances through increased energy densities, and improved safety through the removal of the reactive liquid electrolytes. Whilst there are a large range of materials systems being studied and many different cell and battery architectures under development, deployment of these is hampered by a need for fundamental understanding of the mechanical properties of the materials. This is of utmost importance as the anode, cathode and electrolyte are by necessity in contact in a solid state battery as the system charges and discharges stresses are developed and the microstructure evolves and eventually these limit the system lifetimes.
This project will develop a fundamental understanding of the mechanical properties of the ceramic lithium ion conductors such as Li1.4Al0.4Ge1.6(PO4)3 (LAGP) and Li7La3Zr2O12 (LLZO) which have been shown to be promising electrolyte materials for solid state lithium ion batteries. While their electrochemical properties have been well studied there is comparatively little information on the mechanical properties of these materials. This will be followed by measuring the interfacial mechanical behaviour of these materials in contact with both anode and cathode materials. The data produced in this way will not only be useful for seeding mechanical models of cells and batteries but also allow optimisation of processing routes for producing electrolytes with improved lifetimes.
This project will use a range of nano and mico-mechanical indentation methods to study the hardness, elastic modulus, yield stress and fracture toughness of both materials. These properties will be related to local microstructural features through the use of scanning electron microscopy (SEM), electron back scattered diffraction (EBSD) and Raman spectroscopy. In particular a newly commissioned pico-indenter in an SEM integrated glove box will allow testing of reactive materials such as LLZO and lithium without exposure to the air. This system is globally unique and has been funded by both the Faraday Institution and Royce Institute with which this project will interact.
This project would suit a graduate with a background in materials science or engineering with a strong and demonstrable interest in working on the integration of mechanical testing, materials processing and electrochemistry.
Any questions concerning the project can be addressed to Professor David Armstrong ([Email Address Removed]) or Professor Peter Bruce ([Email Address Removed]). General enquiries on how to apply can be made by e mail to [Email Address Removed]. You must complete the standard Oxford University Application for Graduate Studies. Further information and an electronic copy of the application form can be found at http://www.ox.ac.uk/admissions/postgraduate_courses/apply/index.html.
This EPSRC-funded 3.5 year DPhil in Materials DTP studentship will provide full fees and maintenance for a student with home fee status (this status includes an EU student who has spent the previous three years (or more) in the UK undertaking undergraduate study). Candidates with EU fee status are eligible for a fees-only award, but normally would have to provide funding for their living costs from another source such as personal funds or a scholarship. The stipend will be approximately £15,777 per year. Information on fee status can be found at http://www.ox.ac.uk/admissions/graduate/fees-and-funding/fees-and-other-charges .