PhD Studentship: Further development of the aqueous Al-ion battery currently being pioneered at the

Aluminum-ion (Al-ion) batteries, offer lower cost more abundant electrode materials, higher thermal stability and higher theoretical energy density than lithium-ion batteries. Al-ion batteries are not yet well characterized, with only a few publications, mainly focusing on individual electrodes. Using an aqueous electrolyte offers cost, recycling and chemical handling advantages over other proposed Al-ion chemistries and conventional Li-ion batteries. The project aligns to the Governments Industrial Strategy on New Energy Technologies and will further develop the aqueous Al-ion battery currently being pioneered at the University of Southampton. This is a completely novel system and to progress it beyond bench-scale proof of concept, it is vital to understand the mechanism of charge storage. Once the mechanism is identified, the active materials can then correctly be tailored for intercalation (crystal structure, doping of TiO2) or charge transfer (surface morphology).

The research will follow the below programme:

• The PhD student will be embedded within the Energy Technologies Research Group in the Faculty of Engineering and Physical Sciences at the University of Southampton During their first year they will be given tuition in the fundamentals of electrochemical energy storage. During this time, the student will identify geometric, material and orientation limitations for the ISIS facilities. These parameters will be coupled to the battery performance monitoring requirements to obtain the design specification for the test rig. The student will also work within the Energy Materials group at ISIS to learn about the design and construction of neutron capable sample environment and will apply to the neutron training courses provided by ISIS.
• During the first year, the student will obtain enough working knowledge of the research question to develop a design specification for the test rig and to produce an engineering model for the manufacture of a prototype rig. This rig will allow for the in-situ structural (via neutron diffraction) and electrical characterisation of battery systems. In addition, the rig will allow for electrochemical characterisation during neutron tomography experimentation. In parallel, they will gain an understanding of battery operation parameters in the Electrochemical Engineering Laboratory at Southampton. The rig will specifically include side ports for electrical connections to better assess the state-of-charge, ascertain stable reference potentials, and electrochemical state of charge determination. The side ports can also be used to obtain voltage drop and IR measurements under operational conditions.
• In-situ characterization of the battery cells at ISIS will be complimented by impedance spectroscopy (EIS) and high-resolution X-ray computed tomography at the University of Southampton. EIS will provide state of health (state of charge, side reactions, electrode operation) metrics, while the application of Southampton's muVis x-ray tomography suite to monitor the electrode reaction surface and component thickness/morphology during operation will provide key insights linking active speciation, material geometry and electrochemical behaviour. Housing the battery cells within the test rig will allow correlation of areas of interest between ISIS and Southampton measurements. Once the test rig has been demonstrated with known battery chemistries in CR2032, 18650, 26650 and pouch cell architectures, it can be used to investigate more novel battery chemistries.
• Specific battery investigation to elucidate the mechanism of charge storage in a novel aqueous aluminium-ion battery; Once the prototype has established proof of concept operation, the design will be optimised into the final rig. Extended operational testing of the final design at ISIS will run in year 3 and 4, where the novel aluminium ion battery will be characterised, demonstrating the research benefits of the test rig. The ability to obtain in-situ crystallographic information on the electrode structures will enable the mechanism of charge storage to be determined by differentiating between surface interactions and true Al3+ intercalation. This mechanistic data obtained using the proposed rig will define if the future direction of development will be focussed towards intercalation materials (battery) or surface structures (hybrid supercap).

This PhD project will be funded jointly by the Faraday Institute and STFC. 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.

If you wish to discuss any details of the project informally, please contact Dr Richard Wills, Energy Technology research group, Email: rgaw@soton.ac.uk , Tel: +44 (0) 2380 59 7615