Probing the chemical degradation of cathode material interfaces in Li-ion Batteries

For future generations of lithium ion batteries to be implemented in electric vehicles, significant improvements in their lifetime and power densities are required.  One of the most important aspects in achieving a long battery lifetime is the stability of the cathode materials (positive electrode).  Over many charge-discharge cycles or when operated under extreme temperatures, undesirable side reactions occur at the surface of these materials such as electrolyte decomposition, transition metal dissolution and gas evolution.  Current techniques to look at these electrode-electrolyte interfaces must be performed after the battery has been disassembled, due to the major challenge of accessing such buried interfaces.  However, such approaches are unreliable as battery interfaces are usually highly reactive and liable to change during disassembly and transfer to the measurement system.

This DPhil (PhD) project aims to investigate the changes occurring at interfaces between the cathode and electrolyte in Li-ion batteries during operation.  This will make use of novel electrochemical cells that incorporate thin membranes through which hard X-ray photoelectron spectroscopy (HaXPES) and X-ray Absorption Spectroscopy (XAS) can be performed.  This will reveal the reversible and irreversible reactions occurring, such as transition metal dissolution and the subsequent plating of these species onto the anode (negative electrode).  You will be primarily based at the Department of Materials at Oxford, which hosts state of the art facilities for battery assembly and characterisation through the Henry Royce Institute and Faraday Institution.  

This industrially funded project is linked with Johnson Matthey (co-supervisors: Tugce Eralp Erden and Carmen Murphy), and you will also have the opportunity to undertake placements in both the Battery Materials and Advanced Surface Characterisation Groups at Johnson Matthey’s Technology Centre (Sonning Common), where you will receive training in the assembly and electrochemical characterisation of Li-ion batteries, as well as X-ray photoelectron spectroscopy and other surface characterisation methods.  As the project progresses, in situ and operando measurements will be performed at synchrotron facilities, such as the nearby Diamond Light Source and other international facilities.

This is a 4-year EPSRC Industrial CASE studentship in conjunction with Johnson Matthey and will provide full fees and maintenance for a student with Home/Republic of Ireland or Islands fee status.  The stipend will be at least £17,009 per year.  Information on fee status can be found at http://www.ox.ac.uk/admissions/graduate/fees-and-funding/fees-and-other-charges..

Candidates will be considered in the November 2020 admissions field which has an application deadline of 13 November 2020 and, if the studentship is unfilled, in the January 2021 admissions field which has an application deadline of 22 January 2021.  

Any questions concerning the project can be addressed to Professor Robert Weatherup (robert.weatherup@materials.ox.ac.uk).  General enquiries on how to apply can be made by e mail to graduate.studies@materials.ox.ac.uk.  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 https://www.ox.ac.uk/admissions/graduate/applying-to-oxford.

Interfacial degradation reactions in a Li-ion battery

Interfacial degradation reactions in a Li-ion battery

 

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