Rechargeable batteries have a vital role to play in sustainably meeting the energy needs of an expanding population, by storing the energy generated by intermittent renewable sources for when it is needed, and in powering the electric vehicles of the future. However current Li-ion batteries fall well below expectations, suffering from capacity fade during repeated cycling as a result of side reactions occurring at the interfaces between the electrodes and electrolyte. To improve capacity retention we must understand these reactions and how they can be supressed. This studentship focuses on developing multi-modal, operando techniques to reveal the chemistry and structure of interfaces between a battery electrode and the liquid electrolyte during charging and discharging. Reaction environments will be developed that closely resemble the conditions in working Li-ion batteries, but allow the electrode-electrolyte interface to be observed using X-rays and neutrons. X-ray absorption spectroscopy will reveal the chemical environment at the electrode surface, and how the electrolyte decomposes to form a protective layer known as the solid-electrolyte interphase (SEI). Neutron reflectometry will detect variation in the thickness and composition of this SEI. This will reveal the chemistry and structure of the SEI whose stability is critical to long cycle life in Li-ion batteries. Combinatorial effects will be investigated in full batteries, including the role played by metal ions that dissolve from the cathode into the electrolyte and may promote breakdown of the anode SEI, as well as the effect of electrolyte additives on the chemical structure of the SEI formed on high-capacity silicon anodes. This will inform the rational design of the SEI to suppress unwanted side reactions whilst accommodating the large volume changes associated with silicon. The new capabilities developed will be valuable to the study of a broad range of electrochemical phenomena at interfaces.
The project will be based at the Harwell campus for its duration. This is the UK’s leading science innovation and technology campus situated 20 minutes from Oxford and one hour from London. You will be embedded in Dr. Robert Weatherup’s research group within the University of Manchester at Harwell, co-supervised by Dr. Dave Grinter and Prof. Georg Held at B07 beamline (Diamond Light Source) and Dr. Jos Cooper at the OFFSPEC reflectometer (ISIS). You will have access to the world-class research facilities on site and be provided with in-depth training in a range of experimental techniques including X-ray absorption spectroscopy, neutron reflectometry, electrochemical impedance spectroscopy, mass spectrometry, and associated analysis methods. You will also gain experience in electrode material deposition techniques and Li-ion battery fabrication. Dr Weatherup’s group are involved in ongoing projects with the Faraday Institution, whose HQ is also based on the Harwell campus, providing further opportunities for academic and industrial interaction.
Applicants are expected to hold, or be about to obtain, a good 2:i honours degree (or equivalent) in Chemistry, Physics, Materials Science or a related discipline. Some prior experience in X-ray or neutron techniques is advantageous but not essential.