Three projects on the materials chemistry and electrochemistry of batteries: lithium-air, all solid state lithium and sodium-ion batteries

1. The materials chemistry and electrochemistry of the lithium-air battery

Energy storage represents one of the major scientific challenges of our time. Pioneering work in Oxford in the 1980s led to the introduction of the lithium-ion battery and the subsequent portable electronics revolution (iPad, mobile phone).

Theoretically the Li-air battery can store more energy than any other device, as such it could revolutionise energy storage. The challenge is to understand the electrochemistry and materials chemistry of the Li-air battery and by advancing the science unlock the door to a practical device. The Li-air battery consists of a lithium metal negative electrode and a porous positive electrode, separated by an organic electrolyte. On discharge, at the positive electrode, O2 is reduced to O22- forming solid Li2O2, which is oxidised on subsequent charging. It is the organic analogue of the oxygen reduction/oxygen evolution reaction in aqueous electrochemistry. The project will involve understanding the electrochemistry of O2 reduction in Li+ containing organic electrolytes to form Li2O2 and its reversal on charging. The use for redox mediators to facilitate the O2 reduction and evolution. The exploration of new electrolyte solutions and their influence of the reversibility of the reaction. The project will use a range of electrochemical, spectroscopic (Raman, FTIR, XPS, in situ mass spec.) and microscopic (AFM, TEM) methods to determine the mechanism of O2 reduction (presence and nature of intermediates e.g. superoxide) and its kinetics. Our aim is not to build devices but to understand the underlying science. We seek highly qualified, ambitious, imaginative, hard-working and self-motivated candidates. Further details may be obtained by contacting simultaneously Dr Erez Cohen at erez.cohen@materials.ox.ac.uk and Zsofia Lazar at zsofia.lazar@materials.ox.ac.uk.

2. Challenges facing all-solid-state batteries

Degredation mechanisms in an all-solid-state Lithium-ion battery

Degradation Mechanisms at the Li10GeP2S12/LiCoO2 Cathode Interface in an All-Solid-State Lithium-Ion Battery

There is increasing worldwide motivation to research and develop all-solid-state batteries in order to achieve better safety, higher energy density, as well as wider operating temperature energy storages, as compared to conventional Li-ion batteries using liquid electrolytes. All solid state batteries consist of a solid electrolyte as the main component, an intercalation cathode, e.g. LiCoO2, and an anode with the ultimate goal of implementing a lithium metal anode. The project will involve advancing the fundamental understanding from material to cell level. Synthesis of new Li+ conducting solid electrolytes and characterisation of their structural, electrochemical, electrical, and mechanical properties will be required. The work will include investigation of phenomena at solid electrode/solid electrolyte interfaces, something that is central to progressing solid state batteries but is not well understood, e.g. charge transfer, parasitic reactions, occurring at the interfaces of the electrolytes with both cathodes and anodes. Further parameters affecting the cycleability of the all-solid-state batteries will need to be identified. A range of characterisation techniques will be used, including X-ray and neutron diffraction, electron microscopy, NMR, Raman and IR spectroscopy, X-ray tomography, as well as several electrochemical techniques such as EIS and cycling. We seek highly qualified, ambitious, imaginative, hard-working and self-motivated candidates. Further details may be obtained by contacting simultaneously Dr Erez Cohen at  erez.cohen@materials.ox.ac.uk and Zsofia Lazar at zsofia.lazar@materials.ox.ac.uk.

3. The materials chemistry and electrochemistry of lithium and sodium-ion batteries

Lithium-ion batteries have revolutionised portable electronics and are now used in electric vehicles. However new generations are required for future applications in transport and storing electricity from renewable sources (wind, wave, solar). Such advances are vital to mitigating climate change. Sodium is more abundant than lithium and so attractive especially for applications on the electricity grid. Lithium and sodium ion batteries both consist of intercalation compounds as the negative and positive electrodes. The charge and discharge involves shuttling Li+ or Na+ ions between the two intercalation hosts (electrodes) across the electrolyte. In the case of Li-ion batteries currently the most common technology is still graphite (anode) and LiCoO2 (cathode). However, the development of increased energy storage in Li ion systems drives research to discover new materials. In the case of Na-ion batteries whilst the principles are analogous to that of the Li-ion battery, as yet there are no preferred candidates as electrodes, which provides excellent motivation for further work.

The project will involve synthesising and characterising a number of Na/Li containing transition metal oxides. This will utilise synthesis methods such as sol-gel, hydrothermal and solid state, characterisation will involve X-ray and Neutron diffraction, solid state NMR, XPS, FTIR, TEM and SEM. Additionally it is important to understand the processes at the interfaces between the intercalation oxides and the organic electrolyte. For such the interfacial studies FTIR, Raman, in situ mass spec and XPS will be the main techniques. We seek highly qualified, ambitious, imaginative, hard-working and self-motivated candidates. Further details may be obtained by contacting simultaneously Dr Erez Cohen at erez.cohen@materials.ox.ac.uk and Zsofia Lazar at zsofia.lazar@materials.ox.ac.uk.

The description above outlines a possible new research project being offered to prospective new postgraduate students.

For full details of all postgraduate research projects available for new students and how to apply, please see postgraduate projects available.

Note that post-doctoral research positions are advertised under "Work with Us"

 

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