Three projects on the materials chemistry and electrochemistry of batteries: lithium-air, all solid state lithium and sodium-ion batteries
Energy storage represents one of the major scientific challenges of our time. Pioneering work in Oxford in 1980 led to the introduction of the lithium-ion battery, which made a range of new portable electronics possible. As we move to greener energy, storage is more important than ever and will play a central role in the electrification of transport. To achieve this we need to look beyond the current state-of-the-art to new materials and devices.
1. The materials chemistry and electrochemistry of the lithium-air battery
Theoretically the Li-air battery can store more energy than any other device, as such it could revolutionise energy storage. However, there are a number of issues that need to be overcome before its full potential can be realised. 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.
This project will involve understanding the electrochemistry of O2 reduction in Li+ containing organic electrolytes to form Li2O2 and its reversal on charging, the use of redox mediators to facilitate the O2 reduction and evolution, and the exploration of new electrolyte solutions and their influence of the reversibility of the reaction.
You will use a range of electrochemical, spectroscopic (Raman, FTIR, XPS, in situ mass spec.) and microscopic (AFM, TEM) methods to determine mechanisms and investigate the kinetics. Our aim is to understand the underlying science and use this knowledge to unlock the potential of Li-air. We seek highly qualified, ambitious, imaginative, hard-working and self-motivated candidates. Further details may be obtained by contacting Dr Paul Adamson (email@example.com).
2. Challenges facing all-solid-state batteries
Conventional Li ion batteries contain a flammable liquid electrolyte. Replacing the liquid with a solid, enabling the use of a metal anode, will offer higher energy densities and improved safety. However there are a number of challenges that must be tackled and to do this we need to understand the fundamental processes taking place in these cells.
All solid state batteries consist of a solid electrolyte, an intercalation cathode, e.g. LiCoO2 or NMC, and an anode with the ultimate goal of this being lithium metal. At the anode, stripping and plating of Li results in void formation and dendrite growth which ultimately lead to cell failure. On the cathode side, expansion and contraction during cycling causes contact loss and rapid capacity fade.
This project will involve developing an understanding of the fundamental science at the material and cell level, for example materials synthesis and characterisation of structural, electrochemical and materials properties. This will also include investigation of solid electrolyte-electrode interfaces, an important topic in advancing solid-state battery technology.
You will use a range of characterisation techniques, including electrochemistry, microscopy, diffraction, tomography, NMR, XPS and Raman spectroscopy. We seek highly qualified, ambitious, imaginative, hard-working and self-motivated candidates. Further details may be obtained by contacting Dr Paul Adamson (firstname.lastname@example.org).
3. The materials chemistry and electrochemistry of lithium and sodium-ion batteries
Lithium-ion batteries revolutionised portable electronics and are now playing an important part in an increasing number of technologies, including the electrification of transport. The cathode represents one of the greatest barriers to increasing the energy density and meeting this demand will require new materials.
In current cathode materials, many of which are layered transitional metal oxides, removal of Li during charging is charge compensated by the oxidation of transition metals – limiting energy density. A new class of high voltage cathode materials which store charge on both the transition metals and oxide anions (anionic redox) have the potential to increase energy density by 50%. Several problems have prevented their practical application, including oxygen loss, slow kinetics and structural instability. Li ion is a widely use technology but Na ion is a lower cost alternative due to the greater abundance of sodium.
This project will explore novel cathode materials for use in Li and Na ion batteries. This will involve the synthesis and characterisation of structural, electrochemical and electronic properties to understand the fundamental science underpinning their operation.
You will synthesise Li/Na-containing transition metal oxides using solid state, sol-gel, hydrothermal, and co-precipitation synthesis methods. You will use a range characterisation to study these materials and their operation in cells, for example X-ray and neutron diffraction, NMR, XAS and RIXS. You will also use a number of operando techniques to study changes during cycling. We seek highly qualified, ambitious, imaginative, hard-working and self-motivated candidates. Further details may be obtained by contacting Dr Paul Adamson (email@example.com).
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.
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