Ceramic electrolyte design mitigating dendrites and voids at the Li anode

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The demand for energy storage devices has never been greater. Lithium ion batteries have played an important role in the development of portable electronics due to their high energy densities. They are a key technology in enabling the electrification of transport and the move away from the internal combustion engine. In order to support the transition to renewable energy sources and to fully electrify transport, new materials and battery technologies will be needed. For example, solid state electrolytes make the use of a lithium metal anode possible, significantly increasing the energy safety, i.e. extending driving range. However important challenges remain to be solved if practical solid-state batteries with a lithium anode and ceramic electrolyte are to be realised. During cycling of a solid-state battery with a lithium metal anode, lithium metal is plated and stripped. This give rise to challenges at the lithium-solid electrolyte interface: how to mitigate the formation of voids at the interface on discharge (stripping) and how to suppress dendrite formation on charging (plating). We have shown the detrimental effects of voiding and have made important progress in understanding lithium dendrite growth, which ultimately leads to cell failure. This fundamental understanding has raised the possibility of controlling both the surface and bulk morphology of the ceramic electrolyte as a means of suppressing voids and dendrites, crucially at practical current densities and pressures. It is these topics that this studentship will investigate. Firstly, the surface of the solid electrolyte in contact with lithium will be modified to prevent voiding and significantly increase the stripping current density. Secondly new understanding of lithium dendrite penetration will be exploited to control the solid electrolyte morphology to realise higher current densities without dendrite growth and short-circuiting. This will also contribute to the understanding of the mechanics of sulphide-based electrolytes.Controlling the surface and bulk morphology of sulphide-based solid electrolytes and understanding the relationship between these factors and the performance of the lithium anode is scientifically and technically challenging. This project will involve designing and developing new techniques to prepare solid electrolytes with different bulk and surface morphologies, to characterise them and to fabricate cells and investigate their performance. These results will be used to produce optimised morphologies. This project will involve a number of techniques to control the morphology, such as 3D printing, hot pressing, spark plasma sintering and other materials processing methodologies. The electrolytes will be incorporated in electrochemical cells and testing such as cycling and EIS will be will be used to assess changes in performance. Scanning electron microscopy and tomography will provide complementary data.This project falls within the EPSRC Physical Sciences and Energy and decarbonisation research areas.The studentship is funded as part of the Faraday Institution's solid-state battery project, SOLBAT, and will collaborate with the other partners involved in the project. This is a 4-year Faraday Institution Studentship (part of the course fee paid from Oxford Materials funds)