Date: Wednesday 24th of February 2021, 13:30.
Location: Online (MS Teams meeting).
‘Silicon anodes for high capacity next generation lithium-ion batteries’
by Mr Hatem Amli, PhD student at the School of Mathematics and Physics, University of Lincoln, Lincoln, UK.
The potential for transforming lithium-ion batteries and the capabilities of future transport vehicles is a huge one given that the capacity of the battery is key in determining the range the vehicle can travel to prior to charging. Lithium ion battery technology is a promising field for the present time and the next few decades. Its value lies in 100s of millions of portable devices, EV and other form of energy storage systems dependant on this technology. Alternative materials such as silicon are being investigated to be part of the lithium ion battery anode composition. That is due to its high capacity compared to other materials such as graphite. Developing more stable lithium ion batteries involves investigating; the different part of the battery structure. This project investigated the development of silicon anodes for lithium ion batteries, using various techniques and procedures including battery cycling systems, scanning electron microscopy (SEM), Raman spectra and X-ray photoemission spectroscopy (XPS).
The prime focus in this thesis is on silicon anodes due to their ultrahigh capacity and potential for future applications. This is explained via a comprehensive study of silicon, silicon/graphite, and silicon/graphite/BaTiO3 using two different electrolytes. The project used XPS to focus on the development and transformation of materials on the surface of the anode before and after cycling, and correlated these findings with the battery performance. Amongst the findings of this work is the benefit of using BTO in the silicon composite which significantly enhances the performance of the battery compared to pure silicon anode. This is observed through the cycling performances of the synthesised cells. The XPS scans for the enhanced silicon/BTO anode at different cycles provided a novel set of results showing slower degradation of the electrolyte, a more stable cycling performance on the longer cycles, and slower irreversible degree of permanent lithium intercalation on the anode compared to the pure silicon anode.
Finally the Raman spectrum on the other hand shows a strong direct relation with the degree of crystallinity of the silicon nano powders and the capacity of the battery. The higher the degree of crystallinity the better the specific capacity and the columbic efficiency of the battery.