Microwave Synthesis Methods for Lithium-Ion Battery Cathodes

With the rapidly expanding market for mobile devices such as mobile phones, laptops and cameras, as well as the push towards greener, more renewable energy sources, rechargeable batteries have been brought to the fore. With the many uses of lithium-ion batteries from high drain appliances to power storage, to vehicle propulsion, varying

cathodes are required to provide these differing functionalities.

This thesis contains a comprehensive literature review, outlining the history of secondary batteries, their uses, current technologies and ongoing research topics within the field of lithium-ion battery cathodes.

Bronze-phase vanadium dioxide, VO2(B), is a very promising cathode material, with higher theoretical capacity than the current commercial lithium cobalt oxide, LiCoO2. Current synthesis techniques for VO2(B) utilise solvothermal synthesis in a Teflon-lined Parr bomb, which is then placed in an oven for 48 hours. Microwave-assisted synthesis had never before been used for VO2(B), but through its use the reaction time for formation has been significantly reduced.

VO2(B) was also characterised through the use of X-ray absorption spectroscopy whilst undergoing a discharge cycle at the Diamond Synchrotron near Oxford, the first experiment of this kind on VO2(B) using a relatively new battery cell design.

Olivine phosphate structures of iron, manganese and cobalt were also prepared through microwave-assisted synthesis, with lithium iron phosphate being developed as a future electric vehicle battery cathode. These were successfully characterised and cells containing them charge-discharged - the results of these are presented.