Stewart studied for his MChem Chemistry with a Year in Industry at the University in Bath, graduating in 2015 with first-class honours. For his year in industry, he worked within the defence industry as an analytical chemist in gas and vapour chemistry, developing new GC methods to simultaneously analyse organic vapours and atmospheric gases. During his final year under the supervision of Professor Mark Weller he gained an interest in energy materials, with his final dissertation investigating the use of hydrothermal synthesis for fluorophosphate and fluorosulphate materials as solid-state electrolytes in rechargeable-ion batteries, gaining invaluable experience in single crystal and powder XRD techniques.
In 2015, Stewart began his PhD research in to electrode materials and molten salt electrolytes for use in high-temperature batteries. The field is currently dominated by Li-ion alone, but the Li13Si4/MS2 (M=Fe, Co) cells used are susceptible to thermal runaway over temperatures of 600°C and the metal sulphides show dissolution in to the molten electrolyte under 600°C, hence limiting their power and possible applications.