Ian M. Reaney (IMR, PI) is a Fellow of the Royal Microscopical Society and the IOM3, and Dyson Chair in Ceramics at UoS. He is European Site Director for the US National Science Foundation Centre for Dielectrics and Piezoelectrics.

He has won numerous awards, such as the Verulam Medal (2017) and most recently the Robert E Newnham Award (2021) from the IEEE for structure-property relations in electroceramics. He is a named Investigator on 35 EPSRC grants totalling >£45m with >£8m as PI, including the recent, multi- and interdisciplinary grant (EP/L017563/1, £2.4m) on ‘Substitution and Sustainability in Functional Materials and Devices’ (SUBST) and Transforming the Foundation Industries Network+ (EP/V026402/1, £2.3m). He has >400 publications (>24k citations, h-index=81).

High voltage, temperature and volumetric efficiency capacitors for applications in power electronics

High energy density capacitors that can operate at high voltage and temperature are currently needed to meet the growing demand in the battery management systems of electric vehicles and large-scale energy storage devices. Polymer dielectric capacitors offer high power/energy density for applications at room temperature, but above 100 °C they are unreliable and suffer from dielectric breakdown.

For high-temperature applications, therefore, dielectric ceramics are the only feasible alternative. Lead-based ceramics such as La-doped lead zirconate titanate exhibit good energy storage properties, but their toxicity raises concern over their use in consumer applications, where capacitors are exclusively lead free. Lead-free compositions with superior power density are thus required.

Key factors to improve energy storage properties include control of local structure, phase assemblage, dielectric layer thickness, microstructure, conductivity, and electrical homogeneity through the choice of base systems, dopants, and alloying additions. The current and future requirements for materials in high energy density capacitor applications are discussed.