Advanced Capacitors for Energy Storage (ACES)

Motivation
Energy storage systems play an important role in the sustainable energy program worldwide as they enable more efficient use of energy generated, which in turn, supports the stabilization of energy market and reduces the environment impact. Efficient power conversion and management is essential for the operation of hybrid and electric vehicles (HEV), with automotive power electronics representing an emerging £40 billion global market. Current technology requires cooling of the power electronics because of limitations in the temperature rating of the components, particularly capacitors. Today’s capacitors in HEV employ electrolytic-based capacitors which cannot tolerate temperatures usually above 70 °C and voltages above 450 V and suffer from short lifetime. This is a major limitation to HEV, as it requires capacitors to operate up to 600 V and temperatures up to 140 °C.
Aims
This project aims to develop a new generation of high temperature stability, high energy density lead-free capacitors that will enable power electronics to operate at significantly higher temperatures (up to or above 200 °C). This will be achieved as follows:
• Develop and optimize high energy density thin film compositions with high temperature stability up to 200 °C with low loss and low leakage.
• Process ceramics of the developed compositions and optimize their energy density, loss and leakage properties.
• Develop scaleable processes for high energy density ceramics.
• Produce capacitors based on the selected composition and evaluate part properties.
Impact:
New high temperature and energy density capacitors would support the fast development of HEV and energy harvesting sector and thus reduce the greenhouse gas emissions. As well as the market for automotive power converters major opportunities also exist for high temperature, high energy density lead-free capacitors for emerging pulsed power applications and high voltage capacitors. General electronics applications would also benefit from a reduction in size through improved energy / capacitance density and reduced voltage coefficient of capacitance.