Robust dielectric charge storage devices offering reliable operation at high voltage and temperature are required for power electronics in renewable energy and for harsh environment electronics. A revolution has already taken place in wide band gap semiconductors, interconnects and high-temperature packaging, allowing operation at temperatures of 300C. Similar breakthroughs have yet to be made in dielectric charge storage technology: overcoming this barrier would advance electronics for power conditioning and conversion, energy storage, aerospace distributed control systems, deep well geothermal energy and defence applications. As well as thermal resilience, the new generation of Class II ceramic capacitors must operate reliably and safely at high voltages, especially important for power and energy storage applications.
The main goal of the project is to advance particle aerosol deposition (AD) as a product development and manufacturing tool for a new generation of capacitors based on novel alkaline earth meta-niobate dielectric ceramics. We will demonstrate single-chamber, multi-nozzle sequential deposition of dielectric and electrode materials, with sophisticated process control to fabricate multilayer structures comprising ceramic, metal and polymer materials. Benign capacitor failure modes will be investigated, exploiting the unique capabilities of AD for room-temperature fabrication and materials integration. The high ceramic densities and 10 nm scale pore sizes attainable by AD, together with an absence of thermally induced ceramic defects (because of our selection of dielectric material and avoidance of high temperature sintering) offers to realise performance levels unattainable from existing materials and manufacturing procedures.
Key components of the project are: continuous particle manufacture using cascade reactors for rapid compositional prototyping of ultrafine powders; jet milling for refinement of particle structure; computational fluid dynamics to support AD process development; experimental optimisation of AD parameters for the new dielectric materials; evaluation of the new capacitors in a power electronic converter. Understanding the interplay between manufacturing conditions and product properties is an essential element of this multidisciplinary project.
Aerosol deposition avoids a range of problems associated with high temperature processing that degrade dielectric ceramic performance. This future manufacturing route is relevant to single layer, mm scale thickness, and multilayer capacitors with > 1 um component layers. Deposition rates in excess of 10 um per min within a scalable manufacturing process offer a solution to the long-standing challenge of integrating a wide range of thermally dissimilar materials. The approach offers exciting possibilities for translatiion into an industrial manufacturing context, bringing advantages to the emergent field of wide band gap semiconductor based electronics.
The project will use the industry-focussed aerosol deposition manufacturing research facility at Manchester University, the first of its kind in the UK, funded by the Henry Royce Institute.