Fraunhofer Institute for Mechanics of Materials IWM
Methodology
A sustainable energy supply is an essential prerequisite for the transformation of our society from fossil fuels to renewable energies. To achieve this goal, new technologies with higher efficiencies in energy conversion are required. Both the German government's National Hydrogen Strategy and the European Union's Green Deal are aimed at a sustainable and resource-efficient economy and society. The efficiency of energy conversion is crucial for achieving the required energy quantities and even small changes in efficiency can play a dramatic role. We are therefore developing new materials for energy conversion based on capillary suspensions.
In materials science, doping, variation and modification of the chemical composition as well as different processing parameters are the traditional modes of modification in order to influence the properties of materials and components. Recently, however, a wide range of additive manufacturing techniques have been developed that make it possible to design complex geometries in previously inaccessible length scales. For ceramics and powder metallurgy materials, this opens up a range from approximately 100 µm to components in the mm or even cm size range. However, since typical particle sizes are usually in the hundreds of nm to single digit µm range, a design gap between 10 µm and 100 µm leaves no control over the geometry.
Capillary suspensions are the ideal method to close that design gap in the micrometer range. The method enables the control of a particle network in the size range of grain dimensions. As a result, ordered structures from 100 nanometers to 100 micrometers can be created. In combination with additive manufacturing techniques, multi-hierarchical meta-structures are accessible, which enable the control and design of new component geometries. At the Fraunhofer IWM, we have already shown that in combination with functional ceramics, the properties can be dramatically increased. Such approaches can also revolutionize other energy conversion applications. Controlled porous structures are critical for a range of devices, such as porous transport layers in fuel cells and electrolyzers, porous nickel foams for nitrate to ammonia conversion, porous electrodes in lithium-ion batteries and additively manufactured thermoelectric generators.