Enhancement of Compressive Strength of Perovskite Foams Used for Thermochemical Energy Storage

Abstract

Reticulated Porous Ceramics (RPCs), also known as ceramic foams are widely investigated for applications in Concentrated Solar Energy (CSE) harvesting, transformation, and storage. However, their inherent shape-related advantages - such as high gas-solid contact area and accommodation of high gas flow rates combined with low pressure drop due to their “open”, thin-struts-structure - are accompanied by low mechanical strength, which hinders large-scale, on-field applications. Foams prepared by the replica method - i.e. via impregnation of “sacrificial” polyurethane (PU) foam templates - exhibit hollow struts of about 100 µm thickness, which limit further their mechanical properties. In this work, an infiltration technique is presented that fills the hollow struts and substantially increases the mechanical strength of such RPC foam structures made of Ca_0.9Sr_0.1MnO₃ (CS10MO), a perovskite composition already identified as very promising for thermochemical storage of CSE. The developed infiltration technique achieves high degrees of infiltration and leads to a substantial increase of mechanical strength, specifically a 217% increase in withstandable compressive stress, from 0.23 MPa to 0.50 MPa. The results show that infiltration of hollow RPC foams can drastically increase the mechanical strength of prepared foam samples, not only making the open porous components for thermal storage devices more rigid and stable, but also increasing the envelope density by adding weight to the component within the same volume. Thereby, the applied infiltration simultaneously increases stability and volumetric storage density of a storage unit that utilizes such open porous foams.