Monolithic porous perovskite ceramics for hybrid sensible/thermochemical heat storage in air-operated Concentrated Solar Power plants

Abstract

Addressing the materials needs and requirements of next generation concentrated solar thermal (CST) technologies targeted on high-temperature processes for electricity generation and solar thermochemical applications, the present study reports research results on the shaping of porous monolithic structures made entirely out of CaMnO3-based perovskite pow-der compositions. The approach targets on the eventual use of such structures as hybrid sen-sible-thermochemical heat storage media, based on their characteristic capability for cyclic reduction-oxidation (redox) in direct contact with air, accompanied by endother-mal/exothermal heat effects and complete reversibility of oxygen uptake/release and dimen-sional changes due to expansion/contraction. Multi-cation perovskite compositions were syn-thesized by scalable solid-state routes, optimizing the sintering conditions with respect to the desired properties of merit like phase purity of the obtained perovskite, heat capacity, dimen-sional changes due to thermochemical expansion/contraction and absence of reversible, yet detrimental for the thermomechanical strength and longevity of structured ceramics, phase transformations. Subsequently, monolithic porous structures, namely honeycombs and reticu-lated porous ceramics (RPCs) were manufactured out of compositions that exhibited a favor-able combination of the key properties of merit above. Such monolithic structures of a variety of shapes and dimensions were sturdy and rigid enough to be subjected to several post-shaping (ongoing) tests relevant to the targeted hybrid sensible-TCS application.