Jorge L. LOPEZ MORALES1, Jonatan PEREZ-ARCE1, Angel SERRANO1, Jean-Luc DAUVERGNE1, Nerea CASADO2,3, David MECERREYES2,3, Elena PALOMO DEL BARRIO1,3, Eduardo J. GARCIA-SUAREZ1,3
1Center for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Vitoria-Gasteiz, Spain
2POLYMAT, University of the Basque Country UPV/EHU, Donostia-San Sebastian, Spain
3IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
The scientific community is untiringly trying to find plausible, ingenious, disruptive and efficient solutions to generate energy and to avoid the evident impact of the global warming on the planet and on living beings. The employment of alternative green and/or sustainable energy sources such as solar, wind, sea, biomass etc., focus most of the efforts and impressive advances have been achieved in last years. Nevertheless, most of the renewable energy is produced discontinuously and/or seasonally due to its dependence on daily weather and/or the climatology. Therefore, its efficient storage still remains a milestone to allow the use of the generated renewable energy under demand. Among the different approaches to storage renewable energy its storage as thermal energy is one of the alternatives that is under constant development. In this regard, phase change materials (PCMs) are able to storage large amounts of energy in form of latent heat and in addition, they can be easily integrated into thermal energy storage (TES) systems. Nevertheless, most of the employed PCMs undergoes solid-liquid transitions which hamper their implementation due to leaking issues and the need of containment increasing undesirable the final cost of the TES system. To avoid these problems a class of PCMs having solid-solid transitions have emerged. Nevertheless, these materials are limited to a series of alcohols and amine derivatives of 2,2-dimethylpropane or their mixtures with paraffins or fatty acids. In addition, these PCMs do not address completely the problem of containment due to associated sublimation problems and incompatibility with the most widely used heat transfer fluid (water). As alternative, the so called organic ionic plastic crystals (OIPCs) have emerged as a plausible solution to mitigate the sublimation as well as the heat transfer fluid compatibility.
In this work, a series of OIPCs formed by the combination of dioctylammonium cation with different organic and inorganic anions have been prepared and characterized by structural and thermo-physical means. In addition, the potential application of these OIPCs as PCMs in TES systems will be discussed.