Phase change composite based on protic ionic liquids 2-hydroxyethylammonium lactate and stearic acid for thermal energy storage systems at intermediate temperatures

Abstract

Abstract The incorporation of phase change materials (PCMs) within thermal energy storage (TES) systems represents a pivotal advancement in materials science, enabling the efficient harnessing and deployment of solar energy and waste heat. PCMs based on ionic liquids hold significant importance in various fields and applications due to their unique properties and advantages. The new family of phase change composites based on ionic liquids, (ILs) tris(2-hydroxyethylammonium) lactate ([THEA]La), bis(2-hydroxyethylammonium) lactate ([BHEA]La), and 2-hydroxyethylammonium lactate ([HEA]La) with stearic acid (SA), are presented in this work. These PCMs offer a secure and cost-effective capacity and function between 323 and 423 K. The flexibility to control chemical and phase characteristics, combined with good chemical and thermal stability, give ILs an inherent “green” quality that makes them ideal for PCMs. Using PCM1 ([HEA]La/Sa) the effective latent heat 245 J g−1. The PCM1 ([HEA]La/SA) was obtained according to the results of differential scanning calorimetry method which has a greater heat capacity rather than the other two PCMs. Thermal stability analysis indicates that PCM1 ([HEA]La/SA) has the highest level of stability (97.21%). This study delves deeper into the molecular underpinnings responsible for the impressive thermal energy storage capabilities exhibited by these ionic materials, elucidating their structural intricacies and highlighting the pivotal role of hydrogen bonds in enhancing PCM performance. By adopting this approach, we sidestep the intricacies and expenses associated with composite PCMs, relying instead on readily available and cost-effective materials.