Measurements of the Dissociation Heats of Tetrabutylammonium Acetate and Tetrabutylammonium Hydroxide Ionic Semiclathrate Hydrates

Ionic semiclathrate hydrates mainly consist of water typically together with tetrabutylammonium and tetrabutylphosphonium salts. Since ionic semiclathrate hydrates have the large dissociation heat under ambient pressure and temperature conditions, various ionic semiclathrate hydrates have been studied as safety and eco-friendly phase change materials. In this study, tetrabutylammonium acetate hydrates and tetrabutylammonium hydroxide hydrates were proposed as thermal energy storage media for air conditioning and cooling lithium-ion batteries. The dissociation heat, which was a significant thermophysical property to design thermal energy storage systems, were measured at various mass fractions. The largest dissociation heats of tetrabutylammonium acetate hydrates and tetrabutylammonium hydroxide hydrates were 212.9 ± 0.9 kJ⋅kg−1 and 200.4 ± 2.2 kJ⋅kg−1. As a result of the comparison of the dissociation heats of tetrabutylammonium acetate hydrates and tetrabutylammonium hydroxide hydrates with those of other ionic semiclathrate hydrates, it was found that tetrabutylammonium acetate hydrates and tetrabutylammonium hydroxide hydrates had the promising thermophysical properties as thermal energy storage media for air conditioning and cooling lithium-ion batteries, respectively.