Composite sorbents "calcium chloride inside alumina and carbon mesopores" for thermochemical energy storage

Thermochemical energy storage is an emerging technology aiming to mitigate the mismatch between heat supply and demand. Adsorption method, which belongs to the wider class of thermochemical energy storage, is a promising solution for storage of low-temperature heat (below 100 °С). Designing efficient energy storage units requires the appropriate choice of the working pair. In this article, we address the properties of composite sorbents 'CaCl2 inside alumina and carbon mesopores', two commercial matrices with similar pore structure, but very different chemical nature and hydrophilicity. Despite this, water sorption equilibrium for both composites are very similar; the composites' sorption properties are influenced more by the confined salt and the matrix' porous structure than by its chemical nature. This finding provides deeper insight into the adsorption mechanisms and can guide designing new advanced composites 'salt in a porous matrix' for various applications. High heat storage density (1.1–1.3 GJ/m3), low regeneration temperature (60–100 ℃), high heat release temperature (up to 60–80 ℃), good hydrothermal stability, and commercial availability of the components make the new CaCl2/Alumina composite very competitive with other materials for thermochemical energy storage.