Exceptionally high energy storage density for seasonal thermochemical energy storage by encapsulation of calcium chloride into hydrophobic nanosilica capsules

Thermochemical energy storage (TCES) in salt hydrates is a promising method for seasonal thermal storage. However, suffer from agglomeration and deliquescence drastically degrading their performance after just few cycles. Here, modified dry water-style preparation methods are developed leakage-free microencapsulation of CaCl2 with hydrophobic fumed silica nanoparticles. Using novel phase inversion method, as little 2 wt% needed complete encapsulation, ensuring exceptionally high gravimetric densities up to 98% pure CaCl2. With temperature lifts 30 °C, volumetric 1.4 GJ/m3 shown be achievable. These values unprecedented cycle-stable sorption TCES materials. Optical microscopy, scanning electron microscopy laser diffraction analysis confirm the encapsulation into capsules volume median diameters ranging 90 210 μm depending on content method. The encapsulated deliquesces lower water vapor pressures than no formation tetrahydrate hexahydrate observed. Despite deliquescence, completely stable at least cycles charge-discharge. Thus, new materials show excellent potential