Thermochemical heat storage performances of magnesium sulphate confined in polymer-derived SiOC aerogels

The thermochemical heat storage performances of hygroscopic magnesium sulphate (MgSO4) can be improved by dispersing it within a porous matrix. However, the host material must be able to bear the intense stresses developed by the hydration of the salt. In this work, we report the first use of a polymer-derived SiOC ceramic aerogel as host for the confinement of MgSO4 for seasonal thermal energy storage, providing a way to easily tune its final porosity to achieve controllable mass fractions of salt in the so-obtained composite. Besides, the distinctive mesoporosity of ceramic aerogels guarantee a free path for water vapour to rapidly hydrate MgSO4 while avoiding the breakage of the composite. Vacuum impregnation of the aerogel samples led to a composite with a maximum of 59.1%wt of MgSO4.1 H2O and a complete hydration in 60 min under H2O saturated air. © 2021 Elsevier B.V. All rights reserved.