Hierarchical salt-ceramic composites for efficient thermochemical energy storage

The performance of a hygroscopic salt (MgSO4, xH2O) used for thermochemical energy storage can be vastly enhanced when it is distributed in a host zirconia ceramic matrix presenting adequate, hierarchized porosity. The host materials were fabricated by a combination of additive manufacturing technique (robocasting) with pore-former additions and partial sintering, to obtain a 3-scale porosity (with pore diameters spread over 3 decades from 200 nm to 200 μm). The composites were then obtained by simple infiltration of the host material by aqueous salt solutions. The porosity enabled to maximize the amount of salt stored in the host material and its accessibility to water vapor, resulting in potentially high energy density (up to 420 kWh·m-3), without efficiency loss upon hydration/dehydration cycles.