Temperature controlled reversible hydration/dehydration reactions in MgAl-layered double hydroxides for thermochemical energy storage

Abstract

Layered double hydroxides (LDHs) are a structurally versatile class of materials, yet their potential for thermochemical energy storage (TCES) has remained unexplored. In this work, we present the first demonstration of LDHs as thermochemical storage materials operating through reversible hydration/dehydration reactions. The intrinsic structural flexibility of LDHs, composed of alternating layers of mixed divalent and trivalent cations charge-balanced by interlayer anions, may enable fine control over reaction thermodynamics and energy density. Among various cation/anion combinations, Mg/Al-LDH was synthesized and systematically evaluated as a reference material. Comprehensive structural (XRD, Raman, and Al-NMR) and thermal analyses (TGA, DSC, STA-water vapor) revealed good short-term cyclability for at least 40 cycles, with the material exhibiting a pronounced memory effect (reversibility) with an energy density of 532.4 J g⁻¹. These findings establish that layered double hydroxides could establish a promising family of materials for an extended range of temperature conditions in thermochemical heat storage.