Tremendous enhancement of heat storage efficiency for Mg(OH)₂-MgO-H₂O thermochemical system with addition of Ce(NO₃)₃ and LiOH

Energy storage technology can help provide renewable energy and is an efficient solution for solar energy use. Metal hydroxides are promising candidates for long-term heat storage that rely on overcoming the intrinsically weak kinetics of dehydration. In this study, we show the excellent heat storage performance of magnesium hydroxide (Mg(OH)₂) doped with cerium nitrate (Ce(NO₃)₃ and lithium hydroxide (LiOH). These additives reduced Mg(OH)₂ dehydration temperatures by 76 °C. The dehydration rate and heat storage rate of Mg(OH)₂ at 270 °C notably increases by factors of 222 and 92, respectively. The activation energy of the dehydration reaction is decreased from 184.7 to 90.0 kJ/mol (51%) and pre-exponential factor lnA is reduced by 50%. We also derived and examined the dehydration mechanism functions and kinetic control equation. This study demonstrated the excellent reversibility of the dehydration–hydration cycle for heat storage, meaning that these Mg(OH)₂-Ce(NO₃)₃-LiOH composites are promising heat storage materials.