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

• Published in: Nano energy 2021-03, Vol.81, p.105603, Article 105603
• Main Authors: Li, Meng-Tian, Li, Ya-Ting, Sun, Lu, Xu, Zhi-Bin, Zhao, Yun, Meng, Zi-Hui, Wu, Qin-Pei
• Format: Article
• Language: English
• Subjects: Dehydration; Heat storage; Hydroxide; Kinetics; Thermochemical energy; Thermodynamics
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2020.105603

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. [Display omitted] •Tonset reduces by 76 °C by doping 8 wt% Ce(NO3)3 and 6 wt% LiOH.•Dehydration rate of Mg(OH)2 increases by 222 times at 270 °C.•Heat-storage rate of Mg(OH)2 increases by 92 times at 270 °C.•Activation energy for Mg(OH)2 dehydration decreases by 94.7 kJ/mol (−51%).•Mechanism and kinetic model were elucidated.