Department of Materials Science and Engineering, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto, 606-8501, Japan.
Adv Mater. 2017 Jul;29(28). doi: 10.1002/adma.201606569. Epub 2017 Jun 6.
Thermal energy storage based on chemical reactions is a prospective technology for the reduction of fossil-fuel consumption by storing and using waste heat. For widespread application, a critical challenge is to identify appropriate reversible reactions that occur below 250 °C, where abundant low-grade waste heat and solar energy might be available. Here, it is shown that lanthanum sulfate monohydrate La (SO ) ⋅H O undergoes rapid and reversible dehydration/hydration reactions in the temperature range from 50 to 250 °C upon heating/cooling with remarkably small thermal hysteresis (<50 °C), and thus it emerges as a new candidate system for thermal energy storage. Thermogravimetry and X-ray diffraction analyses reveal that the reactions proceed through an unusual mechanism for sulfates: water is removed from, or inserted in La (SO ) ⋅H O with progressive change in hydration number x without phase change. It is also revealed that only a specific structural modification of La (SO ) exhibits this reversible dehydration/hydration behavior.
基于化学反应的热能存储是一种有前途的技术，可通过存储和利用废热来减少化石燃料的消耗。为了广泛应用，一个关键的挑战是确定合适的可逆反应，这些反应要在 250°C 以下发生，因为在这个温度范围内可能有大量的低品位废热和太阳能可用。在这里，研究表明，一水硫酸镧 La(SO4)·H2O 在 50 至 250°C 的温度范围内，通过加热/冷却会发生快速且可逆的脱水/水合反应，且热滞后（<50°C）很小，因此它成为热能存储的新候选系统。热重分析和 X 射线衍射分析表明，这些反应通过硫酸盐的一种不寻常的机制进行：水通过逐步改变水合数 x 从 La(SO4)·H2O 中去除或插入，而不发生相变。还揭示了只有 La(SO4)的特定结构修饰才能表现出这种可逆的脱水/水合行为。
