Liu Yongfeng, Yang Yaxiong, Zhang Xin, Li You, Gao Mingxia, Pan Hongge
State Key Laboratory of Silicon Materials, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
Dalton Trans. 2015 Nov 7;44(41):18012-8. doi: 10.1039/c5dt03334a. Epub 2015 Sep 28.
The thermal dehydrogenation process of the KOH-containing Mg(NH2)2-2LiH system was systematically investigated by identifying changes in the structure and composition of its components by XRD and FTIR. During ball milling, the added KOH reacts with Mg(NH2)2 and LiH to produce MgO, KH and Li2K(NH2)3. During the initial heating process (<120 °C), the newly formed KH and Li2K(NH2)3 react with Mg(NH2)2 and LiH to yield MgNH, LiNH2 and Li3K(NH2)4 along with hydrogen release. Raising the temperature to 185 °C results in a reaction between Mg(NH2)2, MgNH and LiH that gives Li2Mg2N3H3 as the product and further releases hydrogen. As the temperature is increased to 220 °C, Li2Mg2N3H3 reacts with LiNH2 and LiH to produce Li2MgN2H2 and H2. Meanwhile, two parallel reactions between Li2Mg2N3H3, Li3K(NH2)4 and LiH also generate additional hydrogen. Specifically, the KH and Li2K(NH2)3, formed in situ during ball milling, serve as reactants in the dehydrogenation reaction of the Mg(NH2)2-2LiH system, which is responsible for the significantly improved thermodynamics and kinetics of hydrogen storage.
通过XRD和FTIR确定含KOH的Mg(NH₂)₂ - 2LiH体系各组分的结构和组成变化，系统研究了其热脱氢过程。球磨过程中，添加的KOH与Mg(NH₂)₂和LiH反应生成MgO、KH和Li₂K(NH₂)₃。在初始加热过程（<120 °C）中，新生成的KH和Li₂K(NH₂)₃与Mg(NH₂)₂和LiH反应，生成MgNH、LiNH₂和Li₃K(NH₂)₄并释放氢气。将温度升至185 °C会导致Mg(NH₂)₂、MgNH和LiH之间发生反应，生成Li₂Mg₂N₃H₃作为产物并进一步释放氢气。当温度升至220 °C时，Li₂Mg₂N₃H₃与LiNH₂和LiH反应生成Li₂MgN₂H₂和H₂。同时，Li₂Mg₂N₃H₃、Li₃K(NH₂)₄与LiH之间的两个平行反应也会产生额外的氢气。具体而言，球磨过程中原位形成的KH和Li₂K(NH₂)₃作为Mg(NH₂)₂ - 2LiH体系脱氢反应的反应物，这使得储氢的热力学和动力学得到显著改善。
