Chen Yun, Sun Xin, Zhang Wenkui, Gan Yongping, Xia Yang, Zhang Jun, Huang Hui, Liang Chu, Pan Hongge
College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China.
School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
ACS Appl Mater Interfaces. 2020 Apr 1;12(13):15255-15261. doi: 10.1021/acsami.0c00956. Epub 2020 Mar 19.
The Mg(NH)-2LiH system with KOH additive is a promising high-capacity hydrogen storage material in terms of low dehydrogenation temperatures, good reversibility, and excellent cycling stability. Various mechanisms have been reported to elucidate the reasons for the K-containing additive improving the hydrogen storage performance. Herein, the dehydrogenation performance of Mg(NH)-2LiH-0.07KOH is found to be strongly associated with hydrogen pressures. The LiK(NH) and KH produced from the reaction between KOH, LiH, and Mg(NH) in the ball milling process are converted into LiK(NH), MgNH, and LiNH in the heating dehydrogenation process under Ar carrier gas or very low hydrogen pressure, exhibiting a two-peak dehydrogenation process. For the sample under high hydrogen pressure, LiK(NH) can react with LiH to convert into LiK(NH) and further to form KH and LiNH in the heating process, showing a one-peak dehydrogenation process under 5 bar hydrogen. The hydrogen pressure-dependent reactions of K-containing additives in the Mg(NH)-2LiH system lead to a different hydrogen storage performance under different dehydrogenation conditions.
具有KOH添加剂的Mg(NH)-2LiH体系，就其较低的脱氢温度、良好的可逆性和出色的循环稳定性而言，是一种很有前景的高容量储氢材料。已经报道了各种机制来阐明含钾添加剂改善储氢性能的原因。在此，发现Mg(NH)-2LiH-0.07KOH的脱氢性能与氢气压力密切相关。在球磨过程中由KOH、LiH和Mg(NH)反应生成的LiK(NH)和KH，在Ar载气或极低氢气压力下的加热脱氢过程中转化为LiK(NH)、MgNH和LiNH，呈现出双峰脱氢过程。对于在高氢气压力下的样品，LiK(NH)在加热过程中可与LiH反应转化为LiK(NH)，并进一步形成KH和LiNH，在5 bar氢气下呈现单峰脱氢过程。Mg(NH)-2LiH体系中含钾添加剂的氢气压力依赖性反应导致在不同脱氢条件下具有不同的储氢性能。
