Altering Hydrogen Storage Properties by Hydride Destabilization through Alloy Formation: LiH and MgH2 Destabilized with Si
Altering Hydrogen Storage Properties by Hydride Destabilization through Alloy Formation: LiH and MgH2 Destabilized with Si
复制标题
DOI：
10.1021/jp040060h
复制
发表时间：
2004-08
影响因子：
3.3
通讯作者：
J. Vajo;F. Mertens;C. Ahn;R. Bowman;B. Fultz
中科院分区：
文献类型：
--
作者：
J. Vajo;F. Mertens;C. Ahn;R. Bowman;B. Fultz
与Si合金化被证明是不稳定的强烈绑定的LiH和MgH2。对于LiH/Si系统，在脱氢时形成Li2.35Si合金，导致490 ° C下的平衡氢压力从约5 × 10 - 5增加到1 bar。对于MgH2/Si系统，Mg2Si在脱氢时形成，导致在300 ° C下的平衡压力从1.8巴增加到> 7.5巴。热力学计算表明，在约20 ° C下平衡压力为1巴，在约150 ° C下为100巴。这些条件表明，具有5.0重量%的氢容量的MgH2/Si系统可以用于在降低的温度下的储氢。LiH/Si系统是可逆的，并且可以循环而不降解。在400 - 500 ° C下获得的吸收/解吸等温线显示出两个明显的平坦平台，几乎没有滞后。平台对应于各种Li硅化物的形成和分解。MgH2/Si系统不容易可逆。Mg2Si的氢化出现了...
Alloying with Si is shown to destabilize the strongly bound hydrides LiH and MgH2. For the LiH/Si system, a Li2.35Si alloy forms upon dehydrogenation, causing the equilibrium hydrogen pressure at 490 °C to increase from approximately 5 × 10-5 to 1 bar. For the MgH2/Si system, Mg2Si forms upon dehydrogenation, causing the equilibrium pressure at 300 °C to increase from 1.8 to >7.5 bar. Thermodynamic calculations indicate equilibrium pressures of 1 bar at approximately 20 °C and 100 bar at approximately 150 °C. These conditions indicate that the MgH2/Si system, which has a hydrogen capacity of 5.0 wt %, could be practical for hydrogen storage at reduced temperatures. The LiH/Si system is reversible and can be cycled without degradation. Absorption/desorption isotherms, obtained at 400−500 °C, exhibited two distinct flat plateaus with little hysteresis. The plateaus correspond to formation and decomposition of various Li silicides. The MgH2/Si system was not readily reversible. Hydrogenation of Mg2Si appears...