化学计量比和放氢背压对LiBH4+xMg2NiH4体系放氢性能的影响

研究了不同化学计量比(x=0.25, 0.5, 0.75, 1.0, 1.25)和放氢背压(1×10-4和0.4 MPa)对LiBH4+xMg2NiH4复合体系吸放氢性能的影响. 结果表明, 随着化学计量比(x)的增加, 复合体系的放氢温度逐渐降低, 放氢动力学性能得到提高, 但放氢容量逐渐降低; 其中, 在1×10-4和0.4 MPa初始放氢背压下, LiBH4+0.75Mg2NiH4体系具有最佳放氢动力学性能和较高的储氢容量. 结果表明, 放氢背压和化学计量比均会对高温下液相LiBH4 与固态Mg2NiH4 的润湿性产生影响, 进而影响复合体系的放氢路径和放氢动力学性能.

Effects of Stoichiometry and Dehydrogenation Back-pressure on the Dehydrogenation Behavior of LiBH4+xMg2NiH4 Composites

The effects of stoichiometry(x=0.25,0.5,0.75,1.0,1.25) and hydrogen back pressure on the dehydrogenation behavior of LiBH4+xMg2NiH4 composites were investigated systematically by methods of X-ray diffraction(XRD) and temperature programmed desorption(TPD) analysis.The results show that the stoichiometry x has a great effect on the dehydriding kinetics of LiBH4+xMg2NiH4 composites.With the increase of x value for the LiBH4+xMg2NiH4 composites,the decrease of the dehydrogenation temperature and the improvement of the dehydriding kinetics are observed but with a loss of dehydrogenation capacity.Thereinto,LiBH4+0.75Mg2NiH4 composite has the best dehydriding kinetics and a relatively high hydrogen storage capacity under initial hydrogen back pressure of 1×10-4 or 0.4 MPa.The analysis shows that both the stoichiometry x of the LiBH4+xMg2NiH4 mixtures and hydrogen back pressure can influence the wetting between liquid LiBH4 and solid Mg2NiH4,and have a great effect on the dehydrogenation path and kinetics furthermore.