Cl对LiAlH4解氢性能影响的第一性原理研究

采用基于密度泛函理论的第一性原理方法,计算了LiAlH4-Cl体系的晶体与电子结构及稳定性能。计算生成焓发现,Cl-均可替代LiAlH4晶体结构中不同位置的H原子、AlH4]单元体及占间隙位,其占位难易程度从易到难依次为:间隙位H2位H4位H3位H1位AlH4]单元体。H原子解离能的计算发现:在Cl-替代AlH4]单元和占据间隙位时,LiAlH4体系的结构稳定性变差,对应体系的放氢能力提高。其中,Cl-占据间隙位时,其对应体系放氢能力最强。费米能级附近能隙ΔEH-L值变小,对应体系的结构稳定性降低,是提高LiAlH4体系放氢能力的根本原因。

First-principles Study of Dehydrogenation Properties of LiAlH4 Doped by Cl

Based on the first-principles density functional theory,the crystal of LiAlH4-Cl system and electro-nic structure and stable performance were calculated.It is found that Cl atom can replace H atoms in different posi-tions,AlH4 ]and vacancy of the LiAlH4 crystal structure.The site preference of the ternary additions in LiAlH4 al-loy from easy to difficult is vacancy bits> H2 bits > H4 bits > H3 bits > H1 bits > AlH4 ]bits.The dissociation energy of H atom show that:when Cl atom substituted AlH4 ]and occupied vacancy,there were some changes on structural stability,and befit to improve the dehydrogenating properties of the system.The system had strongest hy-drogen release ability when Cl atoms occupied interstitial sites.Improve LiAlH4 system put the root cause of the hy-drogen capacity:Near the Fermi level energyΔEH-L gap value decreased,the structure stability of the corresponding system reduced.