金属元素替代对Li4BN3H10储氢材料释氢影响机理的第一性原理研究

应用基于密度泛函理论的赝势平面波第一性原理方法研究了金属元素替代对Li₄BN₃H₁₀ 释氢的影响机理.计算给出了结合能、电子态密度、密集数, 分析了结构的稳定性和原子间的成键情况.结果表明: 晶体的结合能与(LiM)₄BN₃H₁₀(M=Ni,Ti,Al,Mg)释氢性能没有直接的关联.带隙的宽窄和带隙中是否存在杂质能级是决定(LiM)< 关键词： LiBNH系储氢材料 第一性原理 元素替代 释氢机理

First-principles study on influence of alloying element substitution on dehydrogenation ability of Li4 BN3 H10 hydrogen storage materials

A first-principles plane-wave pseudopotential method based on the density functional theory is used to investigate the dehydrogenation properties and the influence mechanism of Li₄BN₃H₁₀ hydrogen storage materials. The binding energy, the density of states and the Mulliken overlap population are calculated. The results show that the binding energy of crystal has no direct correlation with the dehydrogenation ability of (LiM)₄BN₃H₁₀(M=Ni,Ti,Al,Mg). The width of band gap and the energy level of impurity are key factors to affect the dehydrogenation properties of (LiM)₄BN₃H₁₀ hydrogen storage materials: the wider the energy gap is, the more strongly the electron is bound to the bond, the more difficultly the bond breaks, and the higher wile the dehydrogenation temperature be. Alloying introduces the impurity energy level in band gap, which leads the Fermi level to enter into the conduction band and the bond to be weakened, thereby resulting in the improvement of the dehydrogenation properties of Li₄BN₃H₁₀. It is found from the charge population analysis that the bond strengths of N—H and B—H are weakened by alloying, which improves the dehydrogenation properties of Li₄BN₃H₁₀.