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采用基于密度泛函理论的第一原理方法,计算了LiBH4-X(X=O,F和Cl)体系的晶体与电子结构及解氢性能.生成热和H原子解离能的计算结果表明:O原子掺杂优先占据LiBH4间隙位,F置换氢原子位,而Cl则取代BH4单元;O,F和Cl掺杂的LiBH4体系结构稳定性发生变化,其中O提高体系解氢效果明显,而F和Cl掺杂受H原子区域环境的影响.态密度、Mulliken电子占据数和电子密度的分析结果表明:B—H之间较强的共价键是LiBH4结构稳定、解氢困难的电子结构根源,O,F和Cl对LiBH4解氢能力影响主要是掺杂改变了H的s态与B的sp态的杂化特性、以及BH4单元与Li的成键作用.
The crystal structure, electron structure and hydrogen desorption property of LiBH4-X (X = O, F and Cl) system were calculated by the first principle method based on density functional theory.The calculation results of the heat of formation and the dissociation energy of H atom showed that: O atom preferentially occupies the interstitial site of LiBH4, F replaces the hydrogen atom site, and Cl replaces the BH4 unit. The structural stability of O, F and Cl-doped LiBH4 system changes. O, And Cl doping are affected by the environment of H atom. The results of state density, Mulliken electron occupation number and electron density show that the strong covalent bond between B and H is the structural source of LiBH4, The effect of O, F and Cl on the hydrogen abstraction ability of LiBH4 is mainly due to the hybridization between the S state of H and the Sp state of B, and the bond formation between BH4 and Li.