LiBH_4-X（X=O,F和Cl）体系解氢性能的第一原理计算

摘要

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.%Crystal structure,electronic structure and dehydrogenation properties of LiBH4-X（X=O,F,Cl） system have been studied by first-principles calculation based on density functional theory（DFT）.The re-sults of heat of formation and hydrogen removal energy showed that O atom prefers to occupy the interstitial site,F atom replaces for H atom,while Cl atom substitutes the BH4 unit.H atoms from the LiBH4-O system can be easily released compared with LiBH4 doped F and Cl atom.The dehydrogenation properties of LiBH4 doped F and Cl were affected by the H atoms regional environment.After analysising the densities of states（DOS）,Mulliken populations and the charge distribution,it was found that the effect of O,F and Cl on the dehydrogenation properties of LiBH4 may attribute to the changes of the orbital hybridization of H s and B sp and the bond characteristics between BH4 unit and Li atom.