LiBH_4中本征缺陷、掺杂剂、掺杂剂-缺陷复合体的第一原理研究(英文)

First-principles study of intrinsic defects,dopants and dopant-defect complexes in LiBH_4

基于密度泛函理论对储氢材料 LiBH4 中氢空位、金属掺杂、金属掺杂-空位复合体进行第一原理研究。研究发现氢空位和金属掺杂都不容易实现,因此它们的浓度都很低。一类缺陷的存在有助于另一类缺陷的形成。基于电子结构的分析,得出 LiBH4中加入金属催化剂导致的释氢动力学性能改善是由于金属催化剂使 B—H键减弱,使新体系更具有金属性,从而使氢扩散更容易;氢空位是 LiBH4分解过程中释放少量 BH3的原因;金属掺杂减弱了 B—H键,致使 LiBH4的释氢温度降低;在掺杂-空位复合体中,金属掺杂剂和空位的作用可以叠加。

A first-principles study was reported based on density functional theory of hydrogen vacancy,metal dopants,metal dopant-vacancy complex in LiBH4,a promising material for hydrogen storage.The formation of H vacancy and metal doping in LiBH4 is difficult,and their concentrations are low.The presence of one kind of defect is helpful to the formation of other kind of defect.Based on the analysis of electronic structure,the improvement of the dehydrogenating kinetics of LiBH4 by metal catalysts is due to the weaker bonding of B—H and the new metal-like system,which makes H atom diffuse easily;H vacancy accounts for a trace amount of BH3 release during the decomposing process of LiBH4;metal dopant weakens the strength of B—H bonds,which reduces the dehydriding temperature of LiBH4.The roles of metal and vacancy in the metal dopant-vacancy complex can be added in LiBH4 system.