Hoang Khang, Janotti Anderson, Van de Walle Chris G
Center for Computationally Assisted Science and Technology, North Dakota State University, Fargo, ND 58108, USA.
Phys Chem Chem Phys. 2014 Dec 14;16(46):25314-20. doi: 10.1039/c4cp03677h. Epub 2014 Oct 22.
Li4BN3H10 is of great interest for hydrogen storage and for lithium-ion battery solid electrolytes because of its high hydrogen content and high lithium-ion conductivity, respectively. The practical hydrogen storage application of this complex hydride is, however, limited due to irreversibility and cogeneration of ammonia (NH3) during the decomposition. We report a first-principles density-functional theory study of native point defects and defect complexes in Li4BN3H10, and propose an atomistic mechanism for the material's decomposition that involves mass transport mediated by native defects. In light of this specific mechanism, we argue that the release of NH3 is associated with the formation and migration of negatively charged hydrogen vacancies inside the material, and it can be manipulated by the incorporation of suitable electrically active impurities. We also find that Li4BN3H10 is prone to Frenkel disorder on the Li sublattice; lithium vacancies and interstitials are highly mobile and play an important role in mass transport and ionic conduction.
Li4BN3H10因其高氢含量和高锂离子传导率，分别在储氢和锂离子电池固体电解质方面具有重大研究价值。然而，由于该复合氢化物在分解过程中存在不可逆性且会产生副产物氨（NH3），其实际储氢应用受到限制。我们报道了对Li4BN3H10中本征点缺陷和缺陷复合体的第一性原理密度泛函理论研究，并提出了该材料分解的原子机制，其中涉及由本征缺陷介导的质量输运。基于这一特定机制，我们认为NH3的释放与材料内部带负电的氢空位的形成和迁移有关，并且可以通过引入合适的电活性杂质来加以控制。我们还发现Li4BN3H10在锂亚晶格上容易出现弗伦克尔无序；锂空位和间隙锂具有高度的迁移性，在质量输运和离子传导中起着重要作用。
