The role of native defects in the transport of charge and mass and the decomposition of Li$_{4}$BN$_{3}$H$_{10}$

TL;DR

This study uses first-principles calculations to explore native defects in Li4BN3H10, revealing mechanisms for its decomposition and ionic conduction, which are crucial for hydrogen storage and battery applications.

Contribution

It provides a detailed atomistic defect mechanism for decomposition and ion transport in Li4BN3H10, highlighting defect roles in NH3 release and ionic mobility.

Findings

Hydrogen vacancies facilitate NH3 release during decomposition.

Li vacancies and interstitials are highly mobile, aiding ionic conduction.

Native defects significantly influence the material's stability and transport properties.

Abstract

Li$_{4}$BN$_{3}$H$_{10}$ 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 (NH$_{3}$) during the decomposition. We report a first-principles density-functional theory study of native point defects and defect complexes in Li$_{4}$BN$_{3}$H$_{10}$, 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 NH$_{3}$ 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 Li$_{4}$BN$_{3}$H$_{10}$ 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.