Ab initio study of the enhancement of lithium-ion transport in in LiBO₂ crystals in presence of lattice vacancies

Solid-state ionic materials require enhanced ionic conductivity for them to be feasible in solid-state devices such as batteries, fuel cells, and supercapacitors. Here we consider the effect of lattice vacancies in the Li-ion transport; these defects could be produced uniformly through the sample by means of thermal neutron irradiation, e.g., through the boron neutron capture reaction ¹⁰B + ¹n → ⁷Li + ⁴He + 2.79 MeV (see poster session for experimental details [1]). Our density functional theory (DFT) calculations show that B vacancies significantly reduce the activation energy (E_m) of Li-ion transport in both monoclinic and tetragonal polymorphs of LBO₂ leading to a significant enhancement of the ionic conductivity [2]. In contrast, while O vacancies lower E_m in m-LBO, they increase it in t-LBO [2].

References:

1. HM Nguyen, et al., Characterization of Lithium Metaborate (LiBO₂) Irradiated with Thermal Neutrons, to be published in J. Mater. Chem. A.

2. C. Ziemke, et al., Formation of lattice vacancies and their effects on lithium-ion transport in LiBO₂ crystals: comparative ab initio studies, J. Mater. Chem. A 13, 3146 (2025). https://doi.org/10.1039/D4TA05713A.