Neutron-Induced Defects and their Effects on Structural and Electrical Properties of LiBO₂ Material

LiBO₂ material has drawn research interest due to its potential applications such as electrode coatings and solid electrolytes of Li-ion batteries. However, its ionic conductivity is low (~10^-6 – 10^-5 S/cm), requiring improvement. Here, we investigate experimentally the effects of thermal-neutron irradiation on the properties of the monoclinic structure (α phase) of polycrystalline LiBO₂ pellets. Analysis of scanning electron microscopy and x-ray photoelectron spectroscopy show systematic dose-dependent changes of surface microstructure and chemistry, indicating the presence of neutron-induced defects, such as B vacancies, generated due to nuclear reactions between neutrons and ¹⁰B isotopes (~20% of B). In contrast, x-ray diffraction shows no new crystalline phase detectable in irradiated pellets, suggesting that neutron irradiation does not significantly degrade the crystal structure. Electrochemical impedance spectroscopy shows a ~30% increase of the ionic conductivity of pellets irradiated for 60 minutes, suggesting that thermal neutron irradiation might be a viable strategy to improve the ionic conductivity of the LiBO₂ material as first suggested from density functional theory calculations.[1,2]