The monoclinic (m-LBO) and tetragonal (t-LBO) polymorphs of the lithium metaborate (LiBO₂) material have significant potential for technological applications such as solid electrolytes and electrode coatings of lithium-ion batteries. While comparative studies of electronic, ionic, and photonic properties in these polymorphs exist, the role of lattice vacancies in lithium-ion transport in these polymorphs remains unclear. In this study, we employed density functional theory (DFT) to investigate the formation of lattice vacancies and their impacts on the lattice structure, electronic properties, and the lithium-ion migration energy barrier (E_m) in both m-LBO and t-LBO. Our DFT results reveal that boron and oxygen vacancies affect the lithium-ion transport in both the polymorphs, but in different ways. While oxygen vacancies lower E_m in m-LBO, they increase it in t-LBO. In contrast, boron vacancies significantly reduce E_m in both m-LBO and t-LBO, leading to a remarkably enhanced ionic conductivity in both the polymorphs. This enhancement in the ionic conductivity could be due to favorable alterations in the crystal and electronic structures caused by the presence of boron vacancies. This improvement suggests a potential strategy for improving the ionic conductivity of the LiBO₂ material through boron vacancy generation. For example, boron vacancies might be created in the lattice structures of the LiBO₂ material using controlled neutron irradiation.

中文翻译：

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晶格空位的形成及其对 LiBO2 晶体中锂离子传输的影响：比较 Ab Initio 研究


偏硼酸锂 （LiBO₂） 材料的单斜晶型 （m-LBO） 和四方 （t-LBO） 多晶型物在固体电解质和锂离子电池电极涂层等技术应用方面具有巨大潜力。虽然存在这些多晶型物中电子、离子和光子特性的比较研究，但晶格空位对这些多晶型物中锂离子传输的作用仍不清楚。在这项研究中，我们采用密度泛函理论 （DFT） 来研究晶格空位的形成及其对 m-LBO 和 t-LBO 中晶格结构、电子性质和锂离子迁移能垒 （EM） 的影响。我们的 DFT 结果表明，硼和氧空位在两种多晶型物中影响锂离子传输，但方式不同。虽然氧空位降低了 m-LBO 的 Em，但它们增加了 t-LBO 的 EM。相比之下，硼空位显著降低了 m-LBO 和 t-LBO 中的 E_m，导致两种多晶型物的离子电导率显着增强。离子电导率的这种增强可能是由于硼空位的存在导致晶体和电子结构的有利变化。这一改进提出了一种通过产生硼空位来提高 LiBO₂ 材料离子电导率的潜在策略。例如，使用受控中子辐照，可以在 LiBO₂ 材料的晶格结构中产生硼空位。