Structural and electronic properties of bulk Li2O2: first-principles simulations based on numerical atomic orbitals.

Abstract

The development of advanced materials with high specific energy is crucial for enabling sustainable energy storage solutions, particularly in applications such as lithium-air batteries. Lithium peroxide (Li₂O₂) is a key discharge product in non-aqueous lithium-air systems, where its structural and electronic properties significantly influence battery performance. In this work, we investigate the atomic structure, electronic band structure, and Wannier functions of bulk Li₂O₂using density functional theory. The performance of different basis sets of numerical atomic orbitals is compared with respect to converged plane-wave basis results. We analyse the material's ionic characteristics, the formation of molecular orbitals in oxygen dimers, and the band gap discrepancies between various computational approaches. Furthermore, we develop a localized Wannier basis to model electron-vibration interactions and explore their implications for polaron formation. Our findings provide a chemically intuitive framework for understanding electron-lattice coupling and offer a basis for constructing reduced models that accurately describe the dynamics of polarons in Li₂O₂. These insights contribute to the broader goal of improving energy storage technologies and advancing the field of materials design.