Ethylene carbonate adsorption on the major surfaces of lithium manganese oxide LiMnO spinel (0.000 < < 0.375): a DFT+-D3 study

• Published in: Physical chemistry chemical physics : PCCP 2020-03, Vol.22 (12), p.6763-6771
• Main Authors: Ramogayana, Brian, Santos-Carballal, David, Aparicio, Pablo A, Quesne, Matthew G, Maenetja, Khomotso P, Ngoepe, Phuti E, de Leeuw, Nora H
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c9cp05658k

Understanding the surface reactivity of the commercial cathode material LiMn 2 O 4 towards the electrolyte is important to improve the cycling performance of secondary lithium-ion batteries and to prevent manganese dissolution. In this work, we have employed spin-polarized density functional theory calculations with on-site Coulomb interactions and long-range dispersion corrections [DFT+ U -D3-(BJ)] to investigate the adsorption of the electrolyte component ethylene carbonate (EC) onto the (001), (011) and (111) surfaces of the fully lithiated and partially delithiated Li 1− x Mn 2 O 4 spinel (0.000 < x < 0.375). The surface interactions were investigated by evaluating the adsorption energies of the EC molecule and the surface free energies. Furthermore, we analyzed the impact of EC adsorption on the Wulff crystal morphologies, the molecular vibrational frequencies and the adsorbate/surface charge transfers. The adsorption energies indicate that the EC molecule strongly adsorbs on the (111) facet, which is attributed to a bidentate binding configuration. We found that EC adsorption enhances the stability of the (111) facet, as shown by the Wulff crystal morphologies. Although a negligible charge transfer was calculated between the spinel surfaces and the EC molecule, a large charge rearrangement takes place within the surfactant upon adsorption. The wavenumbers of the C&z.dbd;O stretching mode for the interacting EC molecule are red-shifted with respect to the isolated adsorbate, suggesting that this bond becomes weaker. The surface free energies show that both the fully lithiated and partially delithiated forms of the LiMn 2 O 4 surfaces are stabilized by the EC molecule. Surface reactivity of LiMn 2 O 4 spinel cathode material towards ethylene carbonate (EC) electrolyte solvent using density functional theory (DFT).