First-principles study on the role of Ti, V, and Sc catalysts in enhancing the catalytic effects of boron oxide monolayer for efficient Lithium-selenium batteries

Abstract

Ongoing research on lithium‑selenium batteries (LiSeB) aims to overcome setbacks caused by shuttle effects by exploring various cathode additive materials, with a particular focus on 2D materials. These materials are gaining popularity because of their unique properties, such as large surface areas, ballistic electronic transport, mechanical strength, and anisotropy, making them promising candidates for cathode additives in LiSeB. In this study, density functional theory (DFT) was used to investigate the interaction of lithium polyselenides (specifically Li₂Se_x where x = 1, 2, 4, 6, and 8, as well as Se₈) on recently synthesized boron monoxide monolayer (BO). We investigated the influence of Li₂Se_x and Se₈ on BO, focusing on the adsorption energy, the charge density distribution, Gibbs free energy changes, and the metallic characteristics for efficient LiSeB. The results showed that the adsorption energies of these Li₂Se_x and Se₈ on pristine BO are relatively weak, ranging from −0.25 to −1.43 eV. In contrast, doping BO with scandium (Sc) significantly increased the adsorption energies, ranging from −2.65 to −3.74 eV, indicating a notable enhancement compared to other single-atom catalysts (SACs). The strong adsorption energy of Sc-doped BO suggested an improved ability to prevent the dissociation of Li₂Se_x and Se₈ in the electrolyte, which is critical to address the notorious shuttle effects. Charge density distribution analyses further supported the presence of electronic interactions between the substrate and the adsorbed Li₂Se_x and Se₈ via Sc catalysts, as evidenced by charge transfer from the adsorbate to the substrate. Furthermore, the investigation of Gibbs free energies revealed low charge, discharge, and overpotential values (0.1 V for pristine BO and 1.53 V for Sc-doped BO). The Sc-doped BO structure exhibited significantly enhanced metallic characteristics after adsorption of Li₂Se and Li₂Se₄. Furthermore, the low diffusion (1.56 eV) and dissociation (1.72 eV) energy barriers for stable Li₂Se on Sc-doped BO suggested the material's potential to improve electrochemical processes and enable higher charging rates in LiSeB. Ultimately, while pristine BO alone may not effectively address the challenges associated with LiSeB, doping it with Sc substantially enhances its properties as a cathode additive.