Density Functional Theory Study of Ethylene Carbonate Adsorption on the (0001) Surface of Aluminum Oxide α-Al₂O₃

Abstract

Surface coating is one of the techniques used to improve the electrochemical performance and enhance the resistance against decomposition of cathode materials in lithium-ion batteries. Despite several experimental studies addressing the surface coating of secondary Li-ion batteries using α-Al2O3, the reactivity of the material toward the electrolyte components is not yet fully understood. Here, we have employed calculations based on the density functional theory to investigate the adsorption of the organic solvent ethylene carbonate (EC) on the major α-Al2O3(0001) surface. During adsorption of a single EC molecule, it was found that it prefers to bind parallel to the surface through its carboxyl oxygen. As the surface coverage (θ) was increased up to a monolayer, we observed larger adsorption energies per EC molecule (E ads/N EC) for parallel interactions and a reduction for perpendicular interactions. We also noted that increasing the surface coverage with both parallel and perpendicularly interacting EC molecules led to a decrease of the surface free energies and hence increased stability of the α-Al2O3(0001) surface. Despite the larger E ads/N EC observed when the molecule was placed parallel to the surface, minimal charge transfer was calculated for single EC interactions and at higher surface coverages. The simulated scanning tunneling microscopy images are also presented for a clean corundum α-Al2O3 surface and after adsorption with different coverages of parallel and perpendicularly placed EC molecules.

Influence of sodium hydroxide on phase transformation of gamma alumina to alpha alumina

“…By contrast, α‐Al 2 O 3 , also known as “corundum,” is the thermodynamically and mechanically stable structural polymorph of alumina. As shown in Figure 1B, it has a rhombohedral structure 25–30 . This stable phase evolves through several polymorphic phase transformations of alumina (Equations and ) 31 .…”

“…As shown in Figure 1B, it has a rhombohedral structure. [25][26][27][28][29][30] This stable phase evolves through several polymorphic phase transformations of alumina (Equations 1a and 1b). 31 Such transformations occur in the temperature range 1050-1200 • C, during which the cubic crystal structure of γ-Al 2 O 3 is transformed into the more thermodynamically stable and highly dense rhombohedral structure of α-Al 2 O 3 .…”

Dual modification on hematite to minimize small polaron effects and charge recombination for sustainable solar water splitting

“…Based on this, we hypothesize that a designed dual modification of hematite using earth abundant elements Al 3+ and Zr 4+ as crystal lattice and interface doping agents, respectively, would improve the overall performance of the photoanode for solar water splitting and achieve benchmark photocurrent values. Al 2 O 3 is isostructural to hematite, crystallizing in the corundum structure with lattice parameters a = b = 4.76 Å and c = 12.989 Å, 27 in contrast to hematite with a = b = 5.03 Å and c = 13.74 Å. 28 The more compact structure of Al 2 O 3 is a result of the greater ionic character of the bonds given the smaller ionic radius of Al 3+ .…”

A DFT + U-D3 Study of the Adsorption of Hydrogen Fluoride and Ethylene Carbonate on the Niobium-Doped (001), (011), and (111) Surfaces of Lithium Manganese Oxide

“…Several techniques have been explored to suppress the Mn 2+ ion dissolution and achieve high-capacity retention and improve electrochemical potential. [22][23][24] These strategies include the deposition of surface coating materials, [25][26][27] surface/bulk doping, 28,29 the synthesis of spinel LiMn 2 O 4 with exposed (111) facets, and tuned Mn 3+ concentrations. 30,31 Cation doping 32 in LiMn 2 O 4 has been recommended as one the most effective methods to reduce the number of trivalent manganese (Mn 3+ ) ions that can undergo the disproportionation reaction outlined by Hunter, 15 i.e.…”