DFT+U insights into the structural, surface and hydrogen fluoride adsorptions on Li2MnO3 for Li-ion batteries

• High covergae of HF exhibit a noticeable outwards relaxation with a decrease in adsorption energies. • Observed a blue shift in relation to the isolated molecule, indicating the binding strength between the interacting atoms. • Bader charge analysis displayed a minimal charge transfer with the electronic density of states showing the emergence of Li-F and H-O peaks with no effect on the surface bandgap. The formation of acidic hydrogen fluoride (HF) upon liquid electrolyte decomposition results in Li-Mn-O cathode material degradations and capacity fading during cycling. Even with the extensive research on electrolyte decomposition, degradation mechanisms, and capacity retention improvement strategies, further research is required to comprehend the surface interactions of HF with the layered Li-rich Mn-based Li 2 MnO 3 cathode material. Hence, this work discusses the surface properties and effect of HF adsorption on the major Li 2 MnO 3 surface using the density functional theory (DFT) method. During single HF adsorption, the molecule spontaneously dissociates to form Li-F and H-O species on the surface with an average adsorption energy ( E ads ) of −1.90 eV. However, increasing the HF surface coverage ( θ ) generally resulted in a decrease in E ads , whereas for the full monolayer, we observed a slight drop with reference to the θ = 0.33. It can be noted that the incorporation of HF enhances the stability of the (001) surface, which improves with an increase in surface coverage. The calculated work function increases with an increase in surface coverage, with a slight drop upon full coverage, suggesting a decrease in reactivity compared to the pristine (001) surface. Upon attaining a monolayer, the newly formed Li-F species on the surface greatly relaxed outwards with the highest average charge accumulation of −0.191 e - . The electronic density of states shows no effect of HF surface adsorptions on the bandgap, however, the emergence of Li-F and H-O peaks on the valence band. Our results provide a closer look into the surface properties and HF interactions with the major Li 2 MnO 3 surface for aqueous lithium-ion battery.