Unravelling a layered LiNiO₂ surface, surface doping, and interaction with the electrolyte: computational study

Nickel-rich lithium-ion batteries, such as monoclinic LiNiO₂, have garnered significant attention due to their high specific capacity (275 mAh/g) and energy density (629 Wh/kg), making them attractive for renewable energy applications. Despite these advantages, challenges such as low cycling stability and structural instability limit their practical use. This study employed a first-principles density functional theory (DFT) and METADISE code modelling to investigate the bulk structural properties and low Miller index surfaces of LiNiO₂. The calculated lattice parameters align with experimental data, with a deviation of less than 1.5 %, and the heat of formation (−624.37 kJ/mol) confirms thermodynamic stability. Elastic constants fulfil the monoclinic stability criteria, indicating mechanical stability, although phonon dispersion curves show imaginary modes along the Γ region, signaling structural instability. The effects of Mn and Nb doping on the (101) surface was also examined. Both dopants reduce surface free energies relative to the pristine surface, thereby stabilizing the structure. Furthermore, Nb and Mn doping significantly enhance surface stability and ethylene carbonate (EC) adsorption strength, improving the material's suitability as a cathode in high-performance lithium-ion batteries. • DFT calculations were used to study the fundamental properties of monoclinic LiNiO 2 . • Nb and Mn doping on the (101) surface lowers surface free energy, enhancing surface stability and structural integrity. • Electronic structure analysis shows Nb-doping improves metallicity and conductivity. • Mn-doping maintains partial semiconducting behavior. • Adsorption of ethylene carbonate is stronger on Nb/Mn-doped surfaces, promoting a stable cathode–electrolyte interphase.