The Effect Of Nb Doping On LiNiO2 (101) Surface: DFT+U Study

• M. Hiine Materials Modelling Centre, University of Limpopo, South Africa https://orcid.org/0000-0003-4811-9927
• P.E. Ngoepe Materials Modelling Centre, University of Limpopo, South Africa https://orcid.org/0000-0003-0523-5602
• K.P. Maenetja https://orcid.org/0000-0002-3199-0946

DOI:

https://doi.org/10.7166/36-3-3347

Abstract

Doping nickel-rich layered metal oxides is a key strategy to enhance the structural stability and performance of lithium-ion battery cathodes. Niobium (Nb) has a larger ionic radius, and higher valence can stabilise the NiO₂ lattice and suppress undesired phase transition. This study uses spin-polarised DFT + U-D3(BJ) calculations to investigate the effect of Nb doping on the (101) surface of LiNiO₂, focusing on the first and second layers. Nb doping improves the crystal lattice and reduces volume change. It also lowers surface free energies compared with the undoped surface, indicating enhanced surface stability. Notably, doping in the second layer stabilises the surface more effectively than in the first layer. Bader charge analysis shows a lower charge on Nb in the first layer, while a higher work function in the first layer suggests greater reactivity. Ethylene carbonate (EC) adsorption on Ni sites of both doped and pristine surfaces yields negative adsorption energies, confirming thermodynamic stability. Among all sites, Ni₂₃ shows the most negative adsorption energy, suggesting the strongest interaction with EC. This study reveals layer-dependent effects of Nb doping and their impact on EC adsorption, providing guidance for designing more stable and efficient LiNiO₂ cathodes.