Ground-state search and modification effects of lanthanide substitution in LiNiO2: a first-principles study
LiNiO2 (LNO) is a high-energy-density, cobalt-free cathode candidate, yet its commercial viability is constrained by Li/Ni disordering, layered-structure degradation, and oxygen loss during cycling. Lanthanide (Ln) doping has experimentally improved high-nickel cathode stability, but first-principles studies of LNO+Ln systems suffer from severe convergence failures and multiple metastable states, attributed to strong Coulomb interactions and diverse 4f electronic configurations. This work establishes a ground-state search method using the 4f electron magnetic moment as a feature in cutoff-energy convergence diagrams. By correlating specific Ln 4f magnetic moments with converged energies, the protocol rapidly identifies the true ground state, reducing computational cost. The ground-state crystal and electronic structures of LNO+Ln (La–Gd) were obtained, and Li/Ni disordering formation energies and oxygen vacancy formation energies were calculated. Ln doping generally enhances structural stability, suppresses Li/Ni disordering, and improves oxygen stability. Among the series, LNO+Ce exhibits the most stable structure, the highest Li/Ni disordering formation energy, and the highest oxygen vacancy formation energy, with a c/a ratio approaching that of LiCoO2 (4.99), indicating strong layered ordering. These computational findings align with experimental reports on Ce-doped high-nickel materials. The workflow provides Uf value recommendations for Ln ions in VASP and offers a stable technical route for simulating lanthanide-doped layered materials, significantly reducing computational resource consumption.