Probing the Intrinsic Lattice Effects of Low-Concentration Dopants in LiNiO ₂ Cathodes via Atomic-Scale Theoretical Study

Understanding how low-concentration cation doping affects the intrinsic lattice structure and electrochemical properties of a LiNiO2 (LNO) cathode is of significant theoretical and practical value. In this work, we systematically investigate the phase transition behavior of LNO and the effects of various dopants from an atomic-scale perspective. Our calculations reveal that the fully lithiated O3 phase is thermodynamically more stable, while the O1 and O3 phases exhibit comparable stability in the delithiated state. The O3–O1 phase transition is thermodynamically promoted yet kinetically impeded by Li/Ni disorder, indicating its potential as a tuning factor. Based on four key performance metrics, we classify the dopants into three strategic categories. Notably, high-valence dopants (W, Ta/Nb, Mo, and Sb) concurrently optimize volume suppression, TM-O bond reinforcement, and surface stability, making them prime candidates for bulk doping. Most dopants promote an increase in the c-lattice parameter and Li-layer spacing in the lithiated state. Upon delithiation, all systems exhibit an initial lattice expansion followed by contraction, and most dopants help reduce the magnitude of c-axis and volume changes, thereby mitigating detrimental structural strain. Finally, a comprehensive summary is suggested to evaluate the roles of different dopants. This work provides mechanistic insights into the intrinsic effects of doping and offers a theoretical basis for the rational design of robust, high-performance Ni-rich cathodes.