Mitigating the High-Charge Detrimental Phase Transformation in LiNiO₂ Using Doping Engineering

High Resolution Image Download MS PowerPoint Slide Cobalt-free layered LiNiO 2 has gained increased interest due to the scarcity and high cost of cobalt. However, LiNiO 2 suffers from poor cycling stability, which is mainly due to oxygen loss and structural instability, especially when operating at high voltages. Herein, we present a doping strategy to mitigate the detrimental O3-to-O1 phase transformation in LiNiO 2 from first-principles calculations. Temperature–composition phase diagrams of pristine and doped Li 1– x NiO 2 are obtained using a cluster-expansion and Monte Carlo simulation approach. We investigate the effects of dopant oxidation states, sizes, and concentrations on the dopant distribution in LiNi 1– y M y O 2 ( M = Sb, Ti, Si, Al, and Mg) as well as the phase transitions during delithiation. We find that introducing high-valence dopants with ionic radii similar to that of Ni 3+ into LiNiO 2 stabilizes the O3-phase cathode bulk structure at high charge. Our results provide a general guidance on using doping engineering to realize Ni-rich, Co-free cathodes for lithium-ion batteries.