Niobium doping enables durable Ni-rich layered cathodes through interfacial and morphological stabilization with data-driven performance validation

The addition of a small amount of niobium oxide during the synthesis of Nb-modified 9-series Ni-rich layered oxides yields multiple beneficial effects. These include suppression of aluminum segregation from the precursor, refinement of primary particle size within dense spherical secondary particles, mitigation of oxygen release during electrochemical cycling, and reduced structural changes associated with the H2–H3 phase transition at voltages up to 4.3 V vs. Li|Li + . The optimized Nb-doped material with 0.5 mol% Nb addition demonstrates excellent rate capability and improved cycling stability, achieving 85.3% capacity retention after 200 cycles at 1C, even for electrodes with a high active-material mass loading of approximately 8.5 mg cm −2 . The role of Nb in structural and electrochemical stabilization is elucidated using operando X-ray diffraction, ex situ soft X-ray absorption spectroscopy, and complementary microscopy studies. In addition, a gated recurrent unit-based approach enables effective prediction of long-term cycling stability. Overall, this strategy demonstrates a viable pathway toward stabilizing high-energy Ni-rich cathodes while accelerating performance assessment for practical lithium-ion battery applications.