Spinel nanodomains relieve strain and stabilize lattice oxygen in ultrahigh-nickel zero-cobalt cathodes

Ultrahigh-nickel, zero-cobalt layered oxides are emerging as promising cathodes for next-generation lithium-ion batteries combining high capacity and cost effectiveness. However, the high nickel content and absence of cobalt intensify anisotropic lattice strain and lattice oxygen instability during (de)lithiation, accelerating performance degradation. Contrary to the prevailing view that Li + /Ni 2+ cation mixing is detrimental, we propose that Nb-induced Li + /Ni 2+ mixing enables the spontaneous formation of spinel nanodomains within the layered matrix, which effectively relieve lattice strain and stabilize lattice oxygen during deep delithiation. The optimized cathode exhibits impressive cycling stability, retaining 93.4% of its initial capacity, while reducing voltage decay by 83% compared to the unmodified counterpart (from 1.43 to 0.24 mV per cycle) over 250 cycles. These findings establish a disorder-engineering paradigm by elucidating the formation mechanism and functional role of intergrowth nanodomains within ordered layered frameworks, paving the way toward next-generation stable cathodes with high energy density and cost competitiveness.