Suppressing failure mechanisms in thick Ni-rich cathodes using angstrom-level alumina coatings

Abstract

Enhancing the long-term stability of Ni-rich layered oxide cathodes remains a central barrier to the commercialization of high-energy lithium-ion batteries. Despite progress in surface coating strategies, challenges such as poor uniformity, imprecise thickness control, and limited scalability continue to hinder practical deployment. Herein, we report a scalable, low-temperature atomic layer deposition (ALD) method for conformally coating industrial-scale, thick Ni-rich NMC811 electrodes with ultrathin alumina (Al₂O₃) layers. By precisely controlling the coating thickness via ALD cycles, we identify a 10-cycle coating (∼2 nm) as the optimal condition—achieving a significant improvement in capacity retention without compromising lithium-ion diffusion or rate capability. Comprehensive electrochemical and structural analyses, including in situ XRD, GITT, and DEMS, reveal that the alumina layer effectively suppresses microcracking, inhibits oxygen release, and minimizes transition metal dissolution—the three major degradation pathways in Ni-rich cathodes. Notably, the protective layer also mitigates electrolyte decomposition under high-voltage abuse conditions in commercial 18650-format cells. This work highlights the transformative potential of nanoscale interface engineering through ALD, offering a practical and industrially viable route to durable, safe, and high-performance lithium-ion batteries for next-generation energy storage systems.