Engineering of entropy-driven surface doping towards stabilized high-voltage NCM cathodes : Li (Ni, Co, Mn, Ce, La, Zr, Al) Oₓ

Abstract

Ni-rich LiNi0.8Mn0.1Co0.1O2 (NCM) cathodes in layered oxide cathodes are attractive for high-energy lithium-ion batteries but suffer from rapid capacity fade and thermal instability at high charge voltages. In this study, we propose an entropy-assisted multi-element doping strategy to mitigate these issues. Specifically, two routes are designed and compared: bulk-like localized high-entropy doping (BHE-NCM) and surface-distributed high-entropy-zone doping (SHE-NCM). The surface entropy-doped NCM cathode delivers enhanced electrochemical performance, including higher capacity retention under 4.5 V cycling and superior rate capability, compared to both bulk-like and pristine counterparts. Comprehensive material characterization reveals that surface-localized doping stabilizes the layered structure with reduced microcrack formation and creates a uniform dopant-rich surface region with improved thermal and electrochemical stability. Overall, entropy-assisted doping at the near surface zone effectively alleviates structural degradation and interface reactions in Ni-rich NCM, enabling improved cycling performance at high voltage. This work highlights the significance of surface entropy engineering as a promising strategy for designing high-voltage cathodes with improved safety and longevity. Graphical abstract: [Figure not available: see fulltext.]