Zr-Doping Improves High-Voltage Cycling Stability of Slightly Li-Rich Nickel Oxide Cathodes

Abstract The continuous drive toward high-energy-density lithium-ion batteries for electric vehicles has intensified interest in cobalt-free, Ni-rich layered cathodes. LiNO2 (LNO), as the end member of Ni-rich systems, offers an exceptional theoretical capacity (~275 mAh g-1) and cobalt-free composition, making it a strong candidate for next-generation cathodes. However, its practical application is severely constrained by intrinsic structural instability, oxygen loss, and rapid capacity fading, especially under high-voltage cycling conditions. In this work, we present a zirconium doping strategy to reinforce the structural and interfacial stability of slightly lithium-enriched LNO cathodes. The optimized Zr-doped cathodes exhibits improved electrochemical performance when cycled up to 4.5 V in both half cells and practical pouch-type full cells. Comprehensive characterization results demonstrate that Zr modification effectively mitigates bulk and interfacial instabilities in ultrahigh-Ni cathodes, providing a promising path forward for the practical deployment of high-energy, cobalt-free lithium-ion batteries.