Air-Induced Lithium Extraction from the Near-Surface NMC Family Materials

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In recent years, a type of layered oxide, LiNixMnyCozO2, shortly NMCxyz (where x+y+z=1), has become the preferred cathode material for electric vehicle (EV) batteries. Despite some disorder in the crystal structure due to Li+/Ni2+ cation mixing, the composition offers a high specific capacity of up to 200 mAh g-1 at 4.3 V vs. Li/Li+ 1. Despite offering high discharge capacity, Ni-rich NMCs have some disadvantages, such as lattice oxygen release and material degradation during deep discharge. Moreover, nickel-rich NMCs can react with ambient air, forming impurities on the surface, which complicates slurry preparation and further battery performance 2–4. The objective of this study is to comprehensively evaluate the structural, morphological, and electrochemical changes in the NMC family (111, 622, and 811) after being stored in ambient conditions for at least one month. The findings of our study hold immense significance as they focus on the possible challenges that may arise due to ambient-air lithium extraction from NMC materials.However, there is no consensus in the literature on whether lithium on the NMC surface can harm the material's structural and electrochemical properties, reduce performance and safety concerns, or benefit its protective properties, especially for Ni-rich NMC 5–7. An in-depth analysis of the electrode materials helps to understand the lithium extraction pathway and develop treatment protocols for each NMC family member leading to enhanced long-term performance and safety. Here with this presentation, we would like to underline another aspect not being considered in the literature before, regarding morphological evolution upon ambient conditions and its impact on electrochemical performance. The authors would like to acknowledge the Initiative Excellence Research University of University of Warsaw for financially supporting this work. W. Li, E. M. Erickson, and A. Manthiram, Nat Energy, 5, 26–34 (2020).S. E. Renfrew and B. D. McCloskey, J Am Chem Soc, 139, 17853–17860 (2017).L. A. Kaufman and B. D. McCloskey, Chemistry of Materials, 33, 4170–4176 (2021).L. Hartmann, D. Pritzl, H. Beyer, and H. A. Gasteiger, J Electrochem Soc, 168, 070507 (2021).R. Jung et al., J Electrochem Soc, 165, A132–A141 (2018)C. A. Heck et al., Energy Technology, 11, 2200945 (2023)H. Sheng et al., Advanced Materials, 34, 2108947 (2022).