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Elucidating Cathode Degradation Mechanisms in NMC811/Graphite Cells Under Fast Charge Rates Using Operando Synchrotron Characterization

Published

Author(s)

Cherno Jaye, Daniel A. Fischer, Calvin Quilty, Patrick West, Garrett Wheeler, Lisa Housel, Christoph Kern, Killian Tallman, Lu Ma, Steven Ehrlich, Kenneth Takeuchi, David Bock, Amy Marschilok, Esther Takeuchi

Abstract

Li-ion batteries capable of extreme fast charging (XFC) are in demand to facilitate widespread EV adoption. While the impact of fast charge on the negative electrode has been studied, degradation of state-of-the-art LiNi0.8Mn0.1Co0.1O2 (NMC811) under XFC conditions has not been studied in detail. Herein, cathode degradation is probed in NMC811/graphite batteries by analysis of structural and chemical changes for recovered samples previously cycled under XFC conditions and during cycling. NMC surface reconstruction as determined by soft X-ray absorption was not detected for recovered electrodes. However, bulk redox activity from X-ray absorption near edge structure measurements showed more change in the oxidation state of Ni and Co under the 1C charge rate compared to the 4C rate consistent with the electrochemistry. Increased unit cell volume contraction under the 1C rate as determined by operando X-ray diffraction suggests that higher charge rates may provide a protective effect on the cathode by reducing structural distortion due to less delithiation.
Citation
Journal of the Electrochemical Society
Volume
169
Issue
2

Keywords

Energy, Li-ion, Batteries, Capacity fading mechanisms, NMC, Operando XRD, XAS, Ni-rich NMC, Extreme fast charge

Citation

Jaye, C. , Fischer, D. , Quilty, C. , West, P. , Wheeler, G. , Housel, L. , Kern, C. , Tallman, K. , Ma, L. , Ehrlich, S. , Takeuchi, K. , Bock, D. , Marschilok, A. and Takeuchi, E. (2022), Elucidating Cathode Degradation Mechanisms in NMC811/Graphite Cells Under Fast Charge Rates Using Operando Synchrotron Characterization, Journal of the Electrochemical Society, [online], https://doi.org/10.1149/1945-7111/ac51f5, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933984 (Accessed April 14, 2024)
Created February 17, 2022, Updated December 31, 2022