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Multimodal X-ray Probing of the Capacity Fade Mechanisms of Nickel Rich NMC – Progress and Outlook

Published

Author(s)

Cherno Jaye, Daniel A. Fischer, Calvin Quilty, Patrick West, Wenzao Li, Mikaela Dunkin, Garrett Wheeler, Steven Ehrlich, Lu Ma, Esther Takeuchi, Kenneth Takeuchi, David Bock, Amy Marschilok

Abstract

NMC is a commercially successful Li-ion battery cathode due to its high energy density; however, its delivered capacity must be intentionally limited to achieve capacity retention over extended cycling. To design next-generation NMC batteries with longer life and higher capacity the origins of high potential capacity fade must be understood. Operando hard X-ray characterization techniques are critical for this endeavor as they allow the acquisition of information about the evolution of structure, oxidation state, and coordination environment of NMC as the material (de)lithiates in a functional battery. This perspective outlines recent developments in the elucidation of capacity fade mechanisms in NMC through both operando bulk hard X-ray probes as well as surface sensitive soft X-ray characterization. A case study on the effect of charging potential on NMC811 over extended cycling is presented to illustrate the benefits of these approaches. The results showed that charging to 4.7 V leads to higher delivered capacity, but much greater fade as compared to charging to 4.3 V. Operando XRD and SEM results indicated that particle fracture from increased structural distortions at >4.3 V was a contributor to capacity fade. Operando hard XAS revealed significant Ni and Co redox during cycling as well as a Jahn-Teller distortion at the discharged state (Ni3+); however, minimal differences were observed between the cells charged to 4.3 V and 4.7 V. Additional XAS analyses using soft X-rays revealed significant surface reconstruction after cycling to 4.7 V, revealing another contribution to fade. The work demonstrates the utility of hard operando X-ray characterization in studying the causes of capacity fade in NMC and illustrates the special utility of soft XAS to characterize reconstructed surfaces.
Citation
Physical Chemistry Chemical Physics
Volume
24

Keywords

Energy, Li-ion, Batteries, Capacity, NMC, XAS, XRD

Citation

Jaye, C. , Fischer, D. , Quilty, C. , West, P. , Li, W. , Dunkin, M. , Wheeler, G. , Ehrlich, S. , Ma, L. , Takeuchi, E. , Takeuchi, K. , Bock, D. and Marschilok, A. (2022), Multimodal X-ray Probing of the Capacity Fade Mechanisms of Nickel Rich NMC – Progress and Outlook, Physical Chemistry Chemical Physics, [online], https://doi.org/10.1039/d1cp05254c, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933820 (Accessed March 3, 2024)
Created April 22, 2022, Updated December 31, 2022