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DOE OSTI · 3384991

Understanding Discharge‐Driven Growth of Cathode Impedance in Ni‐Rich NMC Cathodes

Sahore, Ritu [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000223909570)·Andrews, Hunter B. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000220919415)·Reeves, Kimberly Shawn [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)]·Zachman, Michael J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)] (ORCID:0000000319101357)·Meyer, Harry M. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000349941664)·Krajewski, Kyle J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)]·Bi, Yujing [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)]·Xiao, Jie [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000255205439)·Li, Mengya [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000295814044)·Quarles, Charles Derrick [Elemental Scientific Inc., Omaha, NE (United States)] (ORCID:0000000195910047)·Manard, Benjamin T. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000207400627)
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Abstract

Degradation of LiNi x Mn y Co 1-x-y O 2 (NMC)-based lithium-ion batteries depends strongly on cut-off voltage ranges. In addition to the high upper cut-off voltage, a high depth of discharge (i.e., lower cut-off voltage) significantly worsens cathode impedance growth and capacity fade during long-term cycling. However, there is currently no consensus on the mechanism behind the negative role of a deep discharge. Here, this phenomenon was investigated in graphite||NMC cells with single-crystal cathodes (LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NMC622) or LiNi 0.76 Co 0.14 Mn 0.10 O 2 (NMC76)) using targeted aging protocols (constant high-voltage holds vs. charge–discharge cycling), while monitoring transition-metal (TM) dissolution, cathode-electrolyte interface (CEI) impedance, and NMC surface composition. We demonstrate a correlation between discharge-driven CEI impedance growth and increased TM dissolution. Furthermore, this degradation pathway is more pronounced in lower-Ni NMC622 than in higher-Ni (NMC76) under comparable delithiation states at charge, with both compositions undergoing the H2→H3 phase transition. X-ray photoelectron spectroscopy (XPS) reveals NMC composition-dependent evolution of surface lattice oxygen and restructured surface layer composition between charged and discharged states. These findings add mechanistic depth to the role of discharge as an active driver of interfacial degradation and provide new insights into its composition dependence.

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25 ENERGY STORAGEanalytical chemistrycathodedissolutionmaterials sciencephase transitionsurface layer

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Sahore, Ritu [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000223909570), Andrews, Hunter B. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000220919415), Reeves, Kimberly Shawn [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)], Zachman, Michael J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)] (ORCID:0000000319101357), Meyer, Harry M. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000349941664), Krajewski, Kyle J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)], Bi, Yujing [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)], Xiao, Jie [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000255205439), Li, Mengya [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000295814044), Quarles, Charles Derrick [Elemental Scientific Inc., Omaha, NE (United States)] (ORCID:0000000195910047), Manard, Benjamin T. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000207400627). 2026-06-26. Understanding Discharge‐Driven Growth of Cathode Impedance in Ni‐Rich NMC Cathodes. https://doi.org/10.1002/smll.74326

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Lithium-ion batteries material25 ENERGY STORAGE subjectCATHODE subjectMaterials Science subjectanalytical chemistry subjectdissolution subjectphase transition subject

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