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How overdischarge destabilizes NCM cathodes : A combined study on structural evolution and chemical states

Xiao, Shu ; Zhu, Jian ; Geng, Xin ; Liu, Zhimeng ; Hou, Xu LU orcid ; Hoffknecht, Jan Philipp ; Świętosławski, Michał ; Li, Hongjiao and He, Xin (2026) In Journal of Energy Storage 142.
Abstract

Overdischarge poses severe challenges to the structural integrity and electrochemical performance of layered LiNixCoyMn1-x-yO2 (NCM) cathodes in lithium-ion batteries, yet the underlying degradation mechanisms remain insufficiently understood. Through a combined experimental and theoretical approach, this study systematically investigates how overdischarge destabilizes NCM cathodes with varying transition metal (TM) ratios (NCM442, NCM523, NCM811). Electrochemical analysis reveals that deep discharge to 0.8 V forces excessive lithiation, generating anomalously high initial capacities (>700 mAh g−1) but causing severe capacity fade in cycling. Characterizations including hard... (More)

Overdischarge poses severe challenges to the structural integrity and electrochemical performance of layered LiNixCoyMn1-x-yO2 (NCM) cathodes in lithium-ion batteries, yet the underlying degradation mechanisms remain insufficiently understood. Through a combined experimental and theoretical approach, this study systematically investigates how overdischarge destabilizes NCM cathodes with varying transition metal (TM) ratios (NCM442, NCM523, NCM811). Electrochemical analysis reveals that deep discharge to 0.8 V forces excessive lithiation, generating anomalously high initial capacities (>700 mAh g−1) but causing severe capacity fade in cycling. Characterizations including hard X-ray absorption spectroscopy (XAS) demonstrates irreversible structural changes which follow a Ni-content-dependent trend (NCM811 > NCM523 > NCM442). Density functional theory (DFT) calculations unveil that the progressive lithiation causes over-reduction of TM oxides and formation of unique Li-O-Li configurations with reactive orphaned oxygen (85 % in Li3TMO3 for NCM811), which impedes structural recovery. The overdischarge voltage plateaus were theoretically predicted and aligns well with experimental findings. These findings provide fundamental insights into overdischarge induced degradation and practical guidelines for optimizing voltage windows of NCM cathodes.

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author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
keywords
Cathode materials, Lithium-ion batteries, NCM materials, Overdischarge, Structural degradation
in
Journal of Energy Storage
volume
142
article number
119585
pages
8 pages
publisher
Elsevier
external identifiers
  • scopus:105022786606
ISSN
2352-1538
DOI
10.1016/j.est.2025.119585
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 Elsevier Ltd
id
710f25f1-cc0a-4468-a023-a5bccec29082
date added to LUP
2025-12-05 22:17:47
date last changed
2025-12-09 13:10:01
@article{710f25f1-cc0a-4468-a023-a5bccec29082,
  abstract     = {{<p>Overdischarge poses severe challenges to the structural integrity and electrochemical performance of layered LiNi<sub>x</sub>Co<sub>y</sub>Mn<sub>1-x-y</sub>O<sub>2</sub> (NCM) cathodes in lithium-ion batteries, yet the underlying degradation mechanisms remain insufficiently understood. Through a combined experimental and theoretical approach, this study systematically investigates how overdischarge destabilizes NCM cathodes with varying transition metal (TM) ratios (NCM442, NCM523, NCM811). Electrochemical analysis reveals that deep discharge to 0.8 V forces excessive lithiation, generating anomalously high initial capacities (&gt;700 mAh g<sup>−1</sup>) but causing severe capacity fade in cycling. Characterizations including hard X-ray absorption spectroscopy (XAS) demonstrates irreversible structural changes which follow a Ni-content-dependent trend (NCM811 &gt; NCM523 &gt; NCM442). Density functional theory (DFT) calculations unveil that the progressive lithiation causes over-reduction of TM oxides and formation of unique Li-O-Li configurations with reactive orphaned oxygen (85 % in Li<sub>3</sub>TMO<sub>3</sub> for NCM811), which impedes structural recovery. The overdischarge voltage plateaus were theoretically predicted and aligns well with experimental findings. These findings provide fundamental insights into overdischarge induced degradation and practical guidelines for optimizing voltage windows of NCM cathodes.</p>}},
  author       = {{Xiao, Shu and Zhu, Jian and Geng, Xin and Liu, Zhimeng and Hou, Xu and Hoffknecht, Jan Philipp and Świętosławski, Michał and Li, Hongjiao and He, Xin}},
  issn         = {{2352-1538}},
  keywords     = {{Cathode materials; Lithium-ion batteries; NCM materials; Overdischarge; Structural degradation}},
  language     = {{eng}},
  month        = {{01}},
  publisher    = {{Elsevier}},
  series       = {{Journal of Energy Storage}},
  title        = {{How overdischarge destabilizes NCM cathodes : A combined study on structural evolution and chemical states}},
  url          = {{http://dx.doi.org/10.1016/j.est.2025.119585}},
  doi          = {{10.1016/j.est.2025.119585}},
  volume       = {{142}},
  year         = {{2026}},
}