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@ARTICLE{Luether:1025077,
author = {Luether, Marco J. and Gomez-Martin, Aurora and Jiang,
Shi-Kai and Schmuch, Richard and Placke, Tobias and Hwang,
Bing-Joe and Winter, Martin},
title = {{I}s the ‘{S}ingle-{C}rystal’ {A}pproach {T}ruly
{F}easible for {N}i-{R}ich {L}ayered {O}xides? – a {F}air
and {R}ealistic {P}erformance {C}omparison in
{N}cm||{G}raphite {C}oin {C}ells},
journal = {Meeting abstracts},
volume = {MA2023-01},
number = {2},
issn = {1091-8213},
address = {Pennington, NJ},
publisher = {Soc.},
reportid = {FZJ-2024-02665},
pages = {487 - 487},
year = {2023},
note = {Hierbei handelt es sich lediglich um einen Abstract.},
abstract = {Secondary particle cracking induced by anisotropic volume
change during cycling has been identified as a major failure
mechanism of state-of-the-art Ni-rich layered oxide cathodes
like Li[NixCoyMnz]O2 (x + y + z = 1, NCMxyz where x ≥ 0.8)
as it allows surface-related degradation phenomena such as
inactive phase formation, transition metal dissolution and
ongoing electrolyte decomposition to continue on newly
formed, highly reactive surface cycle after cycle.1 The
approach of designing 'single-crystal' (SC) particles is
believed to mitigate this issue by replacing polycrystalline
secondary agglomerates (PC) by well-separated micron-sized
primary particles that can prolong the cycle life of the
material by improving its morphological integrity.2Particle
cracking in layered oxide cathode materials is exacerbated
with increasing Ni-content which qualifies the
'single-crystal' approach especially for Ni-rich NCMs (x ≥
0.8). Despite this, meaningful long-term cycling studies are
still scarce as two main challenges obstruct a fair
evaluation of the 'single-crystal' approach: The synthesis
of Ni-rich SC-NCMs is not straightforward as the conditions
required for enhanced crystal growth (e. higher calcination
temperature and/or a molten-salt environment requiring a
washing step) are inherently damaging to Ni-rich materials.3
This often leads to comparisons between materials where
factors other than morphology cannot be excluded (e.g.
synthesis from different precursors, different
post-processing steps, undisclosed dopants/coatings in
commercial materials, etc.). The larger crystal size of
SC-NCMs compared to PC-NCMs is believed to cause kinetic
limitations impacting achievable capacities and rate
performance.4 As a consequence, either the 'single-crystal'
sample is cycled in a lower state-of-charge window despite
the same same upper cut-off voltage or the polycrystalline
reference sample is cycled at an unnecessarily high voltage.
Both conditions favor the 'single-crystal' material.The
objective of this work was to establish a fair comparison
between the two morphologies. For this purpose, a series of
'single-crystal' Li[Ni0.8Co0.1Mn0.1]O2 (SC-NCM811) materials
with varying particle sizes where synthesized. To
deconvolute the effect of particle size and morphology from
other influences, a molten salt-assisted synthesis was
followed, so that bulk properties of SC-NCMs remained
constant and PC-NCM reference samples could be synthesized
from the same home-made precursors and with the same
post-processing steps. The samples were thoroughly
characterized in terms of physicochemical properties and
their electrochemical performance was evaluated in NCM||Li
and NCM||Graphite coin cells. The performance of PC- and
SC-NCM811 was compared at the same upper cutoff voltage and
again at the same state-of-charge window to compare the
materials as fairly as possible.References:(1) de Biasi, L.;
Schwarz, B.; Brezesinski, T.; Hartmann, P.; Janek, J.;
Ehrenberg, H. Chemical, Structural, and Electronic Aspects
of Formation and Degradation Behavior on Different Length
Scales of Ni-Rich NCM and Li-Rich HE-NCM Cathode Materials
in Li-Ion Batteries. Advanced Materials2019, 31 (26).
https://doi.org/10.1002/adma.201900985.(2) Zhao, W.; Zou,
L.; Zhang, L.; Fan, X.; Zhang, H.; Pagani, F.; Brack, E.;
Seidl, L.; Ou, X.; Egorov, K.; Guo, X.; Hu, G.; Trabesinger,
S.; Wang, C.; Battaglia, C. Assessing Long‐Term Cycling
Stability of Single‐Crystal Versus Polycrystalline
Nickel‐Rich NCM in Pouch Cells with 6 MAh Cm −2
Electrodes. Small2022, 2107357, 2107357.
https://doi.org/10.1002/smll.202107357.(3) Langdon, J.;
Manthiram, A. A Perspective on Single-Crystal Layered Oxide
Cathodes for Lithium-Ion Batteries. Energy Storage
Mater2021, 37, 143–160.
https://doi.org/10.1016/j.ensm.2021.02.003.(4) Ryu, H. H.;
Namkoong, B.; Kim, J. H.; Belharouak, I.; Yoon, C. S.; Sun,
Y. K. Capacity Fading Mechanisms in Ni-Rich Single-Crystal
NCM Cathodes. ACS Energy Lett2021, 6 (8), 2726–2734.
https://doi.org/10.1021/acsenergylett.1c01089.},
cin = {IEK-12},
ddc = {540},
cid = {I:(DE-Juel1)IEK-12-20141217},
pnm = {1221 - Fundamentals and Materials (POF4-122)},
pid = {G:(DE-HGF)POF4-1221},
typ = {PUB:(DE-HGF)16},
doi = {10.1149/MA2023-012487mtgabs},
url = {https://juser.fz-juelich.de/record/1025077},
}