Journal article

Publication year: 2017

Pages: 3286-3294

Journal: Journal of Physical Chemistry C

Volume number: 121

Issue number: 6

ISSN: 1932-7447

eISSN: 1932-7455

DOI Link: https://doi.org/10.1021/acs.jpcc.6b12885

Publisher: American Chemical Society

Abstract: 
In the near future, the targets for lithium-ion batteries concerning
specific energy and cost can advantageously be met by introducing
layered LiNi_xCo_yMn_zO₂ (NCM) cathode materials with a high Ni content (x
≥ 0.6). Increasing the Ni content allows for the utilization of more
lithium at a given cell voltage, thereby improving the specific capacity
but at the expense of cycle life. Here, the capacity-fading mechanisms
of both typical low-Ni NCM (x = 0.33, NCM111) and high-Ni NCM (x
= 0.8, NCM811) cathodes are investigated and compared from
crystallographic and microstructural viewpoints. In situ X-ray
diffraction reveals that the unit cells undergo different volumetric
changes of around 1.2 and 5.1% for NCM111 and NCM811, respectively, when
cycled between 3.0 and 4.3 V vs Li/Li⁺. Volume changes for NCM811 are largest for x(Li) < 0.5 because of the severe decrease in interlayer lattice parameter c
from 14.467(1) to 14.030(1) Å. In agreement, in situ light microscopy
reveals that delithiation leads to different volume contractions of the
secondary particles of (3.3 ± 2.4) and (7.8 ± 1.5)% for NCM111 and
NCM811, respectively. And postmortem cross-sectional scanning electron
microscopy analysis indicates more significant microcracking in the case
of NCM811. Overall, the results establish that the accelerated aging of
NCM811 is related to the disintegration of secondary particles caused
by intergranular fracture, which is driven by mechanical stress at the
interfaces between the primary crystallites.

Harvard Citation style: Kondrakov, A., Schmidt, A., Xu, J., Geßwein, H., Mönig, R., Hartmann, P., et al. (2017) Anisotropic Lattice Strain and Mechanical Degradation of High- and Low-Nickel NCM Cathode Materials for Li-Ion Batteries, Journal of Physical Chemistry C, 121(6), pp. 3286-3294. https://doi.org/10.1021/acs.jpcc.6b12885

APA Citation style: Kondrakov, A., Schmidt, A., Xu, J., Geßwein, H., Mönig, R., Hartmann, P., Sommer, H., Brezesinski, T., & Janek, J. (2017). Anisotropic Lattice Strain and Mechanical Degradation of High- and Low-Nickel NCM Cathode Materials for Li-Ion Batteries. Journal of Physical Chemistry C. 121(6), 3286-3294. https://doi.org/10.1021/acs.jpcc.6b12885