Multimodal study of dis-sodiation mechanisms within individual Na3V2(PO4)2F3 cathode crystals using 4D-STEM-ASTAR and STXM-XANES

Folastre, Nicolas; Cherednichenko, Kirill A.; Cadiou, François; Bugnet, Matthieu; Rauch, E.F.; Olchowka, Jacob; Croguennec, Laurence; Masquelier, Christian; Demortière, Arnaud

doi:10.1017/s1431927621011843

Cited by 3 publications

(4 citation statements)

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“…Consistent with observations from the high angle annular dark-field (HAADF) imaging, the agglomerate was identified as a To enhance the comprehension of the results from the STEM-EDX analysis, a comprehensive 4D-STEM investigation was conducted on two selected areas within the particle agglomerate. Crystallographic orientation and phase mapping were derived through the application of ACOM data-processing methods [37,38], coupled with the use of the ePattern suite for data noise reduction [34]. Consistent with observations from the high-angle annular dark-field (HAADF) imaging, the agglomerate was identified as a conglomerate of primary particles.…”

Section: Resultsmentioning

confidence: 95%

“…To enhance the comprehension of the results from the STEM-EDX analysis, a com prehensive 4D-STEM investigation was conducted on two selected areas within the parti cle agglomerate. Crystallographic orientation and phase mapping were derived through the application of ACOM data-processing methods [37,38], coupled with the use of the ePattern suite for data noise reduction [34]. Consistent with observations from the high angle annular dark-field (HAADF) imaging, the agglomerate was identified as a To enhance the comprehension of the results from the STEM-EDX analysis, a comprehensive 4D-STEM investigation was conducted on two selected areas within the particle agglomerate.…”

Section: Resultsmentioning

confidence: 99%

“…TEM methodologies have been extensively employed to conduct in-depth investigations of battery materials at various scales [24][25][26][27]. Notably, the 4D-STEM ACOM technique has been instrumental in achieving precise phase characterization within batteries, both in situ and postmortem.…”

Section: Introductionmentioning

confidence: 99%

“…Despite the versatility of the 4D-STEM ACOM technique, it encounters limitations in liquid cell environments, primarily due to signal-to-noise reduction caused by multi-scattering effects from the liquid electrolyte's thickness. However, these challenges can be mitigated through applications such as ePattern suite software (1.1 version), as demonstrated in the work of Folastre et al [34]. This algorithm employs registration and reconstruction methods to enhance the pattern identification and denoising of diffraction signals.…”

Section: Introductionmentioning

confidence: 99%

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Investigating Cathode Electrolyte Interphase Formation in NMC 811 Primary Particles through Advanced 4D-STEM ACOM Analysis

Gallegos-Moncayo,

Jean,

Folastre

et al. 2024

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This study focuses on NMC 811 (LiNi0.8Mn0.1Co0.1O2), a promising material for high-capacity batteries, and investigates the challenges associated with its use, specifically the formation of the cathode electrolyte interphase (CEI) layer due to chemical reactions. This layer is a consequence of the position of the Lowest Unoccupied Molecular Orbital (LUMO) energy level of NMC 811 that is close to the Highest Occupied Molecular Orbital (HOMO) level of liquid electrolytes, resulting in electrolyte oxidation and cathode surface alterations during charging. A stable CEI layer can mitigate further degradation by reducing the interaction between the reactive cathode material and the electrolyte. Our research analyzed the CEI layer on NMC 811 using advanced techniques, such as 4D-STEM ACOM (automated crystal orientation mapping) and STEM-EDX, focusing on the effects of different charging voltages (4.3 V and 4.5 V). The findings revealed varying degrees of degradation and the formation of a fluorine-rich layer on the secondary particles. Detailed analysis showed that the composition of this layer differed based on the voltage: only LiF at 4.5 V and a combination of lithium fluoride (LiF) and lithium hydroxide (LiOH) at 4.3 V. Despite LiF’s known stability as a CEI protective layer, our observations indicate that it does not effectively prevent degradation in NMC 811. The study concluded that impurities and unwanted chemical reactions leading to suboptimal CEI formation are inevitable. Therefore, future efforts should focus on developing protective strategies for NMC 811, such as the use of specific additives or coatings.

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Section: Resultsmentioning

confidence: 95%