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Stable cycling of nickel-rich cathode at high voltage

Electrolyte additive enables the stable cycling of nickel-rich cathodes at ultra-high voltage. Synchrotron studies identify surface-to-bulk interactions as a key factor contributing to the success. X-ray nanotomography coupled with machine learning analysis reveals morphological and chemical information for thousands of particles, providing guidance on how to best leverage such interactions.

Nickel-rich layered battery cell cathode materials, such as lithium nickel manganese cobalt (NMC) oxides, deliver more capacity, and hence more energy, when charged to a high voltage. However, high voltage cycling brings a series of issues including transition metal dissolution, cathode surface reconstruction, crack formation and electrolyte decomposition [1]. These issues destroy the integrity of the cathode at the surface and in the bulk, preventing the stable cycling of battery cells at high voltage.

These problems were solved through an electrolyte engineering approach. An appropriate amount of additive LiPO2F2 (LiDFP) enabled stable cycling of high-Ni layered cathode at an ultra-high voltage of 4.8 V. It was found that the additive forms an interphase that protects the surface of the cathode. Interestingly, the protected

surface facilitates uniform lithium distribution within the bulk particles and mitigates the notorious crack problem facing this type of cathode material.

To quantitatively understand this surface-to-bulk interaction, phase-contrast nanotomography studies were carried out at the nano-imaging beamline ID16A. Thanks to its high-spatial resolution and large field of view, data from thousands of cathode particles could be collected simultaneously. The data were further processed by machine-learning-assisted statistical analysis [2], providing quantitative information on the impact of LiDFP on the bulk heterogeneity at the electrode scale with nanoscale resolution. Building upon accurate particle identification capabilities (Figure 70a), the characteristics of every single NMC particle was quantified in its size, sphericity, state of charge (SOC), SOC variation and anisotropic polarisation.

To elucidate the effect of particle size and shape dependence in their respective responses to the LiDFP- modulated surface chemistry, the identified particles were divided into four groups (small and large volume, low and high sphericity, Figure 70b). The relative values of SOC variation and anisotropic polarisation for these four groups were compared to evaluate the impact of LiDFP (Figure 70c). As indicated by the red arrows (pointing to lower left) in Figure 70c, both the SOC variation and anisotropic polarisation decrease with the presence of

PRINCIPAL PUBLICATION AND AUTHORS

X-ray multiscale 3D neuroimaging to quantify cellular aging and neurodegeneration postmortem in a model of Alzheimer s disease, G.E. Barbone (a,b), A. Bravin (c,d), A. Mittone (c,e), A. Pacureanu (c), G. Mascio (f), P. Di Pietro (f,g), M.J. Kraiger (h), M. Eckermann (a,i), M. Romano (a), M. Hrabě de Angelis (h,j,k), P. Cloetens (c), V. Bruno (f,l), G. Battaglia (f,l), P. Coan (a,b), Eur. J. Nucl. Med. Mol. Imaging 49, 4338-4357 (2022); https:/doi.org/10.1007/s00259-022-05896-5 (a) Maximilians-Universität München, Garching (Germany) (b) Department of Clinical Radiology, Ludwig-Maximilians-Universität München, Munich (Germany) (c) ESRF (d) Present address: Department of Physics, University Milano Bicocca, Milan (Italy) (e) Present address: CELLS-ALBA Synchrotron, Cerdanyola del Valles (Spain) (f) Department of Molecular Pathology, Neuropharmacology Section, I.R.C.C.S. Neuromed, Pozzilli (Italy) (g) Department of Medicine, Surgery and Dentistry, Schola Medica Salernitana, University of Salerno, Baronissi (Italy) (h) Institute of Experimental Genetics and German Mouse Clinic, German Research Center for Environmental Health, Neuherberg (Germany) (i) Institut Für Röntgenphysik, Georg-August-Universität Göttingen, Göttingen (Germany) (j) Department of Experimental Genetics, School of Life Science Weihenstephan, Technical University of Munich, Freising (Germany) (k) German Center for Diabetes Research, Neuherberg (Germany) (l) Department of Physiology and Pharmacology, University Sapienza, Rome (Italy)

REFERENCES

[1] M. Romano et al., Cancers 13, 4953 (2021). [2] A. Horng et al., J. Biomed. Sci. 28, 42 (2021). [3] G.E. Barbone et al., Radiology 298, 135-146 (2021). [4] G.E. Barbone et al., J. Neurosci. Methods 339, 108744 (2020). [5] G.E. Barbone et al., Int. J. Radiat. Oncol. Biol. Phys. 101, 965- 984 (2018). [6] A. Mittone et al., J. Synchrotron Radiat. 27, 1347-1357 (2020). [7] A.T. Kuan et al., Nat. Neurosci. 23, 1637-1643 (2020).

without staining or dissection represents a new technical feat in neuroimaging. This methodology could be exploited by the neuroscience community to observe novel or

overlooked mechanisms of neurodegeneration and could be beneficial to test and evaluate novel neuroprotective strategies for AD and other brain pathologies.