83HIGHLIGHTS 2020

Impact of dual-layer solid-electrolyte interphase inhomogeneities on early-stage defect formation in Si electrodes, C. Chen (a,b), T. Zhou (c,d), D.L. Danilov (a,b), L. Gao (b), S. Benning (a,e), N. Schön (a,e), S. Tardif (f), H. Simons (g), F. Hausen (a,e), T.U. Schülli (c), R.-A, Eichel (a,e) and P.H. Notten (a,b,h), Nat. Commun. 11, 3283

(2020); https://doi.org/10.1038/s41467- 020-17104-9. (a) IEK-9, Forschungszentrum Jülich, Jülich (Germany) (b) Eindhoven University of Technology (The Netherlands) (c) ESRF (d) Nanoscience and Technology Division,

Argonne National Laboratory (USA) (e) RWTH Aachen University (Germany) (f) Univ. Grenoble Alpes, CEA, IRIG-MEM, Grenoble (France) (g) Technical University of Denmark, Kongens Lyngby (Denmark) (h) University of Technology Sydney (Australia)

LINKING SIZE SCALES WITH X-RAY SCATTERING UNCOVERS A NEW MINERAL FRACTION IN HUMAN BONE

The structure of bone remains enigmatic. With a novel technique, a fraction of mineral particles with a difference from the expected alignment between their crystallographic structure and the bone nanostructure was revealed. This prompts further investigations into bone nanostructure. The method is applicable to a wide range of textured materials.

PRINCIPAL PUBLICATION AND AUTHORS

Fig. 66: The Young s modulus, topography, electrochemical strain microscopy amplitude maps and Li 1s X-ray photoelectron spectroscopy spectra of the outer-SEI (top row) and the inner-SEI (bottom row).

defect formation. The SEI layer formed on the single-crystal Si electrode was identified as a complex dual-layer structure consisting of a mostly inorganic (hard) inner-SEI layer and a more organic (soft) outer-SEI layer. Both the inner- and outer-SEI exhibited high degree of inhomogeneities in terms of topography (longer ionic-transportation time for thicker regions), lithium-ion mobility (less conducting for lower mobility) and chemical composition.

These inhomogeneities in SEI inevitably led to a heterogeneous degree of lithiation in the underlying Si electrode, which in turn resulted in mechanical deformations upon cycling. This multi-modal study bridges observations in the depth direction across the multi-level interfaces (Si/LixSi/inner-SEI/outer-SEI), thus offering novel insights into the impact of SEI homogeneities on the structural stability of Si-based lithium-ion batteries.

Our aging society presents increasing problems of poor bone health due to changes in bone structure resulting in impaired mechanical properties, yet an understanding of bone mechanics relies on understanding its

architecture. Bone is mostly made up of collagen fibres and nanocrystalline hydroxyapatite (HA) mineral particles. The outstanding mechanical properties of bone result from the intricate organisation of these components. The central