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| Home > Publications database > Lithium insertion in hard carbon as observed by $^7$Li NMR and XRD. The local and mesoscopic order and their relevance for lithium storage and diffusion |
| Home > Publications database > Lithium insertion in hard carbon as observed by $^7$Li NMR and XRD. The local and mesoscopic order and their relevance for lithium storage and diffusion |
| Journal Article | PUBDB-2022-04108 |
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2022
RSC
London [u.a.]
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Please use a persistent id in citations: doi:10.1039/D2TA00078D doi:10.3204/PUBDB-2022-04108
Abstract: We investigate hard carbon fibers in different states of charge by a combination of $^7$Li-NMR and 2D-XRD. In particular, we record the quadrupole-split $^7$Li-NMR spectra and $^7$Li longitudinal relaxation over a wide temperature range, and determine lithium self-diffusion both parallel and perpendicular to the fiber axis. Recording the temperature dependence permits us to interpret the presence of motional averaging of spin couplings for mobile Li. The joint analysis shows that at low Li content, Li occupies sites that lack ordered coordination and delocalized electrons and are collected in disordered spatial domains. Upon increasing the Li content, ordered sites collected in ordered domains become populated. Both disordered and ordered domains have a high inherent heterogeneity with a typical spatial extension of a few nanometers. The disordered domains exhibit a continuous topology that permits unhindered diffusion within it. At high Li content we also observe the presence of very small (∼nm) particles of metallic lithium. The joint analysis of XRD in combination with diffusion anisotropy, and anisotropy from the $^7$Li-NMR spectrum (with samples oriented differently with regard to the applied magnetic field), shows that the mesoscopic structure is made by ordered domains arranged in a cylindrically rolled-up manner with the mesoscopic axis parallel to the fiber axis.
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; Allianz-Lizenz / DFG ; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF >= 10 ; JCR ; National-Konsortium ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection
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