Operando mapping of Li concentration profiles and phase transformations in graphite electodes by MRI and NMR

Sergey A. Krachkovskiy, Jamie Foster, Jonathan David Bazak, Bruce J. Balcom, Gillian R. Goward

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Abstract

An innovative combined MRI and NMR methodology, which enables the visualization and spatially resolved quantification of the lithiation/delithiation process in porous Li-ion battery electrodes, in real time, is reported. We demonstrate that polarization of the thick graphite electrode correlates with the appearance of energy barriers during the graphite phase transformations and the resulting significant reduction of the lithium chemical diffusion, which must be addressed in any attempt at the fast charging of Li-ion batteries. It is also shown that a portion of the transported Li + is temporarily stored in the electrode surface film prior to its intercalation into graphite, indicating reversible lithium storage within the surface electrolyte interface. The inclusion of a short current reversal which could be considered as part of a shaped charging process, facilitates the complete lithiation of thick graphite electrodes; an attractive strategy for increasing usable cell capacities.
Original languageEnglish
JournalJournal of Physical Chemistry C
Early online date24 Aug 2018
DOIs
Publication statusEarly online - 24 Aug 2018

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