Atomic Layer Fluorination of the Li4Ti5O12 Surface: A Multiprobing Survey

Li4Ti5O12 (LTO) particles are successfully modified by an atomic layer fluorination process using a one-shot solvent-free synthesis performed with a solid-state fluorinating agent, xenon difluoride, at room temperature. LTO is reported as a promising anode material for lithium-ion batteries (LIBs) where high charging rates and long cycle life are required, because of its high potential preventing lithium dendrite deposition. The fluorination leads to the formation of passivating “LiF” environments at the particle surface using the lowest amount of fluorine reported in the literature. Thanks to a multiprobing strategy, the impact of the fluorination on nonmodified, noncoated LTO has been characterized from the bulk to the extreme surface. The XRD patterns as well as the Raman spectra show no structural modification of the bulk while the combination of the XPS and NMR analysis gives insights about the impact of the fluorination on the entirety of the material. Auger fluorine chemical mapping displays the spatial distribution of a fluorinated layer all around the LTO particles.