EELS probing of lithium based 2-D battery compounds processed by liquid phase exfoliation

Two-dimensional lithiated nanosheets usually show excellent electrochemical performance due to an increase in surface area and shorter diffusion paths. However, processing techniques, such as shear mixing or liquid phase exfoliation could induce phase changes or knock out some of the structural lithium (Li) ions, what in turn might result in poor electrochemical performance. Here different lithiated layered compounds mainly LiCoO2, LiMn2O4, and Li5Ti4O12 were chemically exfoliated and investigated using electron energy loss spectroscopy (EELS) for their Li-K edge. Further analyses were carried out, looking at the oxygen (O) K edge with their respective transition metal core loss peak (Mn, Co and Ti) which revealed changes in the Energy loss near edge structures (ELNES) when compared to the unlithiated compounds. STEM-EELS analyses confirmed uneven distribution of lithium within the lithiated layered materials. In this work, EELS was used for the first time to detect and to probe the chemical environment of the lithium in liquid phase exfoliated material.