EELS PROBING OF LITHIUM BASED 2-D BATTERY COMPOUNDS PROCESSED BY LIQUID PHASE EXFOLIATION

摘要

Two-dimensional nanosheets usually show excellent electrochemical performance due to an increase in surface area and shorter diffusion paths. However, the 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 LiCoO_2, LiMn_2O_4, and Li_5Ti_4O_(12) were chemically exfoliated and investigated using electron energy loss spectroscopy (EELS) for their Li-K edge. Further analyses were carried out, looking at its oxygen (O) K edge with their respective transition metal core loss peak (Mn, Co and Ti) which indicated charge transfer from lithium. Statistical analyses were carried out on the exfoliated LiCoO_2 at different centrifuging speeds, in order to reveal different percentages in lithium content. It is also extremely important to note that the 2-D exfoliated materials are much more sensitive to beam damage which makes it even harder to pick up the characteristic signals of lithium.