Observation of a LiCoO2 Cathode Material of a Li-Ion Battery by High Spatial ResolutionTOF-SIMS

Lithium (Li)-ion batteries will be important to future generations for use as clean energy-storage devices. However, the surface chemical reaction mechanism of the electrode has not been revealed to date. In this study, surface observation and chemical species mapping of cathode material for the Li-ion batteries were performed using a laboratory-made time-of-flight secondary ion mass spectrometry (TOF-SIMS) apparatus. The most notable feature of this apparatus is its high-spatial resolution (similar to 40 nm), which is achieved by employing a focused ion beam. In order to reveal the spatial distributions of chemical species on the LiCoO2 cathode material, we applied the new TOF-SIMS measurement. Differences in the distribution of molecular species on the crystal face were observed with this apparatus.