Direct and Indirect Observation of Lithium in a Scanning Electron Microscope; Not Only on Pure Li!

Battery is one of the most used technologies in everyday life (cellular, electric vehicle or hybrid cars). Improvement in the specific capacity (energy by weight or volume) and charging rate has a potential to even significantly improve their used. Hence, the research in battery materials is very important, well founded and will have a direct economical and social impact. Most of the actual battery technology is based on the displacement of Lithium ion (Li) from two active materials (i.e., graphite for the anode and LiFePO4 for the cathode). It is thus essential to determine the distribution and the amount of Li with a good spatial resolution (<< 1 μm) In terms of microstructural characterization Li is very difficult to analysed using conventional detector because it is a very light element and emits low energy x-rays (52 eV). Optical Emission spectrometry and XPS can easily detect Li but without any no good lateral resolution. In counterpart, Li has a relatively high sputtered yield and low backscattered coefficient. Mass spectra have been used in dedicated secondary ion mass microscope (SIMS), either static or Time of Flight (TOF) but with, again, with a limited lateral resolution.