Lithium quantification using the composition-by-difference method
Instruments used
The OnPoint™ detector and EDAX® Octane Elite Super EDS system were used in combination to determine the lithium concentration in a stoichiometric lithium oxide sample.
Background
Lithium (Li)-ion based batteries have been adopted in electrochemical cells due to their capacity for energy storage at high-energy densities and lighter mass compared to other technologies. However, there remains a significant requirement for a characterization technique that allows the microscale distribution of Li to be determined. Commonly used microanalysis techniques in the scanning electron microscope (SEM) such as energy- or wavelength-dispersive x-ray spectroscopies (EDS or WDS) cannot be applied to low atomic number elements (Z ≤3), including lithium due to the dependence of the fluorescence yield on bonding state and likelihood of x-ray re-absorption [P. Hovington et al., Scanning 38 (2016) p571–578]. However, recent work on metallic alloys demonstrated quantitative analysis of Li in the SEM with ~1 wt.% accuracy using the lithium by composition-by-difference method (Li-CDM) [JA. Österreicher et al., Scripta Materialia 194 (2021) 113664]. In the Li-CDM, the EDS and backscattered electron (BSE) signals are recorded quantitatively, allowing the lithium content to be determined through computation. Here, we extend this approach to materials of known stoichiometry, determining the Li content of lithium aluminate (LiAlO2) with an accuracy better than 1.0 wt.%.