The detection of elemental content changes in electrode coating using laser-induced breakdown spectroscopy

The elemental content of battery electrode coating is prone to change due to the production technology and ambient factors. To ensure the consistent performance and safety of a lithium battery, the elemental content of the electrode coating needs to be kept strictly consistent. This study proposes an internal mixed matrix method that combines laser-induced breakdown spectroscopy and chemometric method to achieve rapid and accurate detection of elemental content changes in electrode coating. The stoichiometric ratios of analytical elements are calculated by using the spectra of laser-induced breakdown spectroscopy. The relationships between that stoichiometric ratios and the actual content of analytical elements are studied and show that they are linear. Thus, the content change of the analytical element can be determined by calculating the change of the stoichiometric ratio. The average relative errors for content changes of iron, lithium, and phosphorus are 6.43%, 2.96%, and 4.12%, respectively, and the lowest detection limits are 278.2 mg/kg, 20.5 mg/kg, and 105.4 mg/kg, respectively. Furthermore, the internal reference method is proposed to correct the effect of ambient gases and improve detection accuracy. The results are that when Fe I 372.751 nm and Fe I 373.485 nm are used as analytical lines, after correcting for the effect of ambient gases, the average relative errors of Fe content changes are reduced by 62% and 72%, respectively, and the lowest detection limits are increased by 67% and 71%, respectively.