Characterization of element distribution and thickness change in a high-capacity lithium-ion battery unit cell before and after charging via laser-induced plasma spectroscopy

The characterizations of the multi-layered cathode, separator, and anode as a single unit of commercial-grade high-nickel-based lithium-ion batteries (LIBs) are carried out to identify three-dimensional elemental distribution and to measure the electrode thickness change before and after being fully charged by using the laser-induced plasma spectroscopy (LIPS). It is found that, in addition to alterations in Li-ion concentration, the emission intensities in structural elements such as nickel in the cathode. Carbon in the anode also changed when the LIBs are charged to 100%, due to increased electron density from higher concentrations of easily ionized elements. Moreover, after charging, the contraction of the cathode and expansion of the anode are observed by correlation analysis of the depth-resolved plasma emission spectra. It is also revealed that the cathode thickness reduction caused by Li-ion deintercalation is smaller than the anode thickness expansion. Overall, the Li-ion structural units expand after charging. Unlike other approaches for measuring electrode thickness in LIBs, this study utilized LIPS mapping to uncover the electrode thickness changes. Thus, a simple and high-throughput method is explained for identifying the elemental and structural variations of high-nickel-based LIBs before and after charging.