Nondestructive Chemical Mapping of Lithium on/in a Graphite Electrode via X-ray Raman Scattering Spectroscopy

Lithium (Li) metal plating in lithium-ion batteries (LIBs) poses critical challenges for fast charging, contributing to capacity fading and safety concerns. Addressing this issue requires the development of nondestructive tools that can characterize the inhomogeneity of Li in batteries. Here, we demonstrate X-ray Raman scattering (XRS) spectroscopy as a powerful new technique for the characterization of Li in LIBs. Using spatially resolved XRS, we analyzed a graphite electrode subjected to rapid charge-discharge cycling, which induced Li metal deposition, and for the first time, successfully mapped the chemical state of Li on and inside the graphite electrode. Importantly, the XRS method enabled nondestructive detection of both deposited Li metal and Li species within the electrode sealed in Al-laminated films. This operando-compatible methodology offers a pathway for obtaining deep mechanistic insights into Li behavior in LIBs.