Battery characterization method could enable higher performance electric vehicles

Lithium-ion batteries have paved the way for portable electronics and electric vehicles, but further improving their performance requires scientists to understand their electrochemistry at all scales, because it evolves during battery operation. Meng et al. combined two techniques to characterize battery electrochemistry in situ, enabling the study of these dynamic and complex changes and their relationships.

The team merged atomic force microscopy (AFM), a technique used to characterize the surface topographies of electrode materials at a high spatial resolution, with Raman spectroscopy, a non-destructive and ultrasensitive technique that characterizes chemical composition, structural changes, and phase transitions. Linking these phenomena to their observed electrochemical properties will help characterize the structure-property relationships of lithium-ion batteries.

“The novel design is capable of accommodating a water-immersion objective for high sensitivity Raman detection in the reflection mode, an optical lever detection for AFM imaging, and a dual-cell for effectively avoiding the objective contamination from the electrolyte during electrochemical reaction,” author Zhuanfang Bi said.

To demonstrate their system’s ability to obtain AFM images and Raman spectra simultaneously during battery operation, the team applied a linear sweep voltage to an electrode made of the battery material lithium manganese oxide in an electrolyte solution. They identified voltages corresponding to transition points, like removal and addition of lithium ions, and analyzed the AFM images and Raman spectra obtained at those voltages. Results indicated the lithium material changed in size and structure, and those changes were correlated, which validates the technique.

The authors plan to continue improving the spatial resolution and sensitivity of their system.

Source: “A novel design for the combination of electrochemical atomic force microscopy and Raman spectroscopy in reflection mode for in-situ study of battery materials,” by Xiaoxia Meng, Zhuanfang Bi, Xinru Wang, and Guangyi Shang, Review of Scientific Instruments (2022). The article can be accessed at https://doi.org/10.1063/5.0096766 .