The use of in-situ Raman spectroscopy in investigating carbon materials as anodes of alkali metal-ion batteries

Raman spectroscopy is a fast, non-destructive and high-resolution characterization tool based on laser physics that can be applied to a wide range of materials science problems. It has proven to be an effective tool in studying phase transitions induced by variables such as temperature, pressure or electrochemical reactions. In-situ Raman spectroscopy can be used to track any microstructural changes of the electrode materials and interface reactions in alkali metal-ion batteries during charging and discharging. Carbon materials have become the most widely used anode materials for lithium-ion batteries because of their good electrochemical reversibility, excellent stability, low electrochemical charge/discharge potential platform, and low cost. The use of in-situ Raman spectroscopy in understanding the reactions occurring in alkali metal-ion batteries using carbon anode materials is summarized with a focus on the energy storage mechanism in Li⁺/Na⁺/K⁺ ion batteries using carbon materials such as graphite and hard carbon as the anode materials. The effects of size, stress, doping, and the solvation-assisted co-intercalation of Li⁺/Na⁺/K⁺ ions on the energy storage behavior in alkali metal-ion batteries are analyzed. Based on the strength and weakness of in-situ Raman spectroscopy, its combination with AFM, in situ XRD and other high-resolution in situ technologies is used to reveal the energy storage mechanisms.