Surface-Enhanced Raman Spectroscopy for Lithium Battery Interfaces.
The electrode/electrolyte interface has a significant impact on the performance of lithium batteries. At the interface, the charged electrode surface, electric double layer (EDL), and solid electrolyte interphase/cathode electrolyte interphase (SEI/CEI) change with voltage, electrolyte, and surface structure. Although post-cycling characterization can identify many interfacial products, it is often difficult to determine when these species form or how they change during charge and discharge. Surface-enhanced Raman spectroscopy (SERS) can detect interfacial Raman signals, allowing specific electrolyte components, intermediates, and interfacial products to be monitored under operating conditions. This review discusses the application of SERS in studies of lithium battery interfaces, including SERS enhancement mechanisms and substrate structures. Typical applications of SERS are summarized for anode interfaces, cathode interfaces, and Li-O2/Li-CO2 cathodes, including SEI formation, EDL-regulated interfacial chemistry, Li plating/stripping, high-voltage CEI formation, oxygen-related surface reactions, and gas-cathode intermediates. Finally, we discuss how SERS can be extended to less-studied interfaces, combined with other characterization techniques, verified by computational methods, and applied under more practical battery conditions.