Advanced Spectroelectrochemical Techniques to Study Electrode Interfaces Within Lithium-Ion and Lithium-Oxygen Batteries.

Lithium battery technologies have revolutionized mobile energy storage, but improvements in the technology are still needed. Critical to delivering new light weight, high capacity, safe devices is an improved understanding of the dynamic processes occurring at the electrode-electrolyte interfaces. Therefore, alongside advances in materials there has been a parallel progression in advanced characterization methods. Herein, recent developments for operando spectro-electrochemical techniques centered on Raman, infrared, and sum frequency generation are described within the context of lithium-ion and non-aqueous lithium-oxygen battery research. In particular, shell-isolated nanoparticles for enhanced Raman spectroscopy (SHINERS), surface-enhanced infrared absorption spectroscopy (SEIRAS), and near-field infrared are explained and critically evaluated, and future opportunities discussed. The aim is to introduce the wider community to the developing range of methodologies and tools now available in the hope that it encourages greater usage across the sector.