In situ surface-enhanced Raman spectroelectrochemistry reveals the molecular conformation of electrolyte additives in Li-ion batteries

J Mater Chem A Mater. 2021 Aug 2;9(35):20024-20031. doi: 10.1039/d1ta04218a. eCollection 2021 Sep 14.

ABSTRACT

We report the mechanism of rhodamine B (RhB) acting as an electrolyte additive in Li/graphite cells. We show that the cycle performance and rate capability of graphite are enhanced in carbonate-based electrolytes containing 0.2 wt% RhB. By using silica-encapsulated Au nanoparticles, in situ surface-enhanced Raman spectroscopy (SERS) is applied to study the graphite/electrolyte interface. We find that the adsorption orientation of RhB molecules on the surface of graphite can be modulated by the applied potential: vertical adsorption at higher potentials while horizontal adsorption takes place at lower potentials. This behavior effectively suppresses the electrolyte solvent decomposition, as well as electrode corrosion while improving the Li+ diffusion. This work shows that SERS is a powerful tool for interfacial analysis of battery systems and provides new ideas for rational design of electrolyte additives.

PMID:34589227 | PMC:PMC8439146 | DOI:10.1039/d1ta04218a

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