(617d) Gold Nanoparticle Monolayers for Surface-Enhanced Raman Spectroscopy of Lithium Batteries

Lithium battery safety and quality are largely limited by contamination and side reactions that lead to capacity fade or even hazardous runaway conditions. Electrochemical reactions are exceptionally sensitive to trace contamination that is difficult to detect with spectroscopic methods. Reliable performance of a battery relies on extremely thin passivation layers that form between electrodes and electrolyte. We have developed a substrate for surface-enhanced Raman spectroscopy (SERS) that enables detection at concentrations relevant for studying battery contamination and passivation layers. SERS relies on surface plasmon resonance to enhance Raman scattering by many orders of magnitude. It has traditionally suffered from lack of reproducibility due to lack of control of surface structure. We report a self-assembly technique to prepare gold nanoparticle monolayers with reproducible long-range hexagonal structure. Our approach allows for precise control of particle size and spacing, which are important for Raman enhancement. We report the performance of our substrates with model analytes and with components used in lithium batteries.