The propensity of lithium dendrite formation during the charging process of lithium metal batteries is linked to inhomogeneity on the lithium surface layer. The high reactivity of lithium and the complex surface structure of the native layer create "hot spots" for fast dendritic growth. Here, it is demonstrated that a fundamental restructuring of the lithium surface in the form of lithium silicide (Li Si) can effectively eliminate the surface inhomogeneity on the lithium surface. In situ optical microscopic study is carried out to monitor the electrochemical deposition of lithium on the Li Si-modified lithium electrodes and the bare lithium electrode. It is observed that a much more uniform lithium dissolution/deposition on the Li Si-modified lithium anode can be achieved as compared to the bare lithium electrode. Full cells paring the modified lithium anode with sulfur and LiFePO cathodes show excellent electrochemical performances in terms of rate capability and cycle stability. Compatibility of the anode enrichment method with mass production process also offers a practical way for enabling lithium metal anode for next-generation lithium batteries.

In this letter, the ultrafast vibrational dynamics of individual gold nanorings has been investigated by femtosecond transient absorption spectroscopy. Two acoustic vibration modes have been detected and identified. The influence of the mechanical coupling at the nanoparticle/substrate interface on the acoustic vibrations of the nano-objects is discussed. Moreover, by changing the environment of the nanoring, we provide a clear evidence of the impact of the surrounding medium on the damping of the acoustic vibrations. Such results are reported here for the first time on individual nanoparticles. This work points out a new sensing method based on the sensitivity of the acoustic vibration damping to the surrounding medium.

This work is devoted to the fundamental understanding of the interaction between acoustic vibrations and surface plasmons in metallic nano-objects. The acoustoplasmonic properties of coupled spherical gold nanoparticles and nanodisk trimers are investigated experimentally by optical transmission measurements and resonant Raman scattering experiments. For excitation close to resonance with the localized surface plasmons of the nanodisk trimers, we are able to detect several intense Raman bands generated by the spherical gold nanoparticles. On the basis of both vibrational dynamics calculations and Raman selection rules, the measured Raman bands are assigned to fundamental and overtones of the quadrupolar and breathing vibration modes of the spherical gold nanoparticles. Simulations of the electric near-field intensity maps performed at the Raman probe wavelengths showed strong localization of the optical energy in the vicinity of the nanodisk trimers, thus corroborating the role of the interaction between the acoustic vibrations of the spherical nanoparticles and the surface plasmons of the nanodisk trimers. Acoustic phonons surface enhanced Raman scattering is here demonstrated for the first time for such coupled plasmonic systems. This work paves the way to surface plasmon engineering for sensing the vibrational properties of nanoparticles.

No abstract