Critical Role of Silicon Nanoparticles Surface on Lithium Cell Electrochemical Performance Analyzed by FTIR, Raman, EELS, XPS, NMR, and BDS Spectroscopies

A pluri-disciplinary approach and a combination of techniques are used here to finely describe the surface of silicon nanoparticles used as active material in negative composite electrodes for lithium batteries. Although the surface of silicon particles is playing a major role in the electrochemical performance, it has rarely been characterized in depth. With respect to infrared analysis, we propose an analytical protocol, derived from the studies devoted to high specific area silica samples. Three different nanometric silicon powders are studied: a commercial one and two home synthesized silicon powders with specially designed surfaces. With respect to previous works and common belief, we demonstrate, on the electrochemical performance, a favorable effect of a particular thin layer silicon oxide with a well-defined SiO2 composition at the extreme surface of the silicon particles.