A new approach to surface properties of solid electrolyte interphase on a graphite negative electrode

389We have developed a new technique capable of measuring the thickness of SEI layer on graphite anode, and the surface morphological properties under low acceleration voltage was investigated by XHR-SEM. The XHR-SEM under low acceleration voltage with low energy induced ion etching in XPS studies have provided valuable information on SEI layer formation. The spongy-type layer of the SEI may comprise the organic and/or inorganic components of the complex compact/porous structures. The outermost surface of the SEI layer shows quite different features compared with the inner part of those SEI layers. The spongy-type layer could be composed of the compact inner layer (10-15 nm) and the porous outer layer (20-30 nm).