Electrochemical SPM investigation of the solid electrolyte interphase filmformed on HOPG electrodes

Solid electrolyte interphase (SEI) film formation on graphite electrodes wa s studied on highly oriented pyrolytic graphite (HOPG) in nonaqueous electr olyte by in situ electrochemical atomic force microscopy (AFM). For potenti als negative to 0.7 V versus Li\Li+ a SEI film is formed on the HOPG electr ode surface. After the first cycle the film is rough and covers the surface of the HOPG electrode only partially. After the second cycle the HOPG surf ace is fully covered by a compact film. The thickness of the SEI film was m easured by increasing the pressure of the AFM tip and thus scraping a part of the electrode surface. In this way a thickness of about 2.5 nm was found for the SEI film formed after two scan cycles between 3 and 0.01 V versus Li\Li+. (C) 2000 Elsevier Science S.A. All rights reserved.