X-ray photoemission studies of surface pre-treated graphite electrodes

Surface pre-treatment of graphitic electrode materials for lithium ion cell s has recently been shown to significantly reduce the irreversible consumpt ion of material and charge due to the formation of the so-called solid elec trolyte interphase, during battery charging. In this paper we compare graph ite powders and carbon fibres as model materials for studies of the effects of CO2 pre-treatments on solid electrolyte interphase (SEI) formation usin g X-ray photoemission spectroscopy (XPS). We observe significant modificati on in the surface elemental composition as a function of CO2 treatment temp erature for carbon fibres, but no strong changes for graphite powders. We c onclude that the predominance of the relatively unreactive basal plane in t he surface area of the powders makes them far less suitable for detailed XP S studies than the fibres, where the more reactive prismatic planes predomi nate. (C) 2001 Elsevier Science B.V. AU rights reserved.