In this paper, we describe how the mechanism of formation of a protective film [the solid electrolyte interphase (or interface) (SEI)] on a graphite electrode for Li-ion batteries was investigated from the novel perspective of precipitation of the final decomposition products that arise from the reduction of a nonaqueous electrolyte solution in contact with the graphite electrode. Within the framework of this new perspective, we can elegantly account for the compositional and structural differences between the basal-plane and edge-plane SEIs and for the origins of the multi-layer structure and the parabolic growth law of the SEIs on both the edge-plane and basal-plane surfaces of the graphite electrode. (C) 2009 Elsevier Ltd. All rights reserved.