Sn/C nanocomposites were synthesized by thermal decomposition of precursor mixtures comprising SnO2 and gluconic acid (GA). The resulting Sn/C material is composed of Sn nanoparticles (60-100 nm) embedded within a carbonaceous matrix. The effect of electrolyte composition and the initial charging break-in current density on the formation and stability of the solid electrolyte interphase (SEI) has been studied and discussed under varying solutions of ethyl-, dimethyl-and vinylene-carbonates. A thin and stable SEI of high ionic conductivity is formed by reduction of vinylene carbonate at increased break-in current densities as high as 800 mA g(-1). It is proposed that a certain amount of inserted Li species forms a stable LiSn adduct during the initial charging period, which acts as the substrate phase into which Li+ is reversibly and efficiently inserted. The Sn/C nanocomposite interphased with a solvent containing 10% vinyl-carbonate delivers a reversible and stable capacity of 400 mAh g(-1) for over 200 cycles. (C) 2016 The Electrochemical Society. All rights reserved.