The effects of a solid electrolyte interface (SEI) additive, triacetoxyvinylsilane (VS), on the electrochemical performance of a lithium metal secondary battery were investigated. When 2 wt % VS was added to the electrolyte, no lithium dendrite on the lithium metal surface after precycling was observed and thereby the lowest interfacial resistance of the unit cell (LiCoO2/ Li) could be achieved. With these reasons, the capacity of the unit cell based on the electrolyte containing 2 wt % VS could maintain about 0% of the initial capacity after 200 cycles at a high charge/ discharge current density (C/2, 1.25 mA cm(-2)). (c) 2007 The Electrochemical Society.