2-Phenylimidazole as an additive to prevent the co-intercalation of propylene carbonate in organic electrolyte for lithium-ion batteries

2-Phenylimidazole (PID), which is structurally different from previously reported compounds, has been studied as a film-forming additive for graphite anode in PC-based electrolyte for lithium-ion batteries. A 1.0 mol l(-1) LiPF6/PC: DMC (1:1, v/v) electrolyte containing 3 wt.% 2-phenylimidazole was capable of suppressing the co-intercalation of PC and inhibiting the decomposition of electrolytes during the first lithium intercalation. The cyclic voltammogram shows that the reduction potential of PID is about 1.65 V vs. Li/Li+, forming a favorable solid electrolyte interface (SEI) on the graphite electrode. The morphologies and the chemical composition of the graphite electrode surface were characterized by SEM and XPS. The results show that a stable SEI film was formed on the surface of graphite by the addition of PID, which accounts for the excellent cycleability of the graphite electrode in PC-based electrolyte. (C) 2008 Elsevier B.V. All rights reserved.