A series of butyrolactone derivatives with various side chains mainly at the 5-position were used as additives in 1 M LiClO4-propylene carbonate (PC) electrolyte for lithium-ion batteries with graphite anodes. When more than 0.3 M of 2-acetyloxy-4,4-dimethyl-4-butanolide (AcBL1) was added to 1 M LiClO4-PC solution, exfoliation of graphite, co-intercalation and decomposition of PC was suppressed and lithium insertion and extraction into/from graphite anode proceeded. C-13 NMR measurements suggested that the suppression of PC co-intercalation and decomposition was due to the decrease of the number of PC molecules coordinated to the lithium ion and increase of AcBLI coordination. Addition of butyrolactone derivatives with acetoxyl or carbonate groups at the 5-position into 1 M LiClO4-C solution led to better charge-discharge anode performance. (C) 2003 Elsevier Science B.V. All rights reserved.