Anode Performance of Vapor‐Grown Carbon Fibers in Secondary Lithium‐Ion Batteries

Abstract

Chopped vapor‐grown carbon fibers (VGCFs) were studied as anodes for secondary lithium ion batteries using a in a 1:1 (by volume) mixture of ethylene carbonate (EC) and diethylcarbonate (DEC) electrolyte. VGCFs were prepared from hydrocarbons by a vapor‐grown method and chopped to ca. 10 μm length. Three different diameters of the VGCFs, 1, 2, and 3 μm (1GWH, 2GWH, and 3GWH, respectively) were used. The VGCFs chopped after graphitization (the 2A method‐VGCFs) displayed a higher capacity than those chopped before (the 1A method‐VGCFs). In particular, 2GWH‐2A gave a capacity of carbon, 1.6‐fold higher than the capacity of 2GWH‐1A; this is almost equal to the theoretical intercalation capacity of an ideal graphite . The cyclic voltammogram of 2GWH‐2A showed the most significantly different profile from that of natural graphite among all of the VGCFs. It is suggested that a new structural change is induced in the well‐graphitized VGCFs during the chopping process that affects the lithium storage reaction.