Ultrasonication fabrication of high quality multilayer graphene flakes and their characterization as anodes for lithium ion batteries

Ultrasonication of graphite nanoplatelets for 10 min to 10 h produced multilayer graphene flakes (GFs) with average lateral sizes of 4.5–1.0 μm and as few as four stacked layers. Raman and X-ray photoelectron spectroscopies of GFs fabricated using a short sonication time (1 h) indicated that their qualities were quite high, probably due to a low level of introduced defects and their presence mainly at the edges of the GFs. Characterization of GFs used as the anodes of lithium ion batteries revealed a large reversible capacity of 597 mAh/g in the first cycle and a good cycle characteristic in the second to tenth cycles. Unlike the reported behaviors of graphene nanosheets and nanoribbons, reversible lithiation and delithiation were governed by intercalation and deintercalation.