Graphene/Na carboxymethyl cellulose composite for Li-ion batteries prepared by enhanced liquid exfoliation

摘要

In the present work, we report a sonication-assisted exfoliation method of graphene preparation enhanced by the use of microwave heating and "green" exfoliant - sodium carboxymethyl cellulose (NaCMC). Introducing microwave heating during sonication of graphite dispersions in aqueous solutions of NaCMC results in the formation of graphene dispersions with concentration as high as 4.29 mg/ml. It is found that drying the dispersions results in the formation of graphene/NaCMC composites with graphene content up to 38.65 wt%. A study of the composite with High Resolution Transmission Electron Microscopy and Raman Spectroscopy reveals the formation of few-layer graphene approximately below five layers. The as-prepared graphene/NaCMC composite shows higher capacities than commercial graphite in Li-ion half cells reaching 397 mAh/g_((graphene)). Also, when the composite is used with a nanosilicon (33 wt%) in a Li-ion half cell high initial reversible capacities of 1611 mAh/g_((si)) with good cyclability and rate capability have been reached.