Additives of Graphene Nanosheets on the Anode Performance of Spherical Natural Graphite for Lithium-Ion Batteries

摘要

A comparison was carried out on carbon black and graphene nanosheets as conducting additives in spherical natural graphite for lithium ion batteries. Graphene nanosheets were synthesized by electrochemical intercalation and microwave exfoliation. High-resolution transmission electron images show that the graphene nanosheets were made up of 10-12 graphenes. Scanning electron microscopy images showed that graphene nanosheets covered the graphite particles and carbon black conglomerated in the interspace among graphite particles. The electrochemical impedance spectra showed that the addition of graphene nanosheets reduced the charge transfer resistance more effectively than carbon black. The reversible capacity of natural graphite mixed with graphene nanosheets increased to 366 mAh/g and the cycle stability improved to 97percent, proving that the addition of graphene nanosheets was more effective to improve the electrochemical capacity of Li~(+) insertion/de-insertion compared to carbon black.