Deficiencies of Chemically Reduced Graphene as Electrode in Full Li-Ion Cells

Abstract

In spite of the good electrochemical performance of graphene as electrode vs. lithium (half-cell configuration), graphene does not work in a full Li-ion cell as the delivered capacity continuously fades on cycling. The high irreversible capacity (IC) of the electrode observed in the former configuration, which is caused by the solid-electrolyte interface (SEI) formation, can be one of the causes of this shortcoming. As a remedy to this drawback, the graphene electrode was subjected to a lithiation process to form the SEI before assembling the full cell. Two lithiation methods were implemented: 1) precycling the electrode vs. a Li foil, and 2) placing the electrode in contact with a Li foil that was wetted with the electrolyte. Both methods improved the performance of the full cell, particularly the contact treatment, but the capacity retention on cycling was moderate. Moreover, not only does the electrode activation govern the electrochemical response, but factors such as the synthesis method and particle dimensions can also affect the cell performance.