Characteristics of a Graphene Nanoplatelet Anode in Advanced Lithium-Ion Batteries Using Ionic Liquid Added by a Carbonate Electrolyte

A Cu-supported, graphene nanoplatelet (GNP) electrodes are reported a as high performance anode in lithium ion battery. The electrode precursor is an easy-to-handle aqueous ink cast on cupper foil and following dried in air. The scanning electron microscopy evidences homogeneous, micrometric flakes-like morphology. Electrochemical tests in conventional electrolyte reveal a capacity of about 450 mAh g-1 over 300 cycles, delivered at a current rate as high as 740 mA g-1. The graphene-based electrode is characterized using a N-butyl-N-methyl-pyrrolidiniumbis (trifluoromethanesulfonyl) imide, lithium-bis(trifluoromethanesulfonyl)imide (Py1,4TFSI-LiTFSI) ionic liquid-based solution added by ethylene carbonate (EC): dimethyl carbonate (DMC). The Li-electrolyte interface is investigated by galvanostatic and potentiostatic techniques as well as by electrochemical impedance spectroscopy, in order to allow the use of the graphene-nanoplatelets as anode in advanced lithium-ion battery. Indeed, the electrode is coupled with a LiFePO4 cathode in a battery having a relevant safety content, due to the ionic liquid-based electrolyte that is characterized by an ionic conductivity of the order of 10-2 S cm-1, a transference number of 0.38 and a high electrochemical stability. The lithium ion battery delivers a capacity of the order of 150 mAh g-1 with an efficiency approaching 100%, thus suggesting the suitability of GNPs anode for application in advanced configuration energy storage systems.