Lithium storage properties of graphene sheets derived from graphite oxides with different oxidation degree

Electrochemical properties of graphene sheets (GSs) for lithium ion batteries were investigated. GSs were prepared from graphite through oxidation followed by rapid thermal exfoliation. To synthesize graphite oxides (GOs) with different oxidation degree, the number of times of oxidation of graphite was controlled from 1 to 3 times. GSs electrodes derived from 1, 2 and 3 times oxidized GOs exhibited a high charge capacity of 1252, 1793 and 2311 mAh g−1, respectively, at the 20th cycle at a current density of 100 mA g−1. As the oxidation degree of GO increased, the reversible capacity of GSs was enhanced. The enhanced capacity is assumed to be due to increased surface area and additional lithium storage sites such as defects and edges.