Co3O4/nitrogen modified graphene electrode as Li-ion battery anode with high reversible capacity and improved initial cycle performance

Co3O4 nanoparticles are grown on nitrogen modified microwave exfoliated graphite oxide (NMEG) with weight ratio controlled from 10% to 70%. Electrochemical performance reveals that the obtained Co3O4/NMEG composite as Li-ion battery anode exhibits improved cycle stability, excellent reversible capacity, high current rate performance, and reduced irreversible capacity toss in the initial cycle compared to pure Co3O4 without graphene or Co3O4 on thermally reduced graphene oxide (tRG-O). The 70%Co3O4/NMEG composite has initial irreversible capacity of 230 mAh g(-1) (first cycle efficiency of 77%), and 910 mAh g(-1) of capacity is retained after 100 cycles. The 70%Co3O4/tRG-O delivers a reversible capacity of 750 +/- 20 mAh g, and the irreversible capacity loss during the first cycle is 700 +/- 20 mAh g(-1). Nitrogen functional groups in NMEG, especially pyridinic and pyrrolic N are advantageous for the Co3O4 growth. Furthermore, the N modification is effective in reducing the oxygen content of chemically prepared graphene and hence is good for Co3O4 dispersion and the amelioration of first cycle efficiency, demonstrating the potential of NMEG based composite as high performance Li-ion battery anode materials. (C) 2013 Elsevier Ltd. All rights reserved.