Synthesis of MnO/reduced graphene oxide composites as high performance anode materials for Li-ion batteries

MnO/reduced graphene oxide (MnO/rGO) composites synthesized through freeze-drying following annealing were used as anode materials for lithium ion batteries. At 500 mA·g^-1, the MnO/rGO composite exhibits a reversible capacity as high as 830 mAh·g^-1 and the specific capacitance remains at 805 mAh·g^-1 after 160 discharge/charge cycles, demonstrating excellent cycling stability. It also shows good rate capacities and delivers a specific capacity of 412 mAh·g^-1 at 2. 0 A·g^-1 after 225 cycles at different rates. The rGO increases the electrical conductivity and provides space to accommodate the volume expansion of MnO during charge/discharge. The extra capacity, over the theoretical value of MnO, is attributed to the formation of higher oxidation state manganese according to the charge-voltage derivative analysis of the galvanostatic charge-discharge curves. A higher tendency to further oxidize Mn(Ⅱ) in the MnO/rGO composite maybe result in the extra oxygen source provided by rGO during the electrode reaction. The simple and green synthetic protocol and the excellent electrochemical performance demonstrate the great potential of the MnO/rGO composite anode in large scale production and applications.