Graphene nanosheets (GNS) with attached MnOx nanoparticles are studied in regard to their structure and morphology. The relationship between the lithium storage performances and GNS contents as well as manganese valency was investigated. Experimental results showed that the specimen with 44 wt% GNS and high content of MnO delivered high reversible capacity (over twice of that in graphitic carbon anode), good cycling stability (0.8% fading per cycle), and high rate capability (67% at the 800 mA/g), which are dramatically better than pure Mn3O4. The improvement is attributed to the presence of GNS which provides continuous networks for fast electronic conduction and mechanical flexibility for accommodating the large volume change. The MnOx/GNS hybrid material has the added advantages over pure GNS, benefiting from its lithium storage potential of around 0.5 V which not only ensures high rate capability but also reduces the risk of metallic lithium formation with its safety hazard.

Improvements of the anode performances in Li-ions batteries are in demand to satisfy applications in transportation. The emerging new class of materials -nano graphene platelets (NGPs) and their composites -are promising alternative anodes. In this paper, a brief review was presented focusing on the high-capacity lithium storage characteristics in pyrolyzed carbons and carbon nanotubes as well as the computational results on lithium -graphene interactions and diffusion. These results led to the research towards both high lithium storage capacity and rapid lithium kinetics in NGPs. Afterwards, experimental results on lithium storage characteristics in three different kinds of NGPs were presented. High reversible capacities and rate capabilities were achieved in the NGPs. Some comments on the necessity and feasibility of mechanistic studies on lithium storage in graphenebased nanomaterials were also addressed.

In comparison with graphitic carbons, graphene oxide and transition metal oxides can reversibly store/release over twice amount of lithium per mass. In this research, lithium storage characteristics in graphene oxide (GO) and GO/manganese oxide (GO/Mn 3 O 4 ) composites were studied, which are advantageous in terms of low cost and environmental benign. The prepared GO delivered reversible capacity of 790 mAh/g with an average columbic efficiency of 95%. The capacity decreased dramatically after GO was thermally annealed 400°C resulting from the 3D stacking of graphene layers into the turbostratic misalignment. The GO/Mn 3 O 4 composites exhibited reversible capacities up to 860 mAh/g based on the total mass, corresponding to 900 mAh per gram of Mn 3 O 4 close to theoretical value. The high reversible capacities and good cyclic stability of the GO/Mn 3 O 4 composites can be attributed to the formation of nano size particles of Mn 3 O 4 and enhanced electronic and mechanical properties in the presence of graphene.