Electrochemical and safety characteristics of TiP2O7agraphene nanocomposite anode for rechargeable lithium-ion batteries

This paper reports a co-precipitation synthesis of TiP2O7agraphene (10 wt%) nanocomposite and pure TiP2O7 nanoparticles for the use as an advanced anode material for high performance lithium-ion batteries. The structure and morphology of the compounds are characterized by powder X-ray diffraction, field-emission scanning electron microscopy and field-emission transmission electron microscopy techniques. The electrochemical performances were evaluated in coin type Li-ion test cells. This TiP2O7agraphene nanocomposite displayed superior Li-ion battery performance with a large reversible capacity, excellent cyclic performance and good rate capability at a current density of 0.1 mA cma2. At an elevated current density of 6.4 mA cma2, the nanocomposite anode delivered a capacity of 98.4 mAh ga1, which is much higher than that of pure TiP2O7 (0.56 mAh ga1). The impressive electrochemical performance of the nanocomposite was ascribed to the synergistic effect of the high surface area nanoparticles in conjunction with the good electronic conductivity of graphene. The graphene nanosheets not only provide an electronically conducting network, but also tend to prevent the aggregation of the high surface area TiP2O7 nanoparticles. Further, the graphene nanosheets can act as buffer layers to accommodate the volume change during the Li-ion insertion/extraction processes in the TiP2O7 nanoparticles.