Controllable Synthesis of TiO2/Graphene Nanocomposites for Long Lifetime Lithium Storage: Nanoparticles vs. Nanolayers

This work reported controllable synthesis of TiO2/graphene nanocomposites with various morphologies by a one-pot one-step solvothermal method and tested their lithium storage performance. In the absence of glucose, TiO2 nanolayers grafted graphene with low crystallinity were obtained. In the presence of glucose at a low content, TiO2/graphene was composed with well-dispersed nanoparticles and has high crystallinity of TiO2, while at a high content of glucose, TiO2/graphene was a mixture of hierarchical TiO2 microspheres and graphene covered with amorphous carbon. As a result, these TiO2/graphene nanocomposites went through different mechanisms of lithium ions insertion/extraction due to their different particle sizes and crystal structures. Compared with the ultrathin layers and microspheres morphologies, TiO2 nanoparticles/graphene demonstrated high reversible capacity (>260mAhg−1 at 0.1C, C=168mAg−1), long-term cycling ability at 1C (1000 cycles, retention 83%) and superior rate capability from 0.1C to 10C, and still delivers a high capacity of 154mAhg−1 after 1000 cycles even at 2C. The superiority of TiO2 nanoparticles/graphene benefits from the combination of small particle size (<10nm), high dispersion, mesoporous structure, and improved electronic conductivity. The findings in this work will advance the design of functional materials for energy storage.