Graphene-Modified TiO2 Microspheres Synthesized by a Facile Spray-Drying Route for Enhanced Sodium-Ion Storage

Abstract

A TiO2@reduced graphene oxide (TiO2@rGO) composite is synthesized successfully by a simple spray-drying method. The structural and morphological characterizations reveal that the TiO2@rGO composite has a sphere-like morphology with diameters of 5–15 µm, and each microsphere is actually a random aggregation of primary TiO2 nanoparticles, which are tightly covered by soft graphene sheets. The TiO2@rGO electrode exhibits enhanced electrochemical performance of high charge capacity (170 mA h g−1 at 0.1 C), long cycling life (87% of capacity retention after 300 cycles at 0.2 C), and high rate capability (55 mA h g−1 at 10 C). Compared with bare TiO2 microspheres, the improved electrochemical performance of the TiO2@rGO composite benefits from the introduction of graphene as a highly conductive, flexible, and large-surface-area scaffold to provide good electronic contact between active materials, suppress the aggregation of intermediate products, and alleviate the volume change during sodiation and desodiation. The encouraging experimental results suggest that the TiO2@rGO composite has great potential as a high-capacity and high-stability anode for the sodium-ion batteries.