Mixed-Surfactant-Assisted Synthesis of Dual-Phase Li4Ti5O12-TiO2 Hierarchical Microspheres as High-Performance Anode Materials for Li-Ion Batteries

Graphical In the mix : A mixed-surfactant-assisted synthesis of dual-phase Li 4 Ti 5 O 12 -TiO 2 hierarchical microspheres is proposed. The ratio of anionic/cationic surfactant regulates the dual-phase ratio and primary structure morphology of the final product. The optimal sample obtained has a better electrochemical performance than similar state-of-the-art materials. A mixed-surfactant-assisted method was developed to synthesize dual-phase Li 4 Ti 5 O 12 -TiO 2 hierarchical microspheres. The ratio of anionic/cationic surfactant could regulate the primary structure morphology and the dual-phase ratio of the final product, in which the primary structure morphology could be stacked nanosheets, small nanoparticles, or large nanoparticles. The sample with a primary structure morphology of small nanoparticles had the highest specific surface area of 79.38 m 2 g −1 and the best electrochemical performance because of its high Li + migration rate, low polarization, and appropriate TiO 2 content. Its capacity reached 153.5 mA h g −1 at a current rate of 40 C, and it retained nearly 100 % of its capacity after 100 cycles. A self-assembly mechanism of the mixed surfactant was highlighted to explain the formation of hierarchical microspheres. The physical and electrochemical properties of obtained material were correlated effectively.