Restacking-free crumpled anatase TiO2 nanosheets synthesized by spray pyrolysis for high-performance Na-ion battery anodes

Abstract

Anatase TiO2 nanosheets have received considerable attention as high-power anodes for Na-ion batteries (SIBs) owing to their excellent electrochemical activities and ultrathin electron pathways in the out-of-plane direction. However, the large-scale synthesis of anatase TiO2 nanosheets remains challenging. Although the top-down approach of liquid-phase exfoliation is an established method for mass producing high-quality TiO2 nanosheets, it is difficult to prevent nanosheet restacking owing to electrostatic attraction that occurs during the conventional drying process. To overcome this inherent drawback, crumpled anatase TiO2 nanosheets were designed and synthesized without restacking and agglomeration by scalable spray pyrolysis, which effectively improved the rate performance of SIBs. Even without carbon coating, the anatase TiO2 nanosheet exhibited high reversible capacity (243.9 mA h g-1 at 0.1 mA g-1) and excellent long-term cycling stability (156.25 mA h g-1 after 10,000 cycles). Therefore, the developed synthesis strategy is suitable for the practical, large-scale production of nanosheets, which are promising anode materials for high-performance SIBs.