Combining ionic liquid-based electrolytes and nanostructured anatase TiO2 anodes for intrinsically safer sodium-ion batteries

In an attempt to realize sodium-ion batteries with enhanced safety, we report herein the utilization of ionic liquid (IL)-based electrolytes for cycling nanoparticulate anatase TiO2 as sodium-ion anode material. The use of the IL-based electrolyte results in the highly stable cycling performance of anatase TiO2-based electrodes, providing an initial specific capacity of 159 mAh g−1 when applying a specific current of 33.5 mA g−1, and still 155 mAh g−1 after 80 full (dis-)charge cycles. Moreover, a very promising rate performance is obtained with specific capacities of 108 and 78 mAh g−1 for specific currents of 335 and 670 mA g−1, respectively. Indeed, the excellent electrochemical performance, and high coulombic efficiency, as well as the electrochemical impedance spectroscopy results indicate the highly beneficial impact of the IL-based electrolyte on the formation of a stabilized solid electrolyte interphase (SEI).