Cation-Assisted Formation of Porous TiO2-x Nanoboxes with High Grain Boundary Density as Efficient Electrocatalysts for Lithium-Oxygen Batteries

Despite the ultrahigh energy density of rechargeable lithium oxygen (Li-O-2) batteries, their practical use is still hindered by the poor performance of electrocatalysts. Recently, porous and hollow nanostructured catalysts have been found to be promising electrocatalysts toward the ORR/OER to improve the performance of Li-O-2 batteries. However, the catalytic activities of the catalysts are still insufficient and the nanopores are easily clogged by the insoluble discharge products. Herein, highly porous and hollow TiO2-x nanoboxes (TiO2-x NBs) with large surface areas, increased oxygen vacancies, and high grain boundary density have been developed as an electrocatalyst for Li-O-2 batteries via a cation-assisted synthetic approach. The Li-O-2 batteries with TiO2-x NBs as the electrocatalyst exhibit a high specific capacity of 8569 mA h g(-1), excellent rate capability, and long cycle life up to 200 cycles when the capacity is limited to 1000 mA h g(-1). Moreover, this cation-assisted approach for fine-tuning the nanostructure could be an innovative strategy to design efficient electrocatalysts for high-performance Li-O-2 batteries.