Paramecium-Like Iron Oxide Nanotubes as a Cost-Efficient Catalyst for Nonaqueous Lithium-Oxygen Batteries

Fe₂O₃-based catalysts have been developed to achieve a low overpotential and a long cycle life for nonaqueous Li–O₂ batteries. However, previous studies focus mainly on nanoparticles or nanoflakes, which have shown limited improvements for battery performance. Here, paramecium-like Fe₂O₃ nanotubes (FNTs) are synthesized by a hard-template method and applied as the catalyst in a nonaqueous Li–O₂ battery. The large specific surface area and unique tubular structure of the FNTs allow the nonaqueous Li–O₂ battery to deliver a high capacity of 6000 mAh g⁻¹ at a discharge current density of 500 mA g⁻¹ with a low discharge and charge overpotential of approximately 0.19 and 0.85 V, respectively. Moreover, the battery can be operated at a discharge current density as high as 1000 mA g⁻¹ with a capacity of 3940 mAh g⁻¹ and demonstrates an excellent rate capability. The prepared catalyst enables the battery to maintain the discharge capacity and Coulombic efficiency without any degradation for 150 cycles at 500 mA g⁻¹ with a fixed capacity of 500 mAh g⁻¹, which is 110 more cycles than the battery without the catalyst.