In situ reduction-sulfurized FeS₂ based on iron oxide as electrocatalyst for rechargeable Li-O₂ batteries

Significant advancements have been made in the development of lithium-oxygen batteries, achieving impressive results. However, their practical application is hindered by issues such as short cycle life, rapid capacity decay, and low energy conversion efficiency. Selecting suitable electrolytes and cathode catalysts can effectively address these challenges and enhance battery performance. This study investigates the use of Fe₂O₃ and FeS₂ as cathode catalysts for lithium-oxygen batteries. The structural characteristics and surface morphologies of the Fe₂O₃ and FeS₂ samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical performances of these catalysts were compared, showing that FeS₂ has a higher charge/discharge specific capacity (5740 mAh g⁻¹ at a current density of 100 mA g⁻¹) compared to Fe₂O₃ (2676 Ah g⁻¹ at the same current density). Furthermore, FeS₂ exhibited better cycling stability, maintaining 97 cycles at 100 mA g⁻¹ current density with a 500 mAh g⁻¹ specific capacity limit and demonstrating lower electrochemical impedance. Electrocatalytic oxygen reduction tests also revealed that FeS₂ exhibits higher oxygen reduction reaction (ORR) catalytic activity than Fe₂O₃. These results indicate that FeS₂ outperforms Fe₂O₃ as a cathode catalyst in lithium-oxygen batteries.