Comparative investigation of Fe₂O₃ and FeS₂ as cathode materials for rechargeable magnesium batteries

Rechargeable magnesium batteries have been considered as one of the promising candidates for replacing lithium-ion batteries due to their high energy and power densities. However, the development of rechargeable magnesium batteries has been sluggish, primarily due to the lack of cathode materials with high capacity and cycling stability. Cost-effective Fe₂O₃ and FeS₂ cathode materials were synthesized for rechargeable magnesium batteries using hydrothermal synthesis and solid-phase methods, respectively. Benefiting from the special structure of Fe₂O₃, a high reversible discharge capacity of 182.3 mAh g⁻¹ at 30 mA g⁻¹ can be provided. In contrast to Fe₂O₃, magnesium batteries with FeS₂ cathodes exhibit a low reversible discharge capacity of 103.7 mAh g⁻¹. The excellent energy storage performance of Fe₂O₃ is attributed to its unique structure, which effectively enhances the contact area between the electrolyte and cathode active material, thereby providing abundant reaction sites and reducing the magnesium ion migration barrier. This underscores the potential of Fe₂O₃ as a promising cathode material for advanced rechargeable magnesium batteries.