Conversion-type charge/discharge reaction observed with Fe2O3-modified reduced graphene oxide positive electrode for aluminum rechargeable batteries

Aluminum rechargeable batteries were prepared using commercially available iron oxide powder or reduced graphene oxide modified with iron oxide nanoparticles as positive electrode materials. The commercially available iron oxide powder was reversibly charged/discharged, but its capacity was very small, whitlow 15 mA h g⁻¹. The charge/discharge mechanism was investigated by using X-ray diffraction, and it was found that iron oxide was reduced to iron metal during discharge, indicating a conversion-type reaction. This is the first time that a conversion-type positive electrode material for aluminum rechargeable batteries has been constructed using iron oxide. By utilizing a sulfone base electrolyte, we have fabricated the aluminum rechargeable batteries using a conversion reaction with copper chloride. A similar effect is expected for iron oxide. The use of reduced graphene oxide modified with iron oxide nanoparticles as a positive electrode resulted in a significant increase to 100 mA h g⁻¹ in charge/discharge capacity, and the capacity retention after 100 cycles was about 60 %, showing good cycle characteristics for a rechargeable battery as a conversion-type electrode material.