Electrochemical performance of Fe-Co bimetallic oxide composite as cathode for aqueous zinc-ion batteries

The development of aqueous zinc-ion batteries is constrained by issues such as capacity decay and sluggish reaction kinetics of cathode materials. This study fabricated a Co₃O₄@Fe₂O₃ composite on carbon cloth via a two-step hydrothermal method. XPS analysis reveals a 0.2 eV negative shift in the Co 2p binding energy, suggesting electronic interaction between Co₃O₄ and Fe₂O₃; SEM and TEM images demonstrate uniform distribution of Fe₂O₃ particles on Co₃O₄ nanowires, with EDS mapping confirming overlapping spatial distributions of Fe, Co, and O elements. The Co₃O₄@Fe₂O₃/CC composite achieves a reversible specific capacity of 164.9 mAh/g at 1 A/g, exceeding that of pure Co₃O₄/CC (129.4 mAh/g). After 100 cycles at 0.1 A/g, the composite retains 67.6% of its capacity, exceeding the 59% retention of Co₃O₄/CC. In rate performance tests, the composite exhibits 87.8% capacity retention when the current density increases from 0.1 to 1 A/g, significantly higher than the 72.7% of Co₃O₄/CC. EIS analysis indicates a reduced charge transfer resistance, confirming improved reaction kinetics. This work provides insights into the design of polymetallic oxide composite cathodes.