Interfacial construction between reduced graphene oxide and iron oxide induced high electrochemical performance for flexible battery

Fiber-shaped Ni/Fe batteries with high safety, cheap cost, and environmental friendliness have a wide range of applications in wearable and portable devices. However, their development is limited by the sluggish kinetics of the Fe-based anode. Herein, a well-designed fibrous Fe-based anode containing reduced graphene oxide (rGO) and Fe2O3 was constructed by a one-step co-electrodeposition strategy. Theoretical investigations reveal the improved carrier density as a result of the effective electrostatic interaction between rGO and Fe2O3. This interconnected heterostructure builds a bridge for electron transfer and ion diffusion, significantly accelerating the electrochemical reaction kinetics. The as-prepared rGO/Fe2O3 anode delivers an extraordinary volumetric capacity of 40.1 mAh cm-3 along with excellent rate capacity and cyclic stability. After coupling with the NiCoO cathode, the fabricated fibrous quasi-solid-state Ni/Fe battery shows the maximum volumetric energy density and power density of 19.9 mWh cm-3 and 961.6 mW cm-3. Moreover, this fibrous Ni/Fe battery confirms good capacity retention of 82.3% after 10,000 cycles and noteworthy mechanical flexibility. These results suggest a new prospect to design and construct highly efficient Fe-based anodic materials for energy storage.