Asymmetric Supercapacitor Based on Chemically Coupled Hybrid Material of Fe₂O₃‐Fe₃O₄ Heterostructure and Nitrogen‐Doped Reduced Graphene Oxide

Abstract

The synthesis of a novel chemically coupled hybrid material based on Fe2O3‐Fe3O4 heterostructure and nitrogen‐doped reduced graphene oxide (N‐rGO) for the development of high performance supercapacitor devices is demonstrated. The chemically coupled hybrid material is synthesized in a one‐pot method under hydrothermal condition, resulting in the formation of crystalline α‐Fe2O3 and poorly crystalline/amorphous Fe3O4. The Fe2O3‐Fe3O4 particles have an average size of 30–50 nm. Chemical integration of Fe2O3‐Fe3O4 with N‐rGO through Fe‐O−C bonds is achieved. The chemical coupling of N‐rGO with pseudocapacitive Fe2O3‐Fe3O4 enhances the overall performance of the composite. Two asymmetric supercapacitor devices using the hybrid material either as positive or negative electrode are fabricated. The supercapacitive behaviour is evaluated in terms of specific capacitance, energy density, power density and cycling stability, showing excellent performance. The asymmetric device based on hybrid material as the positive and activated carbon as the negative electrode, delivers a specific capacitance of 111.95 F g−1 at 0.8 A g−1 with an energy density of 44.93 Wh kg−1. The supercapacitor has excellent cycling stability with a capacitance retention of >92 % even after 10000 extensive charge‐discharge cycles. The all‐solid‐state asymmetric supercapacitor device is fabricated using gel electrolyte. Solid‐state devices connected in series successfully light up 29 LEDs.

Anode Electrodeposition of Fe/Fe3O4 composite on Carbon Fabric as a Negative Electrode for Flexible Ni−Fe Batteries

“…[19] The relevant weak satellite peaks appear at 719.3 and 733.5 eV attributed to Fe 2p 3/2 and Fe 2p 1/2 of Fe 3 + , respectively. [18] It is worth noting that there exists a weak peak centered at 706.5 eV, which is the reflection of Fe 0 , and it has been proved by previous reports. [20] The chemical state of metallic Fe 0 could arise from the reduction of slight amount of Fe 2 + and Fe 3 + of initial Fe oxides (such as FeOOH and Fe 3 O 4 ) by carbon thermal reduction reactions during the annealing process.…”

“…As shown in Figure 2(c), two obvious binding energies centered at 725.1 eV and 711.6 eV are exactly corresponding to Fe 2p 1/2 and Fe 2p 3/2 , respectively. [18] The peaks of Fe 2p 1/2 and Fe 2p 3/2 can be further deconvolved into several ones. Thereinto, the peaks at 710.7 and 724.1 eV are assigned to the featured peaks for Fe 2 + , while the peak appearing at 712.2 and 725.7 eV represents the binding energy of lattice Fe 3 + .…”

Nanoporous Iron Oxide/Carbon Composites through In-Situ Deposition of Prussian Blue Nanoparticles on Graphene Oxide Nanosheets and Subsequent Thermal Treatment for Supercapacitor Applications

“…0.3 V and a reduction peak at ca. −0.7 V vs. Ag/AgCl, [29] for the iron oxide/carbon composite electrode implies reversible redox reactions of iron ion [30].…”

True Meaning of Pseudocapacitors and Their Performance Metrics: Asymmetric versus Hybrid Supercapacitors

“…Table 1 summarizes the electrochemical performance of ASSCs based on different negative‐electrodes with their corresponding gel electrolytes. [ 159–174 ]…”