Polypyrrole-encapsulated Fe2O3 nanotube arrays on a carbon cloth support: Achieving synergistic effect for enhanced supercapacitor performance

It is highly attractive to design Fe 2 O 3 -based nanocomposite anodes for supercapacitors (SCs). Herein, polypyrrole-encapsulated Fe 2 O 3 nanotube arrays grown on carbon cloth (Fe 2 O 3 NTs@PPy/CC) were fabricated by combination of sacrificial template and electrodeposition methods. Such Fe 2 O 3 NTs@PPy/CC exhibits boosted pseudocapacitance and stability. In 1 M Na 2 SO 4 , it delivers a specific capacitance of 237 mF cm −2 at 1 mA cm −2 , and still retains 80% of initial capacity at 10 mA cm −2 even after 10,000 cycles. The theoretical calculation results reveal that PPy exhibits a strong adhesion on the surface of Fe 2 O 3 , and then effectively stabilizes the electrode structure. The interface between Fe 2 O 3 and PPy possesses more stable Na + storage sites to substantially enhance pseudocapacitance. The interactions of Fe 2 O 3 nanotube arrays and conductive polymers can simultaneously cause faster ion transfer, more surface charge storage, and higher structural stability for Fe 2 O 3 . The asymmetric aqueous supercapacitor devices consisted of Fe 2 O 3 NTs@PPy and MnO 2 electrodes with maximum operating potential of 2.0 V achieve a high areal energy density of 59.4 µWh cm −2 (24.2 Wh kg −1 ) at a power density of 1 mWh cm −2 (408.2 W kg −1 ) along with good stability. This work seeks a deeper insight for synergistic effect between PPy and Fe 2 O 3 , and offers a novel strategy to design the nanostructured composite with enhanced interface area for energy storage.