Rationally Designed PPy-Coated Fe2O3 Nanoneedles Anchored on N-C Nanoflakes as a High-Performance Anode for Aqueous Supercapacitors

Flexible supercapacitors have emerged as pivotal energy storage components in wearable smart electronic systems, owing to their exceptional electrochemical performance. However, the widespread application of flexible supercapacitors in smart electronic devices is significantly hindered by the developmental bottleneck of high-performance anode materials. In this study, a novel electrode composed of surface-modified Fe2O3 nanoneedles uniformly coated with a polypyrrole (PPy) film and anchored on Co-MOF-derived N-C nanoflake arrays (PPy/Fe2O3/N-C) is designed. This composite electrode, grown in situ on carbon cloth (CC), demonstrated outstanding specific capacity, rate performance, and mechanical flexibility, attributed to its unique hierarchical 3D arrayed structure and the protective PPy layer. The fabricated PPy/Fe2O3/N-C@CC (P-FONC) composite electrode exhibited an excellent specific capacitance of 356.6 mF cm−2 (143 F g−1) at a current density of 2 mA cm−2. The current density increased to 20 mA cm−2, and the composite electrode material preserved a specific capacitance of 278 mF cm−2 (112 F g−1). Furthermore, the assembled quasi-solid-state Mn/Fe asymmetric supercapacitor, configured with P-FONC as the negative electrode and MnO2/N-C@CC as the positive electrode, demonstrated robust chemical stability and notable mechanical flexibility. This study sheds fresh light on the creation of three-dimensional composite electrode materials for highly efficient, flexible energy storage systems.