Integrated FeOOH nanospindles with conductive polymer layer for high-performance supercapacitors

The development of efficient electrode materials with high energy density and high power density is crucial to the assembly of high-performance storage device. One-dimensional (1D) coaxial nanostructured materials with large surface area and superior ion transport have shown great potential for enhancement of electrochemical performance. In this paper, we design a class of 1D PPy-sheathed FeOOH nanospindles (FeOOH@PPy) as integrated electrode for supercapacitors (SCs). The 1D coaxial nanostructures and elaborate integrated conductive layer endow them with excellent electrochemical performance. For example, the as-obtained FeOOH@PPy electrode exhibits a specific capacitance of 1140 F g−1 at a current density of 1 A g−1, which is two folds larger than that of the bare FeOOH. Furthermore, the as-assembled FeOOH@PPy//AC asymmetric supercapacitor (ASC) reveals a high specific energy density of 39.1 Wh kg−1 with a power density of 800.0 W kg−1. After 5000 cycling tests, the device retains 78.7% of the initial specific capacitance, showing its good stability. The present work represents an important step toward rational fabrication of iron-based supercapacitor electrodes with new horizons for fundamental and technological applications.