Highly stable supercapacitors with conducting polymer core-shell electrodes for energy storage applications

Conducting polymers such as polyaniline (PAni) show a great potential as pseudocapacitor materials for electrochemical energy storage applications. Yet, the cycling instability of PAni resulting from structural alteration is a major hurdle to its commercial application. Here, the development of nanostructured PAni-RuO2 core-shell arrays as electrodes for highly stable pseudocapacitors with excellent energy storage performance is reported. A thin layer of RuO2 grown by atomic layer deposition (ALD) on PAni nanofibers plays a crucial role in stabilizing the PAni pseudocapacitors and improving their energy density. The pseudocapacitors, which are based on optimized PAni-RuO2 core-shell nanostructured electrodes, exhibit very high specific capacitance (710 F g-1 at 5 mV s-1) and power density (42.2 kW kg-1) at an energy density of 10 Wh kg-1. Furthermore, they exhibit remarkable capacitance retention of ≈88% after 10 000 cycles at very high current density of 20 A g-1, superior to that of pristine PAni-based pseudocapacitors. This prominently enhanced electrochemical stability successfully demonstrates the buffering effect of ALD coating on PAni, which provides a new approach for the preparation of metal-oxide/conducting polymer hybrid electrodes with excellent electrochemical performance. Polyaniline RuO2 core-shell electrodes are fabricated by dilute chemical polymerization and atomic layer deposition. The RuO2 layer stabilizes the polyaniline pseudocapacitors and significantly improves their energy density. A specific capacitance of 710 F g-1 at 5 mV s-1 and power density of 42.2 kW kg-1 at an energy density of 10 Wh kg-1 are obtained. Capacitance retention of ≈88% after 10 000 cycles at 20 A g-1, is achieved.