Freestanding polypyrrole/carbon nanotube electrodes with high mass loading for robust flexible supercapacitors

Abstract

To meet the increasing requirement of flexible energy storage devices, it is critical to develop an electrode with commercial-level mass loading of active material for supercapacitors. Herein, we fabricated a high mass loading and freestanding CNT@PPy electrode (6.07 mg cm⁻²) by a simple vacuum filtration and low-temperature polymerization method. Moreover, owing to the high conductivity of CNT fiber networks offering a fast electron transporting passage, the optimized CNT@PPy electrode exhibits a prominent areal capacitance (2.6 F cm⁻²) with significantly improved mechanical properties (its ultimate tensile strength is 20.7 MPa, 23 times higher than that of pure CNT film). The freestanding all-solid-state symmetric supercapacitor based on the optimized CNT@PPy electrode obtains a high power density of 0.64 mW cm⁻² at an energy density of 76.7 μW h cm⁻².