Polyaniline-Coated 3D Carbon Network Hybrid Structure Grown on Graphite Paper for an Ultralightweight and Ultrathin Wearable Supercapacitor

A flexible supercapacitor serves as an important energy storage component for fast electricity storage/release in the power module for next-generation wearable electronics. However, a major challenge still remains in realizing high volumetric and gravimetric energy storage performance densities in a flexible supercapacitor at the device level (including the electrodes and electrolyte). Herein, a polyaniline-coated 3D carbon network hybrid structure is in-situ grown on the surface of graphite paper (CNW@PANI/GP) as an electrode material for a flexible supercapacitor. A GP substrate provides high conductivity, low mass density, and ultrathin thickness. CNW@PANI offers high surface area and a good combination of electric double layer capacitive and pseudocapacitive behaviors. The in-situ growth offers interfacial covalent bonding for low interfacial resistance and good mechanical stability. Owing to these advantages, the CNW@PANI/GP-based flexible supercapacitor simultaneously possesses high energy storage performances, ultralight weight, and ultrathin thickness. High volumetric and gravimetric capacitances (19.8 F cm −3 /22.4 F g −1 ), energy densities, and power densities (1.76 mWh cm −3 and 459 mW cm −3 /1.99 Wh kg −1 and 517.5 W kg −1 ) are thus obtained in the quasi-solid-state supercapacitor based on the entire device, which surpasses most of the reported flexible supercapacitor devices. Moreover, the supercapacitor shows good flexibility and energy storage performance stability under mechanical deformations. The application of tandem supercapacitor devices for wearable self-powered electronics has been demonstrated. The findings in this work provide a high-performance and cost-effective electrode material for flexible energy storage in wearable electronic applications.