Carbon nanotube-based electrodes for flexible supercapacitors

Flexible supercapacitors (SCs) have attracted increasing attention as the power supply unit for portable/wearable electronics. Carbon nanotubes (CNTs) are promising candidate materials for flexible SC electrodes because of their outstanding mechanical property, high electrical conductivity, large surface area, and functionability. CNTs can assemble into various macroscopic materials with different dimensions. In this review, flexible CNT assemblies including 1D fibers, 2D films, and 3D aerogels and sponges are introduced with a focus on the design strategies and fabrication techniques. The recent developments and state-of-the-art applications of such structures as electrodes in flexible SCs are summarized based on device configurations including sandwiched, interdigital in-plane, and cable-type configurations. The flexible CNT-based electrodes have shown great advantages in bendability, stretchability and/or compressibility, as well as a long cycle lifetime. The current challenges and future research opportunities in this field are also discussed.