A Self-supported Graphene/Carbon Nanotube Hollow Fiber for Integrated Energy Conversion and Storage

Wearable fiber-shaped integrated energy conversion and storage devices have attracted increasing attention, but it remains a big challenge to achieve a common fiber electrode for both energy conversion and storage with high performance. Here, we grow aligned carbon nanotubes (CNTs) array on continuous graphene (G) tube, and their seamlessly connected structure provides the obtained G/CNTs composite fiber with a unique self-supported hollow structure. Taking advantage of the hollow structure, other active materials (e.g., polyaniline, PANI) could be easily functionalized on both inner and outer surfaces of the tube, and the obtained G/CNTs/PANI composite hollow fibers achieve a high mass loading (90%) of PANI. The G/CNTs/PANI composite hollow fibers can not only be used for high-performance fiber-shaped supercapacitor with large specific capacitance of 472 mF cm(−2), but also can replace platinum wire to build fiber-shaped dye-sensitized solar cell (DSSC) with a high power conversion efficiency of 4.20%. As desired, the integrated device of DSSC and supercapacitor with the G/CNTs/PANI composite hollow fiber used as the common electrode exhibits a total power conversion and storage efficiency as high as 2.1%. Furthermore, the self-supported G/CNTs hollow fiber could be further functionalized with other active materials for building other flexible and wearable electronics. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40820-020-0390-x) contains supplementary material, which is available to authorized users.