To meet the development for smaller and faster electronic facilities in modern optoelectronics and electronics, it is critically important to discover matchable energy storage devices such as electrochemical capacitors, although the conventional planar structure cannot satisfy the pushing requirements.[1] The old textile technology may shed great light on achieving the goal. If the electrochemical capacitors are made in a wire or fiber format, they can be lightweight and flexible, and may be also easily integrated or woven into various electronic devices with low cost and high efficiency. To this end, it is a key to discover appropriate fiber electrodes that require combined excellent properties of being flexible, mechanical strong, electrically conductive, and thermally stable.

Owing to the remarkable chemical and physical properties, carbon nanomaterials have been widely studied for electrode materials in energy storage.[2–4] Among them, carbon nanotubes (CNTs) and ordered mesoporous carbon (OMC) represent two of the most explored systems.[5-8] CNT electrodes are generally prepared through an easy solution process.[9–12] The unique one-dimensional structure with high electrical conductivity favors the rapid charge separation and transport.[6] However, the used CNTs are mainly randomly dispersed, and the charges have to cross a lot of boundaries among them with low efficiencies.[13–15] In addition, the efficient surface area that is accessible to the electrolyte solution needs to be further improved.[14] By contrast, the OMC can be synthesized with both tunable pore structures and sizes that allow a high surface area for high specific capacitance.[7, 16–18] However, the OMC has typically shown a low electrical conductivity at macroscopic scale as the ordered structure generally appears in local regions at nanometer or micrometer scale.[14, 18, 19] Although either CNT or OMC materials have been investigated, no reports are available to combine their advantages in a composite format. In this Communication, a novel multi-walled carbon nanotube (MWCNT)/OMC composite fiber is developed with the skeleton MWCNTs being highly aligned along the axial direction and OMC being interconnected among the aligned MWCNTs. Compared with the conventional network structure, the alignment of MWCNTs favors a rapid charge separation and transport.[13–15] In addition, the high surface area of