Single Carbon Fibers with a Macroscopic‐Thickness, 3D Highly Porous Carbon Nanotube Coating

Macroscopic CNTs@CF hybrid fibers are fabricated by directly growing a millimeter‐thick 3D porous carbon nanotube sponge layer on a single carbon fiber with high interfacial strength, quantified by pull‐out tests, and show potential applications in reinforced nanocomposites and high‐performance fiber‐shaped energy devices such as supercapacitors and lithium‐ion batteries.