Nitrogen‐Doped Hollow Carbonized Cotton Fully Covered with Trumpet‐Like Nanocarbons for High‐Performance Supercapacitors

Abstract Carbon materials obtained by carbonizing low‐cost natural materials tend to achieve a nearly solid original structure with a smaller specific surface area (SSA), which limits their application in electrochemical energy storage. In this work, by precisely controlling the heating rate and gas flow in the carbonization process, we successfully fabricated hollow carbonized cotton fibers fully covered with trumpet‐like nanocarbons (HCC@TNC) and the nitrogen‐doped product (N−HCC@TNC). N−HCC@TNC achieves a high SSA of 1477 m 2 g −1 and specific capacitance of 381 F g −1 at a current density of 2 A g −1 . Even at 400 A g −1 , N−HCC@TNC still retains 77 % of the capacitance at 2 A g −1 . Our approach to the hollow carbon fibers with surface trumpet‐like nanocarbons might provide a new way for carbonizing natural materials and low‐cost, high‐performance energy storage devices.