Thermally Activated Multilayered Carbon Cloth as Flexible Supercapacitor Electrode Material with Significantly Enhanced Areal Energy Density

Carbon cloth, an inexpensive and conductive textile, holds great promise as substrate for constructing electrical double‐layer capacitors due to its mechanical and electrochemical superiority. However, its widespread application is significantly hampered by the intrinsic low specific capacity. In this work, we demonstrate that the areal capacitance of commercial carbon cloth is raised for 800‐folds by a direct thermal activation strategy. When evaluated as the symmetric supercapacitor electrodes, thermally activated carbon cloth (TACC) displays the outstanding performance with areal capacitance up to 3291 mF cm −2 and the energy density of 740 μW h cm −2 at a power density of 9000 μW cm −2 . In addition, the TACC‐based electrode reserves 95.2 % capacitance after 10,000 charge‐discharge cycles in a neutral NaBF 4 electrolyte, showing outstanding cycle durability of the material. This work offers a foolproof and scalable method to prepare flexible electrode materials for wearable energy storage devices.