Facile and Sustainable Synthesis of Co3O4@ Hollow-Carbon-Fiber for a Binder-Free Supercapacitor Electrode

The carbon fibers with hollow structure were prepared by carbonization of renewable and inexpensive cotton. The surface of hollow carbon fiber was further modified by Co3O4 nanoparticles via a simple impregnation method and subsequent calcination process. The prepared Co3O4@cotton-derived hollow carbon fibers (CHCFs) maintained the macroscopic morphology and flexibility of the cotton. As binder-free electrodes, Co3O4@ HCFs exhibited much better electrochemical behavior than that of pure Co3O4. Especially, Co3O4@ CHCF-2 showed a high specific capacitance of 566.89 F g(-1) at a current density of 1 A g(-1) and high capacitance retention of 69.38% at 15 A g(-1) in 6 M KOH aqueous electrolyte. Using Co3O4@CHCFs as positive electrode and cotton-based activated carbon (AC) as negative electrode, our asymmetric supercapacitor exhibited high energy density and excellent cycling stability. Moreover, this electrode material can be easily prepared on a large scale due to its sustainability, low cost, facile preparation and environmental friendliness.