General Formation of M_xCo_3-xS₄ (M=Ni, Mn, Zn) Hollow Tubular Structures for Hybrid Supercapacitors

A simple and versatile method for general synthesis of uniform one-dimensional (1D) M_xCo_3-xS₄ (M=Ni, Mn, Zn) hollow tubular structures (HTSs), using soft polymeric nanofibers as a template, is described. Fibrous core-shell polymer@M-Co acetate hydroxide precursors with a controllable molar ratio of M/Co are first prepared, followed by a sulfidation process to obtain core-shell polymer@M_xCo_3-xS₄ composite nanofibers. The as-made M_xCo_3-xS₄ HTSs have a high surface area and exhibit exceptional electrochemical performance as electrode materials for hybrid supercapacitors. For example, the MnCo₂S₄ HTS electrode can deliver specific capacitance of 1094 Fg^-1 at 10 Ag^-1, and the cycling stability is remarkable, with only about 6% loss over 20000 cycles.