Multidimensional structure of CoNi₂S₄ materials: structural regulation promoted electrochemical performance in a...

Multidimensional architectures of CoNi₂S₄ electrode materials are rationally designed by engineering the surface structure toward that of high-performance supercapacitors. The fabrication of a special morphology is highly dependent on the synergistic effect between the guidance of Co-Ni precursor arrays and a subsequent sulfidation process. The unparalleled CoNi₂S₄ electrode materials (NS-3) deliver a significantly enhanced specific capacitance (3784.6 F g^-1 at 3 A g^-1), accompanied by an extraordinary rate capability (2932.3 F g^-1 at 20 A g^-1) and excellent cycling life. The outstanding supercapacitor performance stated above stems from the advantages of a multidimensional structure generated by crosslinking 2D microsheets/1D nanowires/2D ultrathin nanosheets; this structure supplies additional efficient active sites and a large contact area at the electrode-electrolyte interface, providing faster transport kinetics for electrons and ions. For practical applications, asymmetric devices based on an NS-3 positive electrode and active carbon negative electrode exhibit a high energy density of 38.5 W h kg^-1 accompanied by a power density of 374.9 W kg^-1 (22 W h kg^-1 at 7615.4 W kg^-1). The above results indicate that the design of multidimensional Co-Ni-S materials is an effective strategy to achieve a high-performance supercapacitor.