Abstract: MgCo₂O₄，cobalt-based metal oxides with spinel-type，possesses ultra-high theoretical specific capacitance（3 122 F/g），becoming a hot topic for supercapacitors. To get high-capacitance MgCo₂O₄ electrode materials for supercapacitors，MgCo₂O₄ precursor on nickel foam was synthesized by hydrothermal route with different amounts of surfactant sodium dodecyl sulphate. Then MgCo₂O₄ nanowires were obtained through a lower temperature calcination process in this work. It showed that the surfactant sodium dodecyl sulphate affected not only the micromorphology of MgCo₂O₄ electrode material，but also its electrochemistry performance. When 1 mmol of surfactant sodium dodecyl sulphate was added ，the as-prepared MgCo₂O₄ nanowires exhibited a superior specific capacitance of 4 914 F/g at the current density of 1 mA/cm². After 1 000 cycles at the current density of 20 mA/cm²，53. 48% of initial capacitance was retained when it was used as a binder-free electrode material for supercapacitors. The asymmetric supercapacitor was assembled with MgCo₂O₄ nanowires and activated carbon respectively set as the positive and negative electrode，which exhibited 72. 59 F/g at the current density of 1 A/g，meanwhile，the energy density can reach 25. 8 Wh/kg at the power density of 920. 86 W/kg. Additionally，after 1 000 cycles of the asymmetric supercapacitor，the specific capacitance was maintained at 94. 77%，manifesting the great potential of MgCo₂O₄ as excellent material for energy storage.

Key words: MgCo₂O₄ nanowires, surfactant, specific capacitance, cycle performance, asymmetric supercapacitor