MnCo2O4/Ni3S4 nanocomposite for hybrid supercapacitor with superior energy density and long-term cycling stability

MnCo 2 O 4 is regarded as a good electrode material for supercapacitor due to its high specific capacity and good structural stability . However, its poor electrical conductivity limits its wide-range applications. To solve this issue, we integrated the MnCo 2 O 4 with Ni 3 S 4 , which has a good electrical conductivity, and synthesized a MnCo 2 O 4 /Ni 3 S 4 nanocomposite using a two-step hydrothermal process. Comparing with individual MnCo 2 O 4 and Ni 3 S 4 , the MnCo 2 O 4 /Ni 3 S 4 nanocomposite showed a higher specific capacity and a better cycling stability as the electrode for the supercapacitor. The specific capacity value of the MnCo 2 O 4 /Ni 3 S 4 electrode was 904.7 C g −1 at 1 A g −1 with a potential window of 0–0.55 V. A hybrid supercapacitor (HSC), assembled using MnCo 2 O 4 /Ni 3 S 4 and active carbon as the cathode and anode, respectively, showed a capacitance of 116.4 F g −1 at 1 A g −1 , and a high energy density of 50.7 Wh kg −1 at 405.8 W kg −1 . Long-term electrochemical stability tests showed an obvious increase of the HSC’s capacitance after 5500 charge/discharge cycles, reached a maximum value of ∼162.7% of its initial value after 25,000 cycles, and then remained a stable value up to 64,000 cycles. Simultaneously, its energy density was increased to 54.2 Wh kg −1 at 380.3 W kg −1 after 64,000 cycles.