Synergetic surface coating and S-rich vacancy reconstruction NiCo2S4 electrode materials for high cycle stability asymmetric supercapacitor applications

Supercapacitors have emerged as a hot subject for new energy storage devices aiming to meet the essential energy demand for economic development. However, electrode materials have hindered the construction of high-energy density devices due to insufficient active sites, unfavorable electrical conductivity, and poor cycling stability, making their widespread practical application challenging. In this paper, nitrogen-doped carbon (NC)-coated S-rich vacancy NiCo2S4 nanoarrays (NCSx@NC-5/CC) and MoO3-x (MoO3-x-0.03/CC) possessing a heterojunction structure were constructed on carbon cloth as positive and negative electrode materials, respectively. Benefiting from the advantages of unique nanoarray structure, heterojunction structure, and the synergistic optimization of surface coating and S-rich vacancy reconstruction NiCo2S4 positive and MoO3-x negative electrode materials, the high-performance quasi-solid-state asymmetric supercapacitor was matched and assembled. This device exhibited a high specific energy of 38.41 Wh·kg−1 at a power density of 812.22 W·kg−1, and possessed 91.22 % cycling performance after 5000 cycles at a high current density of 5 A·g−1, given the power to red LED light-emitting diode for more than 30 min, demonstrating the superior energy storage performance of this kind of reconstruction of electrode materials.