CoNi-MOF derived S-CN/NC/CNTs with tailored 3d network and active dispersion for quasi-solid-state supercapacitors

Three-dimensional S-CN/NC/CNTs network composites were synthesized via a combined hydrothermal and high-temperature treatment strategy. And their electrochemical behavior as supercapacitor electrodes was investigated. Compared with conventional synthesis routes, this method provides distinct advantages. Cobalt and nickel nanoparticles catalyze the directional growth of carbon nanotubes (CNTs) from melamine, forming a uniform coating structure that significantly enhances the electrical conductivity of the electrode. Concurrently, the sulfidation of cobalt and nickel nanoparticles dispersed within the nitrogen-doped carbon (NC) matrix and CNT network generates abundant redox-active sites, thereby improving the specific capacitance. Within this composite, Co-Ni-S functions as the electrochemically active phase, NC serves as the structural scaffold, and CNTs form an interconnected three-dimensional conductive framework that facilitates efficient electron transport. The synergistic interaction among these components endows the material with superior electrochemical performance. The optimized composite exhibits a high specific capacitance of 2104 F g⁻¹ at 0.5 A g⁻¹ in 6 M KOH electrolyte. Furthermore, a flexible quasi-solid-state supercapacitor assembled using this material as the positive electrode, activated carbon as the negative electrode, and a gel polymer electrolyte achieves an energy density of 40.3 Wh kg⁻¹ at a power density of 750 W kg⁻¹ , maintaining 87.6 % capacitance retention after 5000 cycles at 10 A g⁻¹ with excellent mechanical flexibility. This study presents an effective route for enhancing the electrochemical performance of three-dimensional composite electrodes through hierarchical conductive network design and controlled active-site dispersion, offering valuable insights for the development of high-performance energy storage materials.