Enhancing supercapacitor performance using nanosheet-covered nanotube structures CoS/NiS@CNTs with carbon nanotubes as conductive substrates.

Transition metal sulfides have broad application prospects as supercapacitor electrode materials. However, their poor structural stability and conductivity hinder improvements in their electrochemical performance. Therefore, the introduction of highly conductive carbon nanotubes (CNTs) as sulfide growth substrates is considered to improve the microstructure and electrochemical performance of electrode materials. In this study, a highly conductive CNT solution was sprayed onto a nickel foam current collector, and CoS/NiS was successfully constructed on a CNT conductive substrate using a combination of hydrothermal and electrochemical deposition methods, forming a unique nanosheet-covered nanotube structure CoS/NiS@CNTs. The addition of an appropriate concentration of CNTs can not only serve as a substrate for the growth of CoS/NiS, but also effectively maintain the overall nanosheet structure. Thus, the CoS/NiS@CNTs (2-CSNS@CNTs) have a stable structure and a wide range of electrochemical reaction sites, ensuring excellent conductivity and cycling stability. The electrode material 2-CSNS@CNTs exhibited a specific capacity of 1427.05 C g at 1 A g. Additionally, the asymmetric supercapacitor 2-CSNS@CNTs exhibited a high energy density of 53.76 W h kg at 800 W kg and a capacity retention rate of 68.5% at 10 A g after 1000 cycles.