Influence of different N‑benzoyl derivatives of isoleucine on electrochemical properties and pseudocapacitance performance of conductive polymer electroactive film: Electrochemical and theoretical study

Hierarchical NiCo2S4@NiCoP core-shell nanocolumn arrays on nickel foam as a binder-free supercapacitor electrode with enhanced electrochemical performance

A novel hierarchical core-shell nanocolumn array, with NiCo₂S₄ hollow nanowire (NiCo₂S₄ H-NW) as the core and NiCoP nanosheet (NiCoP NS) as the shell, has been directly synthesized on nickel foam (NF) as self-supported, binder-free electrode for high-performance supercapacitors. The morphological characterizations reveal that the diameter of NiCo₂S₄ H-NW core is ∼100 nm and the diameter of single NiCo₂S₄@NiCoP core-shell nanocolumn is ∼250 nm. Through a series of electrochemical tests and the analysis of charge storage kinetics, hierarchical NiCo₂S₄@NiCoP/NF electrode presents high areal specific capacitance of 5.98 F/cm² at 1 mA/cm², outstanding rate capability (70.29% capacitance retention with the current density increased from 1 to 50 mA/cm²) and superior cycling stability (92.94% of original capacity is retained after 5000 cycles at 10 mA/cm²). The prominent performance of NiCo₂S₄@NiCoP/NF electrode could be resulted from their unique hierarchical core-shell nanocolumn structure, which could offer abundant active sites near the interface for fast electrochemical reaction, and validly avoid the collapse of internal structure for the stability of whole structure in the repeated electrochemical measurement. The novel NiCo₂S₄@NiCoP/NF electrode offers a new method for future electrochemical energy storage devices with high-stability.