Architecture of Binder-Free Positrodes for Advance Supercapacitors: A Electrodeposited Battery-Type Ternary Cobalt–Nickel–Copper Sulfide

Abstract

With growing global energy demands, the development of efficient energy storage devices like hybrid supercapacitors (HSCs) has been recognized as a viable technology, owing to their superior energy storage performance. This work demonstrated the binder-free electrodeposition synthesis of ternary Co₉S₈/NiS₂/Cu₂S (CNCS) on Ni foam through cyclic voltammetry (CV) and chronoamperometry (CA) deposition modes for HSC applications. The electrochemical outcomes indicated that the CNCS electrode prepared via the CA mode exhibited enhanced electrochemical activity compared with the CV mode. Specifically, the CA-deposited CNCS electrode demonstrated a notable specific capacity of 460.15 C g^–1 at 1 A g^–1, remarkable rate capability, and low resistance. The charge storage mechanism being majorly influenced by the diffusive controlled redox reactions as determined from Dunn’s theoretical model confirmed the battery-type features of the CNCS deposited in the CA mode. For practical utility, an HSC device CNCS(+)||activated carbon(−) was constructed that displayed a high energy density of 86.71 Wh kg^–1 and a power density of 1134 W kg^–1. This device exhibited exceptional cycling stability and maintained a capacity retention of 95.4% over 5000 cycles. The promising electrochemical performance of the CA-deposited CNCS electrode was attributed to its uniform nanosheet structure, which facilitated redox reactions and offered increased active sites for charge storage. This investigation highlights the potential of binder-less electrodeposition fabrication of ternary metal sulfides on Ni foam as an efficient electrode material for the advancement of high-performance HSCs.