Cation substitution for enhanced pseudocapacitance performance of spinel bimetallic sulfides porous nanowires for increased energy storage

Abstract

The utilization of cation substitution presents a prospective approach to manipulate the structural characteristics and enhance the electrochemical functionality of spinel cobaltous sulfide (Co₃S₄). However, the underlying mechanism behind the impact of distinct cation substitutions on this phenomenon remains inadequately elucidated. In this study, we perform a thorough assessment to elucidate the influence of replacing cations on the pseudocapacitive properties of porous nanowires made of spinel bimetallic sulfide (Me_xCo_3-xS₄; Me=Mn, Ni, Cu, and Co). One of the top competitors, NiCo₂S₄, demonstrates a significant specific capacitance of 1032.7 F g⁻¹ at a current density of 2 A g⁻¹. Furthermore, it demonstrates an impressive capacitance retention rate of 92.1% after undergoing 8000 cycles. Moreover, the use of NiCo₂S₄ and AC as the anode and cathode in the hybrid supercapacitor (HSC) lead to a significant energy density of 49.3 Wh kg⁻¹ at 1600 W kg⁻¹, validating the effectiveness of the prepared porous nanowire-like NiCo₂S₄ as an appropriate substance for energy storage systems. Density functional theory (DFT) confirms that the substitution of cation can stimulate the electrochemical activity of Co, facilitate stronger inter-element interactions, and synergistically enhance the conductivity of cobalt-based bimetallic sulfides.

Graphical abstract

The regulatory mechanism of cation substitution on the pseudocapacitance performance of Me_xCo_3-xS₄ is elucidated through the integration of DFT calculations and electrochemical analysis.