Construction of CoNi2S4 nanoarray electrode with high mass-loading via a differentiated deposition strategy for hybrid supercapacitor

The rational design of self-supporting electrodes with high mass loading and optimized morphology is essential for achieving high-performance sulfide-based energy storage systems. Thiospinel sulfides, owing to their unique bimetallic synergistic effects and superior electrical conductivity, represent promising candidates for advanced supercapacitor electrode materials. However, the precise control of hierarchical architectures at high mass loading remains challenging due to the limited solubility and distinct precipitation behaviors of various metal cations within thiospinel sulfides. To address the aforementioned challenges, a novel differential deposition strategy was employed to synthesize NiCo-based sulfide nanorod arrays with both high mass loading and diverse hierarchical structures in this work. Specifically, an open-porous CoNi 2 S 4 nanosheet arrays was first deposited on carbon cloth (CC) via ethanol/thioacetamide-assisted solvothermal synthesis. Subsequently, hydrothermal deposition facilitated epitaxial growth of CoNi 2 S 4 nanorods with minimized lattice mismatch, thereby strengthening bimetallic interactions. The as-obtained CoNi 2 S 4 nanorod arrays (6.61 mg cm −2 ) on carbon cloth exhibits an exceptional areal capacity of 5.12C cm −2 at 5 mA cm −2 and gravimetric capacity of 711C g −1 at 1 A g −1 , with good rate performance. Furthermore, the assembled CoNi 2 S 4 -EW//AC hybrid supercapacitor (HSC) shows a high areal capacitance of 1.41 F cm −2 at 5 mA cm −2 , an energy density of 0.64 mWh cm −2 at 9 mW cm −2 , and outstanding long-term cycling stability (retaining 84.6 % of its capacitance after 20,000 cycles). This work proposes a universal deposition strategy for the practical design and regulation of NiCo sulfide electrodes at high mass loading levels.