Balancing high performance with synthesis complexity: one-step hydrothermal growth of self-supported NiCo2Se4 nanoflowers on carbon cloth for advanced asymmetric supercapacitors

Abstract

Bimetallic transition-metal selenides are promising supercapacitor electrodes due to their high theoretical capacitance and rich redox activity. However, achieving high performance often relies on complex multi-step syntheses, limiting practical application. Herein, a simplified one-step hydrothermal strategy is employed to directly grow hierarchical NiCo₂Se₄ nanoflowers on flexible carbon cloth (CC). This in situ strategy eliminates binders and conductive additives, reduces interfacial resistance, and enhances structural integrity. The optimized NiCo₂Se₄/CC electrode delivers a competitive specific capacitance of 1479 F g⁻¹ (4.42 F cm⁻²)at 1 A g⁻¹, excellent rate capability (90.1% retention at 10 A g⁻¹), and stable cycling performance (84% retention after 5000 cycles). An asymmetric supercapacitor assembled with activated carbon achieves 30.39 Wh kg⁻¹ at 2549.9 W kg⁻¹ and maintains 87.6% capacitance after 20 000 cycles. Overall, this work shows that competitive electrochemical performance can be achieved through a streamlined one-step synthesis, offering a practical and scalable fabrication route without complex post-processing.