Self-supporting hierarchical porous NiCo2S4/RGO/CNTs nanohybrids with abundant exposed electroactive redox sites for excellent hybrid supercapacitor

Bimetallic sulfide NiCo ₂S ₄ is a highly promising electrode material for applications in novel sustainable high-performance energy storage devices, but its poor rate capability and cycling life need to be enhanced. Herein, we report a novel self-supporting hierarchical porous NiCo ₂S ₄ /RGO/CNTs nanohybrids (NCSRCs) by co-modification of NiCo ₂S ₄ nanoparticles with RGO and CNTs. The synergistic effect of RGO and CNTs not only constructs a hierarchical porous conductive network that facilitates charge transport kinetic and ion diffusion kinetic, but also provides abundant induced sites for the dispersion anchoring of NiCo ₂S ₄ nanoparticles due to their high specific surface area with rich functional groups, which reduces the stacking of NiCo ₂S ₄ nanoparticles and provides abundant exposed electroactive redox sites. Therefore, the electrochemical performance test results demonstrate that the NCSRCs electrodes exhibit significantly enhanced charge storage performance, showing a high specific capacity of 257.1 mAh g ⁻¹ at 0.3 A g ⁻¹ and good rate capability. In addition, the optimal NCSRC-24//N-RGO aqueous hybrid supercapacitor delivered a high specific energy of 33.67 Wh kg ⁻¹ and ultra-long durability with 82.44% capacity retention after 22,000 cycles. These results provide a facile approach to design and synthesize novel NCSRCs nanohybrids with superior properties for high-safety, sustainable and efficient aqueous energy storage devices.