Zephyranthes-like Co₂NiSe₄ arrays grown on 3D porous carbon frame-work as electrodes for advanced supercapacitors and sodium-ion batteries

Developing suitable electrode materials for electrochemical energy storage devices by biomorph assisted design has become a fascinating topic due to the fantastic properties derived from bio-architectures. Herein, zephyranthes-like Co₂NiSe₄ arrays grown on butterfly wings derived three-dimensional (3D) carbon framework (Z-Co₂NiSe₄/BWC) is fabricated via hydrothermal assembly and further conversion method. Benefiting from its unique structure and multi-components, the obtained Z-Co₂NiSe₄/BWC electrode for supercapacitor delivers an excellent specific capacitance of 2, 280 F·g⁻¹ at 1 A·g⁻¹. Impressively, the constructed asymmetric supercapacitor using Co₂NiSe₄/BWC as positive electrode and activated butterfly wings carbon as negative electrode acquires a high energy density of 42.9 Wh·kg⁻¹ at a power density of 800 W·kg⁻¹ with robust stability of 94.6% capacitance retention at 10 A·g⁻¹ after 5, 000 cycles. Moreover, the Z-Co₂NiSe₄/BWC as anode for sodium-ion batteries exhibits a high specific capacity of 568 mAh·g⁻¹ at 0.1 A·g⁻¹ and high cycling stability (maintaining 80.1% of the second cycle after 100 cycles). The outstanding electrochemical performances are ascribed to that the synergistic effect of bimetallic selenides and N-doped carbon improves electrochemical activities and conductivity. One-dimensional (1D) nanoneedles grown on 3D porous framework increase the exposure of redox-active sites, endow adequate transmission channels of electrons/ions, and guarantee stability of the electrode during charge/discharge processes. This study will shed light on the avenue towards extending such nanohybrids to excellent energy storage applications.