NiCo₂O₄ nanosheets sheathed SiC@CNTs core-shell nanowires for high-performance flexible hybrid supercapacitors

Electrode materials with hierarchical self-supporting core–shell structures, with the metric of structural advantages and synergetic effect for different components, have been widely applied in supercapacitor. Besides, interface designing would improve the bonding of different components and further enhance the stability of electrochemical performance. In this work, by the introduction of CNTs layer to construct the conductive and rugged interface on SiC nanowires (NWs), the formed core–shell SiC_NWs@CNTs network were served as conductive skeleton for supporting NiCo₂O₄ nanosheets (NSs). Benefiting from the unique hierarchical structure with designed interface, the formed SiC_NWs@CNTs@NiCo₂O_4NSs electrode exhibits exceptional electrochemical performance with high specific capacitance of 2302F g⁻¹ (319.7 mAh g⁻¹) at 1 A g⁻¹, excellent rate capability (86.3% capacitance retention at 20 A g⁻¹) and outstanding cycling stability (95% capacitance retention after 5000 cycles). Furthermore, the hybrid supercapacitor assembled SiC_NWs@CNTs@NiCo₂O_4NSs and activated carbon (AC), exhibits a high energy density of 64.2 Wh kg⁻¹ at a power density of 0.79 kW kg⁻¹, long cycle life and good flexibility. More impressively, this work provides a facile method for rationally constructing electrode materials with hierarchical structures for high-performance flexible energy storage devices.