Hierarchical self-supporting sugar gourd-shape MOF-derived NiCo2O4 hollow nanocages@SiC nanowires for high-performance flexible hybrid supercapacitors.

Rational construction of hierarchical electrode materials has been a research hotspot in the field of energy storage. In this work, metal-organic framework (MOF) derived hollow NiCo2O4 nanocages (NCs) were strung by interwoven SiC nanowires (NWs) network on carbon cloth (CC), forming a unique sugar gourd-like core-shell architecture, which were fabricated via a multi-step process containing of chemical vapor deposition, solution reaction of MOF templates, ion exchanging/etching and subsequent heat treatment. Benefiting from the unique structural advantages, such as hierarchical porous structure with abundant active sites for electrochemical reactions and interwoven conductive networks for electron transport, the formed core-shelled CC/SiCNWs@NiCo2O4NCs as a binder supercapacitor electrode exhibits excellent electrochemical performance with a large specific capacitance (1377.6F g-1 at a current density of 1 A g-1), good rate capability (68.8% capacitance retention at 20 A g-1) and excellent cycling stability (88.3% capacitance retention after 6000 cycles). Furthermore, the hybrid supercapacitor based on CC/SiCNWs@NiCo2O4NCs and activated carbon, not only delivers a high energy density of 46.58 Wh kg-1 at the power density of 800 W kg-1, but also possesses good flexibility with high capacitance retention, exhibiting the application potential in the field of flexible energy storage. More importantly, our work gives a new thinking for structural design of SiCNWs-based and MOF-based electrode materials for high-performance flexible energy storage.