Rational design of NiCo₂O₄@carbon hollow spheres as a high-performance electrode material for flexible supercapacitors

The design of innovative, flexible electrode materials with high electrochemical performance is critical for the development of next-generation supercapacitors. Here, we report the rational synthesis of NiCo₂O₄@carbon hollow spheres, engineered <i>via</i> a metal-organic framework (MOF)-templated strategy, as a high-performance electrode material for flexible supercapacitors. The unique hollow structure of NiCo₂O₄@carbon enhances ion accessibility and electron transport, while the carbon layer provides structural stability and conductivity, significantly boosting energy storage capabilities. Structural characterization confirms the well-defined hollow morphology and uniform carbon coating, optimizing electrochemical activity. Electrochemical analysis reveals outstanding capacitance, enhanced performance even at elevated current densities, and long-term stability, making NiCo₂O₄@carbon hollow spheres a promising candidate for flexible, energy-dense supercapacitors. The material achieves a high specific capacitance of 733 F g^-1 at 1 A g^-1, with minimal degradation over 5000 cycles, underscoring its potential in wearable electronics. This work highlights the effective use of MOF templates for creating hierarchical nanostructures, offering valuable insights into the rational design of flexible energy storage materials.