NiCo-MOFs derived carbon matrix composites: A promising electrode construction for high-performance supercapacitors

Metal-organic frameworks (MOFs) are great precursors and templates for preparing adsorbents, catalysts and electrodes due to the porous structure and high specific surface area. We report a promising approach to prepare nanocrystalline Co, Ni sulfides embedded and N self-doped porous carbon (NPC) matrix composites derived from NiCo-MOFs. The CNS@NPC composite was used as electrodes for hybrid supercapacitors (HSCs). The as-prepared electrode achieved specific capacitance of 2,789 F g-1 at 1 A g-1, and high capacitance retention of 88.93% after 6,000 galvanostatic charge-discharge (GCD) cycles under 10 A g-1. The HSC structured with CNS@NPC//AC achieved an energy density of 46.79 Wh kg-1 at power density of 800 W kg-1. Meanwhile, specific capacitance of 131.56 F g-1 at 1 A g-1 and capacitance retention of 99.17% over 6,000 GCD cycles under 3 A g-1 were obtained. Space confinement by the carbon skeleton effectively prevents the aggregation of the redox active nanocrystalline and improves the durability of the electrode. Meanwhile, the carbon skeleton provides abundant charge transfer channels to enhance the redox reaction. In other words, synergistic effect of the carbon skeleton and the active redox nanocrystalline significantly improves the electrochemical properties of the composite.