Honeycomb structured nano MOF for high-performance sodium-ion hybrid capacitor

Sodium-ion hybrid capacitors (SIHCs) combine the advantages of batteries and supercapacitors, which are considered promising energy storage devices due to their low cost and abundant reserves. Herein, we synthesize interconnected anode materials with Co-MOF-74 nanoparticles anchored and dispersed on 3D functionalization graphene oxide (FGO). The honeycomb structured crystal structures of pristine Co-MOF-74 are maintained well, which enables sufficient electrolyte diffusion and fast ion transfer. Furthermore, functional groups on FGO as active sites guarantee the uniform distribution and confined size of Co-MOF-74, thus leading to sufficient interface contact as well as high electron conductivity. As a result, the Co-MOF-74|FGO-180 electrode displays a reversible capacity of about 416 mA h g−1 at a current rate of 0.1 A g-1 after 100 cycles in the Na-ion half-cell. As constructed SIHC device with Co-MOF-74|FGO-180 anode and activated carbon (AC) cathode delivered high energy and power density of 240 Wh kg−1 and 10 kW kg−1 within 0–4.0 V. The good electrochemical performance of the electrode material provides a feasible method for developing high-performance anode materials for SIHCs.