Porous Cobalt Metal-Organic Frameworks as Active Elements in Battery-Supercapacitor Hybrid Devices.

With the trigonal linker 4,4',4″-s-triazine-2,4,6-triyltribenzoic acid as a building block, porous cobalt metal-organic frameworks (named as PCN) have been successfully prepared and directly utilized as active materials in alkaline battery-type devices. For comparison, their carbon-supported hybrids (CNFs/PCN) have also been employed as battery-type electrodes. We found that the pristine PCN displayed a better performance than the CNFs/PCN composite electrode in electrochemical cells. To further investigate their electrochemical performances, alkaline battery-supercapacitor hybrid (BSH) devices with these materials as positive electrodes and activated carbon (AC) as the negative electrode were fabricated. The results indicate that the PCN//AC BSH devices delivered a maximum energy density of 16.0 Wh kg-1 at a power density of 749 W kg-1 within the voltage range of 0-1.5 V, which are much higher than those of CNFs/PCN//AC devices (12.4 Wh kg-1 at 753 W kg-1).