Stable metal-organic frameworks with Zr6 clusters for alkaline battery-supercapacitor devices

An alkaline-stable Zr-based material, PCN-777, has been elected and solvothermally prepared by reacting ZrOCl₂ with the tripodal linker 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoate (H₃TATB). This powder material exhibits an irregular octahedron motif, providing good stability and high-power density when it is employed as electrode material for supercapacitors (SCs). The results indicate that the specific capacity, under a three-electrode configuration, is 291.9 C g⁻¹ at a current density of 1.5 A g⁻¹ obtained from the chronopotentiometry charge-discharge test. Assembled into a two-electrode system with activated carbon (AC) negative, the corresponding battery-supercapacitor device denoted as PCN-777//AC delivers a specific capacitance of 48.72 F g⁻¹ at the constant current-density value of 0.5 A g⁻¹. Besides, this device delivered a maximum energy density of 17.3 Wh kg⁻¹ within the power-density value of 399 W kg⁻¹, an excellent alkaline-endurance life during 2000 unceasing cycles and practical applications in powering LEDs, suggesting the potential practicality under strong alkaline surroundings. Furthermore, the structural alteration before and after long-term cycling has also been investigated.