A family of MOFs@Wood-Derived hierarchical porous composites as freestanding thick electrodes of solid supercapacitors with enhanced areal capacitances and energy densities

A general strategy is developed to synthesize a family of metal-organic frameworks decorated on wood ([email protected], MOFs = ZIF-8, ZIF-67, MOF-74, or MOF-199) composite materials. The carbonized/activated [email protected] derived hierarchical porous composites ([email protected]) can be directly used as freestanding thick electrodes of solid symmetric supercapacitors (SSSCs) with enhanced areal capacitances and energy densities. This can be attributed to the combination of the three-dimensional (3D) porous network structure of natural wood and the microporous/mesoporous property of MOFs nanocrystals. Notably, the [email protected] electrode displays high areal specific capacitances of 12.52 and 8.95 F/cm2 at the current densities of 1 and 20 mA/cm2, respectively. Moreover, a SSSC assembled by two identical [email protected] electrodes delivers a superior energy density of 0.55 mWh/cm2 at a power density of 0.5 W/cm2, while maintaining 96.8% of initial capacitance over 10,000 cycles.