Temperature-Dependent Morphologies of Precursors:\nMetalâOrganic Framework-Derived Porous Carbon for High-Performance\nElectrochemical Double-Layer Capacitors

Abstract

In\nthis work, three Cu metal–organic framework samples with\ntunable rhombic, squama, and trucated bipyramid morphologies have\nbeen synthesized at 0, 25, and 60 °C, respectively, and further\nemployed as precursors to initially prepare Cu@C composites by the\ncalcination–thermolysis procedure. Then Cu@C composites have\nbeen etched with HCl and subsequently activated with KOH to obtain\nactivated porous carbon (<b>APC-0</b>, <b>-25</b>, and <b>-60</b>). Interestingly, <b>APC-25</b> presents a loose\nmultilevel morphology of cabbage and possesses the largest specific\nsurface area (1880.4 m² g^–1) and pore\nvolume (0.81 cm³ g^–1) among these APC\nmaterials. Consequently, <b>APC-25</b> also exhibits the highest\nspecific capacitance of 196 F g^–1 at 0.5 A g^–1, and the corresponding symmetric supercapacitor cell\n(SSC) achieves a remarkable energy density of 11.8 Wh kg^–1 at a power density of 350 W kg^–1. Furthermore, <b>APC-25</b> shows excellent cycling stability, and the loss of\ncapacitance is only 7.7% even after 10000 cycles at 1 A g^–1. Significantly, five light-emitting diodes can be lit by six SSCs,\nwhich proves that <b>APC-25</b> can be used in energy storage\ndevices.