Porous Fe3O4/C nanoaggregates by the carbon polyhedrons as templates derived from metal organic framework as battery-type materials for supercapacitors

The porous Fe 3 O 4 nanoaggregates were fabricated by the carbon polyhedron as templates through the hydrothermal method . The carbon polyhedron was obtained by the carbonization of ZIF-67 and subsequent acid treatment. The finial porous Fe 3 O 4 nanoaggregates possess high specific area of 547.5 m 2  g −1 with pore volume of 0.375 cm 3  g −1 . Such unique structures facilitate electrode materials fully exposed to electrolyte solution and maintain the structural stability during fast electrochemical reaction processes. Thereby, porous Fe 3 O 4 nanoaggregates exhibit high specific capacity of 868.7 C g −1 at 2 A g −1 in the wide potential window of −0.90 - 0.45 V in 3 M KOH. After 3000 cycles at 2 A g −1 , the electrode material retains 771.8 C g −1 . Even at high current density of 20 A g −1 , the electrode still delivers 456.1 C g −1 , which is outstanding of other Fe 3 O 4 nanomaterial for supercapacitor . Furthermore, the Fe 3 O 4 //AC asymmetry supercapacitor (3 M KOH as electrolyte) exhibits high energy density of 24.2 Wh kg −1 at power density of 801.1 W kg −1 with excellent cycling performance.