Ternary ZnO/Co3O4/NiO inherited layered core-shell structure from a double template for high performanced supercapacitor

Abstract Relying on seed method, a double template ZIF-8@ZIF-67 with a layered core-shell structure was made, which is used as a sacrificial template in the next steps. After going through loading process with solvent thermal method and calcination process, ZIF-8@ZIF-67 was etched and calcined into ternary ZnO/Co3O4/NiO successfully. Besides, benefiting from right amount of the addition of inorganic salts, the optimized ZnO/Co3O4/NiO-2 (ZCN-2) shows the outstanding performance in its morphologic structure and electrochemical performance. In the case of a current density of 1 A g-1, the high specific capacitance of 1119.11 C g-1 can be calculated in ZCN-2. In addition, at 10 A g-1, the capacitance value can maintain 93.75% after experiencing 5000 cycles of charging and discharging. The maximum energy density of the assembled ZCN-2//activated carbon (AC) asymmetric supercapacitor can reach 95.82 Wh kg-1, which is really outstanding in the present research achievements. After experiencing charge-discharge cycles with the number of 10000 times in the case of a current density of 10 A g-1, the cycling stability of this supercapacitor can reach 94.53% of the initial value. And after a charge, the device connected by two supercapacitors can make a light emitting diode (LED) shine up to 30 minutes successfully.