Constructing ZnCo2O4@LDH Core-Shell hierarchical structure for high performance supercapacitor electrodes

In this article, ZnCo2O4 nanowires deposited with two kinds of typical layered double hydroxides (Ni-Al,Co-Al LDH) are developed via scalable method. Two materials all display core-shell hierarchical structure. High specific capacitance of 2041 F g(-1) and 1586 F g(-1) are obtained for ZnCo2O4@Co-Al LDH and ZnCo2O4@Ni-Al LDH,respectively. Combining with active surface and synergistic effect, the role of hierarchical structure in enhancing performance is revealed. Moreover, two all solid state supercapacitors based on fabricated materials as positive electrodes, activated carbon as negative electrodes and PVA-KOH as polymer electrolyte are assembled. The maximum power and energy densities of ZnCo2O4@Co-Al LDH//AC are 6200 W kg(-1) and 50.1 Wh kg(-1), respectively. While the power and energy densities of ZnCo2O4@Ni-Al LDH//AC are 3400 W kg(-1) and 27.8 Wh kg(-1). At last, an energy storage-conversion system, based on solar cell as input device and assembled asymmetric supercapacitor ZnCo2O4@Co-Al LDH//AC as output device, is integrated as a self-sustaining power device, indicating its potential in practical applications.