Fabrication of a flexible quasi-solid-state asymmetric supercapacitor device based on a spherical honeycomb like ZnMn2O4@Ni(OH)2 hybrid core-shell electrode material with superior electrochemical performances

Abstract

Supercapacitors have drawn our attention exceptionally in the last few decades due to their substantial applications, but the majority has focused on different metal oxides/metal hydroxides composite electrode materials. Here, we have synthesised spherical honeycomb like ZnMn2O4@Ni(OH)2 (ZMN) core–shell electrode material by a facile, substrate free and cost-effective hydrothermal protocol. The novel electrode material, such as spherical ZMN exhibits high specific capacitance of 2577.44F g−1 at 1 A g−1 with incredible cyclic stability of 94.8% capacitance retention after 3000 cycles a 1 A g−1. Additionally, a solid-state asymmetric device has been fabricated by using ZMN and activated carbon (AC) as positive and negative electrodes, respectively. This asymmetric device exhibits a high energy density of 43.17 Wh kg−1 at a power density of 374.98 W kg−1 and retains a very high energy density of 15.18 Wh kg−1 at the power density of 5972.9 W kg−1. More importantly, this device holds a long-term cycling stability, with ≈ 90.46 % capacity retention after 10,000 cycles at 1 A g−1. These results reveal high potential for making an ASC device with high energy and power densities for electronic applications.

Keywords

• Honeycomb
• Spherical core–shell
• Asymmetric supercapacitor
• Power density