Construction of controllable multicomponent ZnO-ZnCo/MOF-PANI composites for supercapacitor applications

Abstract

Supercapacitors, as new electrochemical energy storage (EES) devices, with the lower energy density seriously hinder their realization of the requirements for future high energy storage devices. Thus, It is crucial to develop straightforward and efficient approaches to address the aforementioned challenges in future EES devices. In this paper, controllable multi-component composites are designed and ZnO is used as a conductive carrier in preparing layered structured ZnO-Zn/Co-metal-organic framework-polyaniline (ZnO-Zn/Co-MOF-PANI, ZZCMP) electrode materials by solvothermal and electrodeposition methods. The abundant active sites and the high specific surface area of the MOF are used to create the conditions for the loading of PANI, while it can establish an effective ion/electron transport channel with PANI to enhance the material utilisation and the electrochemical performance of the overall material. Add to that, the advantages of flexibility and rigidity of pristine MOF are made use of to provide sufficient space during the process of long-term charging and discharging, thus facilitating resistance to the structural deformation and enhancing the mechanical stability of the material. The optimized integrated electrode ZZCMP-10 exhibits a capacitance of 458.9 F.g−1 when operated at a current density of 1 A.g−1. The asymmetric supercapacitor (ASC) is constructed with ZZCMP-10 as the positive electrode material and active carbon is used as the material for the negative electrode, which shows an energy density of 26 Wh.kg−1 at a current density of 1 A.g−1 and a retention of 75.3 % capacitance is achieved after 5000 cycles of long-term charging and discharging. This study provides a reasonable exploration for designing high-energy-density electrochemical energy storage devices.