Preparation of stable composite porous nanofibers carried SnOx-ZnO as a flexible supercapacitor material with excellent electrochemical and cycling performance

Abstract

Flexible and portable supercapacitors as a variety of energy storage devices are used in wearable electronic devices. However, the practical application of flexible supercapacitors is still restricted by comparatively poor performance. Herein, we have successfully prepared porous carbon nanofibers supported Sn and Zn bimetallic composites as flexible and freestanding electrode material in supercapacitors. Sn element encapsulated in nano-fiber films were prepared by electrospinning technique, the SnOx-ZnO/MCNFs composites were formed by immersion of different proportions of Zn2+, and further high temperature carbonization process. In addition, on the basis of comparative experiments, a possible mechanism for effective synergy between the two metals were raised. The specific capacitance of SnOx-ZnO/MCNFs-10 mmol/L at 0.5 A g−1 is 783 F g−1 with the retention rate of 87% after 5000 cycles, which is higher than their respective counterparts SnOx/MCNFs (599 F g−1) and ZnO/MCNFs (429 F g−1). Moreover, a flexible all-solid-state asymmetric supercapacitor (ASC) was further assembled with the energy density of 37.7 Wh kg−1 at the power density of 374.9 W kg−1, and long-term cyclic stability (76.2% after 5000 cycles). The reason for the remarkable electrochemical performance could be the reasonable combination of the two electrode materials, which provides a new idea for the application of composite materials in supercapacitors.