A novel synthesis of controllable nitrogen-doped SnOx-ZnO supercapacitors to enhance electrochemical performance

Abstract

Nitrogen-enriched carbon nanofibers carried Sn and Zn bimetallic composites with outstanding storage capacity and superior mechanical strength were facilely fabricated by electrospinning technology, amidoximation reaction modified polymer fiber, ion coordination technique introduced Zn2+ and carbonization of composite nanofibers. The introduction of amidoxime groups not only enhanced the coordination ability with Zn2+, but also increased the content of nitrogen element. In addition, due to the different thermal stability of amidoxime groups, the regulation of different types of nitrogen content can be achieved by changing the carbonization temperature, and the influence of nitrogen on the electrochemical performance was explained. At the same time, due to the role of carbothermal reduction, tin in different valence ratios was obtained and its contribution to the energy storage performance of supercapacitors was explored. Benefiting from high nitrogen-enriched level, mutation between Sn2+ and Sn4+ oxidation state and synergistic mechanism of ZnO-SnOx bimetal, the prepared composite had a high specific capacitance of 810.89 F g−1 at a current density of 0.5 A g−1, outstanding cycling stability of 119% over 5000 cycles in 4 M KOH electrolyte. What’s more, we conducted a two-electrode test with the energy density of 50 Wh kg−1 at a power density of 374 W kg−1. In consequence, this novel design is believed to have great potential in high energy and power density of energy storage devices in the future.