Carbon nanofibers decorated with Sn and ZnO via 2-methylimidazole functionalization for high-performance supercapacitors

The development of advanced energy-storage systems and renewable energy technologies to meet the energy demands of automotive and consumer electronics is driving the integration of supercapacitors as critical components in these applications. This study explored the effect of incorporating dual metal salts (Sn and Zn) into carbon nanofibers (CNFs) on the supercapacitor performance. The surface-modified Sn-ZnO@CNF was synthesized using a self-template strategy, wherein zinc ions embedded in the nanofibers acted as precursors to develop thorny zeolitic imidazolate framework (ZIF) structures on the fiber surface. Furthermore, surface treatment with 2-methylimidazole (2MI) successfully increased the electrochemically active surface area (ECSA) from 902 to 2029 cm² g⁻¹, increasing the areal capacitance by approximately 55% in a potential window of 0–1.6 V. This composite electrode achieved a maximum specific capacitance of 1.31 F cm⁻² at a current density of 2 mA cm⁻², and it retained 90% of its initial capacitance after 30,000 charge–discharge cycles.