Capacitive behaviors for surface-sulfonated polyaniline nanofibers in different acidic electrolytes

Abstract Unique surface-sulfonated polyaniline nanofibers (PANI-S) were fabricated through one-pot polymerization to evaluate the feasibility of their applications as electrode materials for high-performance supercapacitors that can be operated in relatively weak acidic electrolytes. Benefiting from the self-doping effect and improved dispersion in aqueous solution for the nanofibers, as well as the effective buffering function of the electrolyte, the PANI-S exhibits excellent capacitive performance across a broad pH value range in acidic electrolytes. More clearly, the specific capacitance of the PANI-S remains remarkably stable, ranging from 752.4 to 754.4 F g −1 at a scan rate of 5 mV s −1 and from 575.4 to 536.8 F g −1 at a current density of 1 A g −1 , as the pH value of the electrolyte varies from 0 to 6. However, the capacity retention rate of PANI-S gradually decreases from 79.2% to 37.2% as the current density increases from 1 A g −1 to 20 A g −1 , with the pH of the buffered solution increasing from 0 to 6. The excellent electrochemical activity in low acidic electrolytes for PANI nanofibers can be attributed to the compensation effects of the self-doped local proton reservoir.