Fluoro-substituted conjugated polyindole for desirable electrochemical charge storage materials

Abstract

Fluoropolymers have great values in the scientific research and the industrial application, but poor electrochemical properties restricted their use as charge storage materials. In this work, we developed a high-performance poly(5-fluoroindole) (5-PFIn) as charge storage material by simple electrodeposition of 5-fluoroindole in acetonitrile solution containing 0.1 M Bu4NBF4. The morphologies, structures and electrochemical properties of as-prepared 5-PFIn were studied by SEM, FT-IR, UV–vis, BET and electrochemical techniques, respectively. The electrochemical results indicated that the 5-PFIn nanowires in 1.0 M H2SO4 electrolyte showed a full-covered strongly responsive redox behavior between −0.4 V and 0.85 V, which remarkably differed from polyindole (PIn) and poly(5-methoxyindole) (5-PMeOIn) and poly(indole-5-carboxylic acid) (5-PICA). As a result, 5-PFIn exhibited high specific capacitance of 416 F g−1 at 10 A g−1, good cycling stability of 83% after 5000 cycles and slow self-discharge behavior, which were superior to those of PIn (103 F g−1, 68%), 5-PMeOIn (114 F g−1, 70%) and 5-PICA (286 F g−1, 70%). These results indicated that the fluorine-substituted conjugated PIn will be one of the most promising fluoropolymers electrode materials for supercapacitor application.