Highly efficient electrochemical energy storage of fluorinated nano-polyindoles with different morphology

Abstract The introduction of fluorine into a compound or material is known to impart a range of interesting functionalities; however, the poor electrochemical capacity of existing fluorinated polymers limits their application in the field of energy storage. Thus, we herein report the successful preparation of several fluorinated polyindole materials exhibiting high energy storage behaviours using a simple electropolymerization strategy. Scanning and transmission electron microscopic images reveal that the monofluorinated polyindoles are mainly composed of one-dimensional (1D) nanofibers and nanorods, whereas 1D nanowires and two-dimensional (2D) nanosheets are obtained for the difluorinated polyindoles. Interestingly, the prepared fluorinated polyindoles are found to exhibit the highest specific capacitances among all reported fluorinated materials (i.e., 261–528 F g−1 at 18 A g−1). In addition, they exhibit a good cycle stability as well as a high rate capability. Our results indicate that fluorinated nano-polyindoles can be considered as promising electrode materials for energy storage applications.