Micromorphology-controlled synthesis of polypyrrole films by using binary surfactant of Span80/OP10 via interfacial polymerization and their enhanced electrochemical capacitance

Porous polypyrrole (PPy) free-standing films are prepared by the self-assembly of a mixture of two long-chain surfactants (Span80 and OP10) via interfacial polymerization. The micromorphology of synthesized PPy is investigated by scanning electron microscope (SEM), while its electrochemical performance is evaluated by the means of cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results show that the morphology of obtained PPy can be controlled from ruptured vesicle-like structure to network-like structure, then to coral-like structure by tuning the HLB (Hydrophile-Lipophilic Balance) value of mixed surfactant in the synthetic process, and the HLB value plays a crucial role in improving the electrochemical performances of as-prepared PPy. Particularly, interconnected PPy network bonded with ∼800 nm PPy particles could be perfectly prepared at HLB value of 10.4. Because of its larger active surface area, more excellent conductivity and higher porosity than other samples, the maximum specific capacitance and energy density are obtained up to 286 F g−1 and 39.7 Wh kg−1, respectively, at a current density of 0.5 A g−1. Furthermore, 88.6% of the initial specific capacitance is retained even after 2000 cycles.