Two-step method for synthesizing polyaniline with bimodal nanostructures for high performance supercapacitors

Here we report a novel and simple two-step method to fabricate polyaniline, which consists of two successive low-temperature (−20 °C, frozen) and near-room temperature (30 °C) periods. Melting of the frozen part and solute migration mainly drives polymerization. It is proved that the two-step method is an efficient way to fabricate polyaniline with a bimodal morphology composed of coral-like structure with thorns and interconnected nanowire structure. The mechanism of formation of such bimodal morphology is discussed in detail. Optimized polyaniline prepared by this method showed an excellent electrochemical energy storage performance, with a specific capacitance of 689 F g-1 at 1 A g−1 and a good retention rate of 89% (613 F g−1) at 10 A g−1. Symmetric cells based on it show an energy density of 12.6 Wh kg−1 at a power density of 188.3 W kg−1. In summary, this work provides a new way to fabricate polyaniline for supercapacitor applications.