Ultra-low temperature flexible supercapacitor based on hierarchically structured pristine polypyrrole membranes

Abstract Low-temperature flexible supercapacitors (LFSCs) are urgently needed because most supercapacitors become rigid and prone to damage at extremely low temperatures, such as in the winter of the northern atmosphere, at high altitude, and in space. Although extensive investigations on anti-freezing electrolytes have significantly promoted the development of low-temperature resistant supercapacitors, a usable LFSC remains a major challenge because of the inferior capacitance and flexibility of the existing electrodes at low-temperature. Herein, a supercapacitor prototype that remained flexible and energy storage functional at −50 ℃ was demonstrated, thanks to a hierarchically-structured self-standing pristine polypyrrole membrane (PPy-N) that showed high flexibility and electrochemical performances at ultra-low temperature. With PPy-N as the electrodes, the assembled supercapacitor possessed a high cyclic stability (88.9% capacitance retention after 1000 cycles) as well as an outstanding flexibility (only 9.6% capacitance decay when bent to 180°) at −50 ℃. Furthermore, the PPy-N supercapacitors in series stably powered electronic devices even when repeatedly bent in a dry ice bath. Such remarkable performances make this flexible PPy-N electrode a promising candidate for the LFSCs.