Phosphoric acid/glycerol-based anti-freezing organohydrogel electrolyte for flexible supercapacitor with excellent low-temperature stability

Abstract

Flexible supercapacitors (SCs) have attracted much attention from researchers on account of their excellent safety, high power density, fast charging/discharging speed and long cycle life. Conventional hydrogel electrolytes will freeze when the operating temperature drops below zero degree, limiting the practical applications of SCs. Here, we proposed a strategy to prepare a highly conductive organohydrogel electrolyte (OHE) with excellent anti-freezing property and moisture retention by soaking poly(2-acrylamido-2-methypropane sulfonic acid)/poly (acrylamide) (PAMPS/PAAm) hydrogel into phosphoric acid/glycerol (PA/Gly) co-solvent. The OHE possessed favorable flexibility and excellent electrical conductivity of 9 and1.98 S/m at room temperature and −40 °C, respectively. Meanwhile, the prepared SCs obtained high specific capacitance, superior capacitance retention rate of 75.65% and excellent mechanical flexibility at −40 °C, compared with those at room temperature. Moreover, this work would provide a novel and promising approach for the development of flexible wearable electronic devices with low-temperature stability.