High-performance binary cross-linked alkaline anion polymer electrolyte membranes for all-solid-state supercapacitors and flexible rechargeable zinc–air batteries
Development of a high-performance alkaline anion-exchange membrane (AAEM) is a subject of intense research owing to its potential applications in polymer electrolyte membrane fuel cells, supercapacitors and zinc–air batteries. However, high ionic conductivity is still a major challenge for AAEM. Herein, we developed a novel binary cross-linking strategy by employing glutaraldehyde (GA) and pyrrole-2-carboxaldehyde (PCL) as binary cross-linkers for fabricating a highly conductive, flexible and thin AAEM composed of poly(vinyl alcohol)/guar hydroxypropyltrimonium chloride (PGG-GP). The resultant PGG-GP membrane delivered an exceptional hydroxide conductivity of 0.123 S cm−1 at room temperature, while retaining high swelling resistance, outstanding mechanical strength and excellent thermal stability. An activated carbon-based all-solid-state supercapacitor exploiting the PGG-GP membrane as an electrolyte demonstrated a long cycling life of 8000 charge/discharge cycles with 87.5% capacitance retention. Moreover, the flexible all-solid-state zinc–air batteries comprising the PGG-GP polymer electrolyte displayed a peak power density of 50.2 mW cm−2 and a superior cycling stability (9 h @ 2 mA cm−2). These merits make the PGG-GP membrane very promising for application in both all-solid-state supercapacitors and flexible, rechargeable zinc–air batteries, providing new opportunities for improving the ionic conductivity in all-solid-state devices.