Low-temperature tolerant poly(acrylic acid) (PAA) gel polymer electrolytes for rechargeable zinc-air batteries

Gel polymer electrolytes (GPEs) are emerging materials for Zn-air batteries (ZABs), since the GPE can act as a combined electrolyte and separator in the battery. GPE-KOH was fabricated through the polymerization of poly(acrylic) acid in the presence of KOH and ZnO. GPE-KOH-KI was fabricated following a similar procedure, followed by immersion in a solution containing KOH, KI, and ZnO. The addition of KI to the electrolyte changed the conventional charging reaction to a reaction with a lower thermodynamic barrier, which improved the battery efficiency with a maximum increase of 36% relative to ZABs without KI. This work focused on extending the working temperature range of the ZAB to low temperatures (as low as -41 degrees C) as well as exploring the reaction mechanism for ZABs using KI as an additive. It is proposed that the discharging reaction at the air electrode is a combination of the oxygen reduction reaction and iodate reduction reaction.