Zinc‐Air Battery Operated with Modified‐Zinc Electrodes/Gel Polymer Electrolytes

Abstract

AbstractZinc‐air batteries (ZABs) have anodic challenges to overcome such as passivation, shape changes, and hydrogen evolution. In this work, zinc anodes were electrosynthesized on carbon paper electrodes using organic additives (Zn/CP) to investigate their viability as an alternative to benchmarked Zn foils. Additionally, the typical aqueous electrolyte (6 M KOH) was replaced by a gel polymer electrolyte (GPE) to assist Zn/CP to decrease anodic issues. In 6 M KOH, the current density of the ZAB with Zn/CP was 42 mA cm−2 @ 0.6 V vs. 28 mA cm−2 for Zn foil. However, chronopotentiometric tests demonstrated that the ZAB with Zn foil possessed a higher stability. SEM images after the stability tests and tests by linear‐sweep voltammetry revealed that Zn/CP suffers a higher formation of hydrogen gas, promoting such morphological changes, decreasing the number of active sites and, thus, stability. The aqueous media was then replaced by the GPE based on polyacrylic acid cross‐linked with potassium (PAAK). Tests revealed that the GPE at different compositions (from 3 to 10 wt.%) significantly decreased the Zn issues, where the GPE at 3 wt.% of PAAK was the most favorable composition, providing comparable current/power densities to the obtained at 6 M KOH (40 vs. 42 mA cm−2 and 25.2 vs. 26.8 mW cm−2).