Tailoring Entangled Sodium Alginate in Quasi‐Solid Electrolyte to Augment Air Pockets for Superior Zn‐Air Battery at Low Temperature

Zinc-air batteries (ZABs) face performance challenges due to sluggish oxygen reduction reactions. Increasing electrolyte viscosity is proposed using sodium alginate and KOH enhancing the triple-phase boundary at the electrolyte-cathode interface. This method improves power output and durability at low temperatures with low catalyst mass loading offering a promising design strategy.

Abstract

The increasing impact of climate change along with technological advancements is driving the need for reliable and efficient rechargeable batteries which can perform in low-temperature conditions. Rechargeable zinc-air batteries (ZABs) have emerged as promising candidates that offer advantages such as high energy density, low cost, safety, and environmental friendliness. However, achieving high power density and cycling stability with low catalysts in ZABs at low temperatures remains a challenge. Herein, this study proposes the critical role of air pockets at the electrolyte-cathode interface to amplify the triple-phase boundary (TPB) and enhance ZAB power output. A quasi-solid electrolyte (QSE) based on sodium alginate (SA) is developed to address these challenges. The high concentration of KOH inhibited SA ionization which resulted in entangled SA aggregates in the QSE. The deformability and form stability of the QSE helped generate and maintain numerous air pockets at the electrolyte-cathode interface. Despite extremely low catalyst loading of 0.04 mg_Pt cm⁻², the ZAB achieved a power density of 233 mW cm⁻² at room temperature and excellent cycling stability over 480 h at −20 °C. This work provides valuable insights into designing efficient ZABs for low-temperature applications, offering a promising solution for harsh climate environments.