Tri-Electrode Structured Zinc-Air Batteries: A Leap in Energy Storage Efficiency and Stability

Abstract

Rechargeable zinc-air batteries (ZABs) are gaining attention as a potent solution for large-scale energy storage, offering high capacity and an environmentally friendly profile. Utilizing zinc, an abundant and cost-effective alternative to lithium, ZABs capitalize on the plentiful oxygen in ambient air, presenting a more sustainable option than traditional lithium-ion batteries. In this work, we address the operational challenges of ZABs, primarily focusing on the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) that occur during the discharge and charge cycles. ORR, a three-phase reaction, necessitates efficient water management and high-performance electrocatalysts, while OER is a two-phase reaction prone to creating oxygen bubbles that can damage the electrode structure. A critical issue in ZABs is the instability of ORR catalysts during the OER phase, and vice versa. To counter this, we propose a tri-electrode cell structure that separates the ORR and OER electrodes, allowing each to be optimized independently. This design enhances the stability and overall efficiency of the batteries. In our study, MnO2/C deposited on nickel foam was employed as the ORR electrode, and layered double hydroxides (LDHs) deposited directly on stainless steel mesh served as the OER electrode. A graphite electrode was used as the common negative electrode. Our proposed system, tested at 100 mAh/cm² and 25 mA/cm², demonstrated remarkable durability, sustaining at least 100 cycles with a Coulombic efficiency of 98% and a 60% roundtrip efficiency. These findings offer valuable insights into the future design of stable, high-efficiency rechargeable zinc-air batteries, marking a significant step forward in sustainable energy storage technology.