Atomic-Level Tin Regulation for High-Performance Zinc–Air Batteries

Abstract

The trade-off between the performances of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) presents a challenge in designing high-performance aqueous rechargeable zinc-air batteries (a-r-ZABs) due to sluggish kinetics and differing reaction requirements. Accurate control of the atomic and electronic structures is crucial for the rational design of efficient bifunctional oxygen electrocatalysts. Herein, we designed a Sn-Co/RuO₂ trimetallic oxide utilizing dual-active sites and tin (Sn) regulation strategy by dispersing Co (for ORR) and auxiliary Sn into the near-surface and surface of RuO₂ (for OER) to enhance both ORR and OER performances. Both theoretical calculations and advanced dynamic monitoring experiments revealed that the auxiliary Sn effectively regulated the atomic/electronic environment of Ru and Co dual-active sites, which optimized the *OOH/*OH adsorption behavior and promoted the release of the final products, thus breaking the reaction limits. Therefore, the as-designed Sn-Co/RuO₂ catalysts exhibited superb bifunctional performance with an oxygen potential difference (Δ<i>E</i>) of 0.628 V and negligible activity degradation after 200,000 (ORR) or 20,000 (OER) CV cycles. The a-r-ZABs based on the Sn-Co/RuO₂ catalyst exhibited a higher performance at a wide temperature range of -30 to 65 °C. They demonstrated an ultralong lifespan of 138 days (20,000 cycles) at 5 mA cm^-2, 39.7 times higher than that of Pt/C + IrO₂ coupled catalysts at a low temperature of -20 °C. Additionally, they maintained an initial power density of 85.8% after long-term tests, significantly outperforming previously reported catalysts. More importantly, the a-r-ZABs also showed excellent stability of 766.45 h (about 4598 cycles) at a high current density of 10 mA cm^-2.