A Long-Lasting Rechargeable Seawater Zn–Air Battery Enabled by Vacancy-Driven Co3O4–MoS2 Bifunctional Cathodes

The global energy crisis and unsustainable reliance on fossil fuels make it particularly urgent to develop efficient renewable energy storage solutions. Aqueous zinc–air batteries (ZABs) have become extremely promising candidates due to their low cost, abundant surface resources, inherent safety, and high theoretical energy density. This study explores the feasibility of using seawater as an electrolyte for ZABs, with the aim to reduce costs and alleviate competition for limited freshwater resources. Research results indicate that ZABs using seawater electrolytes with varying salinities (1.4–10%) show good bifunctional catalytic performance in the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) with defect-driven Co3O4–MoS2 bifunctional catalysts, while maintaining strong catalytic activity and stability in nonextreme salinity environments. The assembled ZABs with defect-driven Co3O4–MoS2 bifunctional catalysts display a charge–discharge voltage difference of less than 1.1 V, can stably operate for more than 360 cycles at a current density of 5 mA/cm2, and exhibit strong tolerance to halogen ions, with performance comparable to that of batteries using conventional deionized water-based electrolytes. These findings underscore the feasibility of seawater-based ZABs, breaking through the limitations of traditional deionized water-based electrolytes and expanding the application prospects of aqueous ZABs in the realm of sustainable energy storage.