A new development could change how we store energy, making zinc batteries last longer, work more efficiently, and avoid problems that limit current technology.
Researchers at the University of Maryland and Brookhaven National Laboratory have developed a new aqueous electrolyte system that significantly improves the performance of zinc metal batteries, enabling up to 99.99% coulombic efficiency over 1,000 cycles and energy densities of about 130 Wh/kg. The advance strengthens the case for zinc batteries as a low-cost, safe option for large-scale energy storage.
The work addresses a central limitation of aqueous zinc batteries: poor long-term stability caused by water-driven side reactions and the formation of zinc dendrites, which degrade electrodes and shorten battery lifespan. These issues have prevented widespread deployment despite the technology’s inherent advantages in safety and cost.
Rather than relying on conventional “water-in-salt” electrolytes, which improve stability but suffer from high cost, viscosity, and reduced conductivity, the researchers designed low-concentration aqueous electrolytes with optimized ion interactions. Their strategy focuses on tuning the chemical environment beyond the immediate zinc ion, targeting what is known as the secondary solvation structure.
By selecting salts based on their donor numbers and incorporating fluorinated anions, the system forms an “anion-bridged secondary solvation sheath.” This structure strengthens interactions between zinc ions, surrounding water molecules, and anions, stabilizing the electrolyte environment. As a result, water decomposition is suppressed and dendrite formation is reduced, improving both efficiency and cycling stability.
This approach differs from traditional electrolyte design, which typically focuses only on the primary solvation shell. By engineering the broader solvation network, the researchers achieved simultaneous improvements in stability, ion transport, and conductivity without major trade-offs.
In laboratory testing, the new electrolyte enabled zinc batteries to maintain high efficiency and stable performance over extended cycling, outperforming conventional aqueous and water-in-salt systems.
Future work will focus on refining these electrolyte systems and using advanced modeling and experimental tools to further understand interfacial ion behavior in battery operation.