Renewable energy technologies, such as solar cells and wind turbines, are becoming increasingly widespread in many countries worldwide. Reliably storing the electricity produced by these devices, so that it can be used later at times when sunlight or wind are scarce, would further improve their effectiveness as sustainable energy solutions.
A promising solution to store solar and wind energy entails the use of aqueous zinc (Zn) metal batteries. These are low-cost, safe and environmentally friendly batteries that store and release energy, leveraging water-based solutions and Zn anodes.
Despite their potential, Zn batteries have not yet achieved the desired efficiencies and long-term stability. This is because water molecules can break down during their operation and small structures called Zn dendrites form on the surface of zinc electrodes, both of which were found to reduce performance.
Researchers at University of Maryland and the Brookhaven National Laboratory recently designed new aqueous electrolyte solutions that could help to improve the performance of Zn batteries. These electrolytes, presented in a paper published in Nature Nanotechnology, combine water with carefully selected salts that allow negatively charged ions (i.e., anions) to move closer to Zn ions, stabilizing the molecular structure that forms around Zn anodes.
“We developed water-in-salt electrolytes that extended the electrochemical stability window of aqueous electrolytes to 3.0V, enabling Zn batteries to achieve long cycle life,” Chunsheng Wang, senior author of the paper, told Tech Xplore. “However, water-in-salt electrolytes increase cost and viscosity and reduce ion conductivity. In this work, we developed low-concentration aqueous electrolytes that perform similarly to water-in-salt, with low viscosity, low cost, and high conductivity.”
New electrolytes for zinc batteries
The main goal of the recent work by Dr. Dejian Dong in Wang’s group was to design new electrolytes that could be used to extend the cycle life and boost the efficiency of Zn batteries, without increasing production costs. The solutions they created contain water and salts which have specific donor numbers that influence how they interact with Zn ions.
“We designed electrolytes with fluorinated anions that interact not only with Zn²⁺ but also with surrounding water molecules in the secondary solvation structure, forming an ‘anion-bridged secondary solvation sheath,'” explained Dong, the first author of the paper. “This structure helps protect Zn from water-induced side reactions, enables a more stable interphase, and maintains good transport properties.”
The researchers realized that aqueous electrolytes containing salts with donor numbers (i.e., indicators of Lewis basicity in chemistry) above 18 improved ion interactions inside Zn batteries. These salts were found to prompt the formation of a more stable molecular structure around zinc, reducing the formation of zinc dendrites and boosting the battery’s overall performance.
“The current electrolyte design, by regulating the primary solvation shell, faces the challenge of enhancing one property while sacrificing others,” said Dong. “The key innovation of this work is to overcome the aqueous electrolyte design limitation by regulating the secondary solvation structure, which can simultaneously enhance all the electrolyte properties.”
The researchers used their newly designed electrolytes to create Zn batteries and then tested these batteries in laboratory experiments. They found that the batteries achieved a remarkable coulombic efficiency of 99.99% over 1,000 operation cycles and energy densities of up to 130 Wh/kg.
A step towards improved grid energy storage solutions
This recent study opens new possibilities for the advancement of Zn batteries. The team’s design strategy could soon be used to create other aqueous electrolytes that contain similar concentrations of salts with desirable donor numbers.
“Our study offers a new perspective for electrolyte design, offering a pathway to simultaneously maintain high ionic conductivity, low cost and improved interfacial stability,” said Wang. “More broadly, it could have important implications for a wide range of electrochemical energy storage systems.”
In the future, the aqueous electrolytes developed by Wang and his colleagues could facilitate the commercialization and large-scale deployment of low-cost, safe and highly performing Zn batteries. These batteries could in turn make the storage of energy produced by renewable energy technologies more affordable and accessible.
“In our next studies, we plan to extend this concept to other types of electrolyte systems. We will also employ advanced characterization techniques and theoretical approaches to gain a deeper understanding of interfacial processes and their underlying mechanisms.” https://techxplore.com/news/2026-04-based-zinc-batteries-tackle-barrier.html
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