Good news! As is too often the case, the abstract of this research paper is way too technical and narrowly focused.
"... Researchers ... recently designed new aqueous electrolyte solutions that could help to improve the performance of Zn batteries. These electrolytes ... 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," ... "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." ..."
"Researchers ... have developed a new electrolyte design strategy that significantly improves the efficiency and stability of aqueous zinc metal batteries, offering a promising pathway toward low-cost, safe, and long-duration energy storage. ...
In their study, the engineering researchers propose a new architecture that enables the electrolyte to simultaneously combine several desirable properties: strong ion pairing without salt precipitation, high ionic conductivity, and a protective layer against water-induced side reactions. Testing demonstrated remarkable performance improvements, with an average coulombic efficiency of 99.99% over 1,000 cycles, a metric that measures how well batteries retain charge during use. ..."
From the abstract:
"Aqueous zinc metal batteries are low-cost electrochemical devices suitable for safe grid energy storage. However, water decomposition and Zn dendrite formation detrimentally affect their coulombic efficiency.
Conventional aqueous electrolyte solutions, with a concentration around 1 M, are cost-effective and exhibit high bulk ionic conductivity but cannot form a stable solid electrolyte interphase.
Water-in-salt and aqueous–organic hybrid electrolyte solutions can form robust solid electrolyte interphases, but they are not kinetically efficient and cost-effective.
Here, to circumvent these issues, we design variously concentrated aqueous electrolyte solutions using several salts with different donor numbers to extend anion coordination into the secondary solvation sheath.
We show that salt-derived anions with donor number > 18 enter the Zn2+ first solvation sheath, and ensure a strong binding energy between the Zn2+(H2O)5-anion nanometric clusters and water molecules in the secondary solvation sheath. In particular, 2 M aqueous electrolyte solutions containing fluorinated anions exhibit bulk ionic conductivities of 26–35 mS cm−1 at 25 °C and form a ZnF2-rich solid electrolyte interphase.
When tested in Zn||NaV3O8·1.5H2O Swagelok cells, the best-performing electrolyte solution enables an average coulombic efficiency of 99.99% for 1,000 cycles at 1.5 mA cm−2, corresponding to an initial specific energy of 130 Wh kg−1 (based on the combined weight of the positive and negative electrodes)."
University of Maryland Engineers Design New Electrolytes for Aqueous Zinc Batteries (original news release)
