Scientists develop all-climate zinc-ion batteries with new hydrogel electrolyte

a. Schematic illustration of the design and construction of electrolyte structure; b. Schematic illustration of Zn plating behavior in Glu/ZC/PAM (left) and pure ZC (right). Credit: Li Zhaoqian.

Researchers have made a breakthrough in zinc-ion battery technology, creating a new hydrogel electrolyte that allows these batteries to operate efficiently in a wide range of temperatures.

This innovative approach, detailed in a study published in Advanced Energy Materials, could significantly enhance the performance and reliability of zinc-ion batteries in various climates.

The research team, led by Professor Hu Linhua from the Hefei Institutes of Physical Science at the Chinese Academy of Sciences, developed a hydrogel electrolyte using ClO4- anions and polyacrylamide chains.

This combination helps anchor water molecules, while glucose molecules regulate the behavior of zinc ions (Zn2+). The result is a more stable electrolyte that works effectively from -40°C to 130°C.

Team member Li Zhaoqian explained, “Our new electrolyte design means that aqueous zinc batteries can work reliably, regardless of seasonal and altitude changes.

We have systematically analyzed how the electrolyte interacts with Zn2+ and its interface with the electrodes, ensuring temperature resistance and stability.”

One of the main challenges with traditional zinc-ion batteries is that changes in temperature can cause the electrolyte to freeze or lead to unwanted side reactions.

The new hydrogel electrolyte addresses these issues by reducing the activity of water molecules, lowering the freezing point, and improving the moisture retention and stability of the electrolyte.

The researchers used advanced techniques like spectral analysis and theoretical calculations to understand how the new electrolyte works. They found that it delays the freezing point, retains moisture better, and prevents water-induced side reactions.

Additionally, simulations and morphological studies showed that the electrolyte has improved mechanical properties and forms a stable interface with the zinc electrodes, which helps prevent dendrite formation and ensures good contact between the electrolyte and electrodes.

The new electrolyte was tested in pouch batteries, showing impressive results. At -30°C, the batteries had a capacity of 254 mAh/g, and at room temperature, they reached 438.1 mAh/g. This performance is significantly better than previous batteries, which typically did not exceed 200 mAh/g at -30°C or 400 mAh/g at room temperature.

Further tests with Zn//Zn and Zn//Cu batteries showed that the new electrolyte provides a long lifespan and excellent performance.

The Zn anode lasted over 2,000 hours at low current density, and even at high current density, the battery operated steadily for more than 500 hours. The Zn//Cu batteries also performed well, working for over 800 hours with a high average Coulomb efficiency of 99.2%, making them highly competitive with previous hydrogel electrolytes.

This study demonstrates that the new hydrogel electrolyte effectively manages the coordination and thermodynamic activity at the electrolyte/Zn interface, reducing harmful reactions and extending the temperature range for operation.

It offers a safe and efficient solution for all-climate aqueous zinc-ion batteries, paving the way for more reliable energy storage solutions.