13 June 2025
Fluorine-free electrolytes could pave the way for safer next-generation batteries
Researchers at Luleå University of Technology have developed and tested new fluorine-free electrolytes – a potential key to safer and more environmentally friendly batteries in the future.
Today’s batteries often rely on fluorinated compounds that offer high performance but come with significant risks – both to the environment and to safety during manufacturing and recycling. Some of these substances can form PFAS, a group of so-called “forever chemicals.”
“Fluorinated salts and solvents cause serious safety issues, from production to recycling,” says Yanqi Xu, researcher in Chemistry of Interfaces at Luleå University of Technology.
In his recently defended doctoral thesis, he designed, synthesized and tested several completely new electrolytes – the liquid inside a battery that transports ions between the electrodes. The materials contain no fluorine but still demonstrated promising properties in lab tests: they tolerate heat and humidity, work at high voltages, and show compatibility with lithium in small-scale battery cells.
Lab results with unexpected behavior
One of the most promising electrolytes is sodium-based and showed an unusual trait: its conductivity improved as more salt was added – the opposite of what’s typical.
“We saw that the ionic conductivity increased with salt concentration, which is very interesting for future applications,” says Yanqi Xu.
He also developed borate-based salts that performed well even after weeks of exposure to humid air – a common weakness in battery materials. He then built coin cells using his own developed electrolytes and tested how they performed during repeated charging and discharging cycles.
Early-stage research – but with strong potential
The technology is still at the lab scale, and there’s a long road ahead before it could be used commercially. But the results show that it’s possible to develop electrolytes free from fluorinated substances – without sacrificing battery performance.
“I believe this could contribute to society and the green transition,” says Yanqi Xu.
“Fluorine-free, less flammable and lower-cost materials – that could be the future of batteries.”
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