Researchers at MIT in the US have developed a rechargeable lithium-ion battery in the form of an fibre that could be woven into fabrics.
As a proof of concept the team produced the world’s longest fibre battery at 140 meters long with a process that could produce a battery as long as 1km. The 140m fibre has an energy storage capacity of 123 mAh to charge smartwatches or phones and is only a few hundred microns in diameter, making it suitable for weaving into materials for wearable systems.
The fibre battery is manufactured using new electrolyte gels and a standard fibre-drawing system that starts with a larger cylinder containing all the components and then heats it to just below its melting point. The material is drawn through a narrow opening to compress all the parts to a fraction of their original diameter, while maintaining all the original arrangement of parts.
This embeds the lithium and other materials inside the fibre, with a protective outside coating, thus directly making this version stable and waterproof. “There’s no obvious upper limit to the length. We could definitely do a kilometre-scale length,” says researcher Tural Khudiyev, who is now an assistant professor at National University of Singapore.
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“This is the first 3D printing of a fibre battery device,” said Khudiyev. “After printing, you do not need to add anything else, because everything is already inside the fibre, all the metals, all the active materials. It’s just a one-step printing. That’s a first.”
“When we embed the active materials inside the fibrer, that means sensitive battery components already have a good sealing and all the active materials are very well-integrated, so they don’t change their position,” he said. The aspect ratio is up to a million, making it practical to use standard weaving equipment to create fabrics that incorporate the batteries as well as electronic systems.
A demonstration device uses the fibre battery to power an LED and receiver in a LiFi light-based communication system. The team has also embedded multiple LEDs into the fibre.
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