Researchers cut and assembled tiny solar cells on thin, flexible circuit boards before sealing them in a protective polymer to create a fiber-like strand that was woven with nylon into a small textile.
In an ambition to develop versatile wearable electronic devices, researchers from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland established new scalable approaches to developing battery- and solar-powered fibers.
This technology can be woven into clothing that has the potential to harvest and store electrical energy, as per a statement by scientists.
Due to usual fiber batteries being hindered by scalability and performance limitations, the scientists engineered fiber batteries with a stacked design akin to conventional pouch cells.
The approach involves layer lamination and laser machining to devise battery fibers with widths as narrow as 650–700 µm
Tech Xplore noted that these fibers could power high-performance wearable electronics that breathe, stretch, and wash just like conventional textiles.
Laminating conventional battery electrodes for wearable devices
“As demands for electronic textiles change, there is a need for smaller power sources that are reusable, durable, and stretchable,” stated Konstantinos Gerasopoulos, assistant program manager for physics, electronic materials and devices at APL and the lead investigator of this project.
“Our vision is to develop solar harvesting fibers that can convert sunlight to electricity and battery fibers that can store the generated electricity in the textile.”
The key to this progress is the development of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) separators. These allow the lamination of conventional battery electrodes using a heated rolling press as per the study.
The laminated strips are then laser-cut to form fibers, which have been successfully tested, showing that the energy density of the fiber batteries can store up to 0.61 milliwatt-hours of energy per centimeter of fiber length.
The fiber batteries have also been designed to be equipped in a roll-to-roll fashion. This signified a departure from former methods due to the new approach delivering optimal utilization of active materials, low content of inactive materials, scalability, and compatibility with widely used battery industry equipment.
“We were always designing with roll-to-roll compatibility in mind,” noted Rachel Altmaier, the study’s lead author.
“We need to be able to run all of our processes continuously or else what we develop isn’t relevant. This process could be dropped into an existing manufacturing line.”
The battery equipment was custom-made into thin, scalable fibers employing a roll-to-roll process upon which the laminated flat strips of anode and cathode electrodes with a polymer separator into a stack. This was laser-cit into thin fibers.
Processing 100 meters of fiber in over five hours
“We can process 100 meters of total fiber in a little over five hours,” articulated Jason Tiffany, an engineer at APL and co-author of the paper. “With our process, we can make the fibers smaller and more energy-dense, which could open even more opportunities for textile applications.”
However, the solar-powered fibers were adapted from conventional solar cell technology by assembling them onto flexible circuit boards. They were then encapsulated in polymer allowing the integration into textiles. Despite extensive bending and exposure to light, this method proved to provide high performance and durability.
“The biggest challenge with current solar cell technology is its rigidity,” emphasized Michael Jin, lead author of the solar cell paper. “You can imagine shrinking solar panels, like those on a rooftop, into a tiny solar fiber is very challenging.”
“We used standard microelectronics fabrication processes to develop a novel approach that has transformed current rigid solar cell technology into flexible and durable fibers,” Jin added.
“Even after bending the fiber 8,000 times, we saw no change in its performance.”
The new device could enable various applications such as health monitoring, warming clothing, and providing power for soldiers’ equipment.
This new study represents a paradigm shift in fiber battery technology, paving the way for the realization of high-performance wearable and textile electronics.
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“Textiles that integrate light energy harvesting and battery fibers could revolutionize what wearables today can achieve. Very soon, these fibers will enable distributed fabric-based power, heating, communications, and sensing while providing the comfort and ease of regular textiles,” stated Jeff Maranchi, research program area manager in APL’s Research and Exploratory Development Department.
The study was published in the journal – Advanced Materials Technologies and Advanced Functional Materials.
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Shubhangi Dua As a quirky and imaginative multi-media journalist with a Masters in Magazine Journalism, I'm always cooking up fresh ideas and finding innovative ways to tell stories. I've dabbled in various realms of media, from wielding a pen as a writer to capturing moments as a photographer, and even strategizing on social media. With my creative spirit and eye for detail, I've worked across the dynamic landscape of multimedia journalism and written about sports, lifestyle, art, culture, health and wellbeing at Further Magazine, Alt.Cardiff and The Hindu. I'm on a mission to create a media landscape that's as diverse as a spotify playlist. From India to Wales and now England, my journey has been filled with adventures that inspire my paintings, cooking, and writing.