New fibers that collect and store electricity in clothing

May 24. () –

Researchers at the Applied Physics Laboratory (APL) at Johns Hopkins University have established new, scalable methods to develop fibers powered by batteries and solar energy.

These fibers, which make it theoretically possible to harvest electrical energy from clothing and store it in them, could power high-performance wearable electronic devices that breathe, stretch and wash like conventional textiles, they say.

This development in fiber energy sources (submillimeter thick batteries and photovoltaic threads that could be woven directly into fabrics) opens a new world of wearable electronics and smart textiles. Instead of wearing a heart monitor with bulky batteries, a patient could wear a shirt that has battery- and solar-powered fibers woven into it. Clothing powered by this fiber could be heated to keep a person warm in cold environments, or provide soldiers with hands-free audio and video recording on the battlefield.

“As demands for e-textiles change, there is a need for smaller power sources that are reusable, durable and extensible,” he said. it’s a statement Konstantinos Gerasopoulos, deputy director of the physics, electronic materials and devices program at APL and principal investigator of this project. “Our vision is to develop solar harvesting fibers that can convert sunlight into electricity and battery fibers that can store the electricity generated in the textile.”

Manufacturing and design have limited the scalability and performance of fiber batteries. Industrial textile equipment has been used to make fiber batteries, but its massive scale limits its use to specialized facilities that are not compatible with the battery industry. Standard fiber batteries also suffer from lower performance because the electrodes are usually twisted together, which leaves most of the electrode surface inactive.

NEW MANUFACTURING METHOD

Now, in a study published May 22 in Advanced Materials Technologies, APL scientists have demonstrated a novel method for scaling up fiber battery manufacturing.

Instead of using textile equipment, the APL team customized the battery equipment to achieve the thinness required for fiber batteries. This strategy, including the creation of custom roll-to-roll configurations, made the process portable and suitable for large-scale production. All of the equipment needed to create the fiber batteries could fit in a small room.

“We always design with roll compatibility in mind,” said Rachel Altmaier, lead author of the paper. “We need to be able to run all of our processes continuously or else what we develop will not be relevant. This process could be incorporated into an existing manufacturing line.”

The batteries are made of flat strips of anode and cathode electrodes and a polymer separator that are fed together into a heated roller press and laminated into a stacked design. The construction is similar to conventional portable batteries and provides greater power and performance than standard fiber batteries. The stack is then laser cut into a fiber-like strand approximately 700 micrometers wide, approximately the width of five human hairs.

This marks the first use of laser cutting on a complete battery stack and demonstrates the feasibility of the method for customizing battery size while maintaining performance. The speed of the cutting system also makes it scalable.

“We can process 100 meters of total fiber in just over five hours,” said Jason Tiffany, an APL engineer and co-author of the paper. “With our process, we can make the fibers smaller and more energy dense, which could open up even more opportunities for textile applications.”

The work with fiber batteries adds to the team’s technological toolbox, which has included the development of a flexible lithium-ion battery that can operate in extreme conditions, as well as safe, fast-charging batteries.

THEY CAPTURE LIGHT AND CONVERT IT INTO ELECTRICITY

In a second paper published May 22 in Advanced Functional Materials, the APL team also addressed the challenge of making high-performance, scalable fibers that can capture light and convert it into electricity. “As with the battery fibers, we were inspired by conventional solar cell technology, which is very efficient and robust,” Gerasopoulos said. “We asked, how can we convert these energy sources into fibers?”

The researchers cut and assembled tiny solar cells into thin, flexible circuit boards before sealing them in a protective polymer to create a fiber-like strand. which was woven with nylon to form a small fabric.

“The biggest challenge with current solar cell technology is its rigidity,” said Michael Jin, lead author of the solar cell paper. “You can imagine that shrinking solar panels, like those found on a roof, down to a small solar fiber is a big challenge.”

To overcome this challenge, the team took advantage of a specific type of solar cell that has positive and negative terminals on the back in a finger shape. From this cell, the researchers cut and assembled small solar cells onto a thin, flexible circuit board.