With the development of smart wearable technology, people have put forward higher requirements on the flexibility, stretchability and portability of batteries.
In our daily life, we are not unfamiliar with rechargeable lithium-ion batteries, but whether to make rechargeable lithium-ion batteries into ultra-long fibers, or even into clothes?
That's what a team at the Massachusetts Institute of Technology (MIT) has done, developing the world's longest flexible fiber battery, a few hundred microns thick and 140 meters long, with a discharge capacity of 123 milliamps (mAh) and an energy of about 217 milliwatt-hours (mWh).
On December 20, 2021, A related paper was published in Materials Today under the title "Thermally Drawn Recommissioning Battery Fiber Enables and Pervacable Power."
This fiber battery has the "dual properties" of battery and fiber characteristics. It not only has the charge and discharge function of rechargeable lithium battery, but also can be woven into fabric to power a large number of non-planar electronic devices from 1D to 3D power supply, providing more options for wearable electronic devices.
Jung Tae Lee, a professor at Kyung Hee University's School of Life Sciences and corresponding author of the paper, told the media: "The advantage of our method is that multiple devices can be embedded in a single fiber. This differs from other approaches that require the integration of multiple fiber-optic devices. As we integrate these fibers with multiple devices, the aggregation will advance the realization of compact fabric computers."
The fiber cell continues to power the LED even after it is partially cut, indicating that the fiber cell system is free of electrolyte loss and short circuit (source: Materials Today)
This study is the first to accommodate multiple complex electroactive gels, particles, and polymers simultaneously within a protective flexible envelope using thermal stretching. Another advantage of the hot drawing process is that the lateral dimension of the fiber can be controlled by varying the winch speed without changing the premold.
Made from a new battery gel as well as a standard fiber stretching system, the system starts with a cylinder containing all the components and then heats it to just below its melting point. When the researchers took the material out of the narrow opening, they found that all the parts were a fraction of their original diameter, while keeping the arrangement of the parts intact.
Graphic * Includes a variety of gels for thermal fiber cell stretching and its extension into 2D and 3D flexible multidimensional electronic products (Source: Materials Today)
Previous research in this area has focused on braided, washable leds, photoelectric sensors, communications and digital systems. They are suitable for use in flexible wearable products, but the disadvantage is that they rely on external power sources and cannot be self-powered.
So, can fiber batteries be as comfortable to wear as ordinary clothes, but also have the charge and discharge function of batteries for self-powered communication, sensing and computing devices?
ot stretched fiber cells (right) are refractory due to gel electrodes and gel electrolytes, while controlled fiber cells with liquid electrolytes (left) immediately catch fire and expand (source: Materials Today)
Tural Khudiyev, a postdoctoral research associate at MIT's Research Laboratory of Electronics and the paper's lead author, said: 'When we embed active materials inside the fibers, it means that sensitive battery components are already well sealed. And because all the active materials are so well integrated, they don't change their position."
The MIT team's new fiber cell is not only self-powered, it also meets the requirements of a portable electronic system that is machine washable, flexible, underwater and fire/rupture safe.
Not only that, but the fiber cell also enables 3D printing in one step. In addition to the appearance of the battery fiber, there are various metals and active materials inside the fiber. "This is the first 3D printing of a fiber cell device." "Said Tural Khudiyev.
The team demonstrated power for submarine drones, Li-Fi (Light Fidelity) fabrics, and flying drone communications with different rechargeable fiber battery solutions, which lays a good foundation for the development of battery-powered electronics.
Munster university physics chemistry professor Martin Winter (Martin Winter) think the study is very creative, he said: "the shape of the new battery unit flexibility can meet the design and application of impossible before, now, most studies have looked at about battery power storage and electric vehicles, this is a great deviation from the mainstream."
The length of the fiber cell has not reached its limit, and the team says it hopes to increase it to more than 1,000 meters in the future. Next, the team will focus on how to further improve the efficiency and power capacity of the battery. In addition, the technology has applied for related patents, and they hope the technology will be commercialized in a few years.