Advancements in wearable technology have spurred the need for lightweight and durable energy storage solutions. Meeting these demands requires technology capable of maintaining power retention and energy density under various mechanical deformations. Addressing this challenge, researchers at the Korea Institute of Science and Technology (KIST) have developed a fiber-like electrode material capable of storing energy, offering unprecedented versatility in wearable device design.
The team’s research, featured in Advanced Energy Materials, centers on fiber-shaped supercapacitors (FSSCs), which seamlessly conform to diverse shapes like conventional fibers. Carbon nanotube fibers (CNTFs) emerge as prime contenders owing to their superb electrical conductivity, strength, and flexibility.
Manufactured through a wet-spinning technique within a liquid crystal phase, these CNTFs showcase exceptional electrical conductivity, robust strength, lightweight, and flexibility, all stemming from their tightly packed and aligned structure composed of highly crystalline carbon nanotubes.
However, the clean surface of CNTFs poses limitations for chemical reactions necessary for energy storage. To enhance their energy storage capabilities, researchers typically add extra materials to the CNTFs’ surfaces, increasing the surface area for chemical reactions. Yet, this approach has drawbacks such as material detachment and impracticality for continuous fiber production.
In response, the KIST team developed specialized CNTFs capable of efficient energy storage without additional materials or processing steps. By treating the surface of CNTs and spinning them into fibers, they created a liquid crystal form, enhancing the fibers’ strength and electrical conductivity without sacrificing conductivity. These modified CNTFs exhibited significant improvements, including 33 times more energy storage, 3.3 times more strength, and 1.3 times more conductivity compared to regular fibers.
Testing their efficacy, the team utilized the fibers to power a digital clock, which functioned effectively for over 15 minutes. Fiber-shaped supercapacitors demonstrated impressive durability, retaining 95% of their performance after 5,000 bending tests and maintaining nearly perfect functionality when knotted. Furthermore, when incorporated into wrist straps of digital timepieces, the fibers exhibited resilience against bending, folding, and cleaning.
Dr. Kim Seung-min, a researcher at KIST, underscores the broader applicability of carbon nanotubes beyond conductive materials for secondary batteries, signaling potential advancements in diverse fields. The team aims to further explore unconventional energy storage applications and enhance fiber-type batteries’ energy density, expanding the technology’s utility beyond supercapacitors.