South Korea's KIST Develops 1-Meter Fiber Battery That Retains Performance

Researchers in South Korea have developed a method to continuously produce fiber-shaped zinc batteries in lengths of up to one meter, a significant advancement from the previous 10-centimeter standard. This breakthrough was achieved by a team led by Dr. Kim Nam-dong and Dr. Jung Hyun-soo at the Korea Institute of Science and Technology (KIST) Bionics Research Center in collaboration with Jeonbuk National University, KAIST, and Kangwon National University. By introducing oxygen functional groups onto carbon nanotubes, the team was able to suppress dendrite growth, a common issue that affects battery life and efficiency. This innovation allowed the battery to retain 85% of its initial capacity after 800 charge-discharge cycles and 89.8% after 10,000 bending tests. The process involves an automated continuous electroplating line that includes fiber feeding, plating, washing, drying, and winding. The team demonstrated the battery's potential by integrating it with flexible solar cells and motion sensors in a battle uniform, suggesting applications in wearables and humanoid robot joints.

The fiber-shaped battery technology, which can be woven into fabrics and bent like cloth, offers a new power source for smart clothing, electronic skin, wearable sensors, and humanoid robots. Zinc batteries, known for their water-based electrolytes, are considered a safer alternative to lithium-ion batteries due to their lower risk of fire or explosion. However, commercialization has been hindered by dendrite growth on the zinc anode and the limitation of production lengths to around 10 centimeters. The introduction of oxygen functional groups on carbon nanotubes addresses these issues by encouraging uniform zinc ion adhesion and reducing hydrogen and corrosion reactions during charge-discharge cycles.

The research, published in Advanced Energy Materials, highlights the fiber-shaped battery's performance metrics, with the battery maintaining 85% of its initial capacity after 800 cycles. The continuous electroplating system developed by the team enables the production of 1-meter-long batteries, significantly longer than previous versions. The battery also retained 89.8% of its capacity after 10,000 bending cycles, demonstrating its durability.

The practical application of this technology was showcased through a battle uniform that combines the fiber-shaped battery with flexible solar cells and motion sensors. This system can charge via sunlight during the day and power sensors at night. The battery can be cut to the desired length or woven with other fibers, offering versatility in design.

Dr. Kim Nam-dong emphasized the importance of combining material and process technologies to address the challenges of dendrite growth and manufacturing length in fiber-shaped zinc batteries. Despite the advancements, challenges remain in commercialization, including the need to increase production speed, ensure uniform plating across long electrodes, and verify long-term stability under conditions such as sweat and washing. The lack of standardized evaluation criteria and mass-production equipment also poses challenges to cost competitiveness.

The development of this technology is attracting attention for its potential to transform power design in the wearable and robotics industries. Unlike traditional lithium-ion batteries that require separate housing, these weavable batteries can integrate power sources directly into clothing or a robot's shell. For South Korea's battery materials and equipment industry, the continuous plating process for fiber-shaped electrodes could generate new equipment demand.