Supercapacitors, which offer rapid charge–discharge and high stability, are attracting attention as next-generation energy storage devices for high-power applications such as automobiles, robots, and telecommunications equipment. With much higher power density than conventional secondary batteries, they are evaluated as a technology that can complement batteries in renewable energy systems with large power fluctuations and electronic devices that require instantaneous high power. However, development of electrode materials to increase energy storage capacity has remained a key challenge.

Previously, research focused on improving performance by combining metals with carbon materials. However, metal particles tended to agglomerate during high-temperature processes, leading to performance deterioration. This reduced the active surface area for energy storage and resulted in decreased stability over long-term use.

To address these supercapacitor issues, the research team of Jeonbuk National University (JBNU) Professor Kim Jeong-gil (Department of Secondary Battery Engineering) and Professor Gil Myung-seop (Department of Organic Materials and Textile Engineering) introduced gamma-ray irradiation technology.

The team introduced cobalt metal onto the surface of carbon nanofibers and then applied gamma-ray irradiation to realize a nanostructured electrode material in which carbon and cobalt are uniformly bonded. As a result, rod-shaped carbon–cobalt structures grew uniformly, forming bonded structures that facilitated electron transport, producing a high-performance supercapacitor electrode.

In particular, by controlling the dose of gamma irradiation, they confirmed the potential to optimize a single material for use as both the positive and negative electrodes. The developed electrode achieved both high power density and energy density, and demonstrated long-term stability by retaining 97% of its initial capacity even after more than 20,000 charge–discharge cycles.

This research outcome also draws attention as a valuable achievement of the newly established Department of Secondary Battery Engineering, created this year to respond to future advanced industrial demand as part of the Glocal University 30 Project. JBNU established the Department of Secondary Battery Engineering last year and began operating it this year with an enrollment capacity of 30 students. Through this program, it aims to foster professionals who will lead the secondary battery field through education and research encompassing energy storage materials, electrode design, and system applications.

Professor Kim Jeong-gil said, "The gamma-ray irradiation method is an example that demonstrates it can precisely control the microstructure and interfacial bonding between carbon and metal, beyond a simple surface treatment technique," and added, "The convergence of textile engineering and secondary battery engineering is significant in that it advanced both the energy storage mechanism and material design simultaneously."

Meanwhile, the study was published in the world-leading composites journal Composites Part B: Engineering (IF=14.2, top 0.3%), and Dr. Chae Su-hyeong of the Department of Secondary Battery Engineering participated as the first author. The research was supported by the National Research Foundation of Korea.