A Quick and Easy Way to Produce Anode Materials for Sodium-Ion Batteries Using Microwaves

A research team has developed a groundbreaking process technology that enables ultrafast, 30-second preparation of hard carbon anodes for sodium-ion batteries, using microwave induction heating.

April 1, 2025

Korea Electrotechnology Research Institute, Changwon, Korea

(Front row, from left) Dr. Daeho Kim and Dr. Jong Hwan Park of KERI have developed a groundbreaking process technology to ultrafast preparation of hard carbon, an anode material for sodium ion batteries, using microwave induction heating technology. (Image: Korea Electrotechnology Research Institute)

The research team led by Dr. Daeho Kim and Dr. Jong Hwan Park at the Nano Hybrid Technology Research Center of the Korea Electrotechnology Research Institute (KERI) has developed a groundbreaking process technology that enables ultrafast, 30-second preparation of hard carbon anodes for sodium-ion batteries, using microwave induction heating.

One of the next-generation secondary batteries, the sodium-ion battery uses sodium (Na) in lieu of lithium (Li). Sodium, the main component of salt, is more than a thousand times more abundant than lithium and is easier to extract and refine. Furthermore, its lower reactivity compared to lithium means greater electrochemical stability when used for batteries, making it more favorable for fast charging and discharging, while maintaining performance even at low temperatures.

Despite these advantages, sodium-ion batteries face significant challenges, including lower energy density and shorter lifespan compared to lithium-ion batteries due to the complexity of the manufacturing process. The larger size of sodium ions compared to lithium necessitates the use of hard carbon, which has a larger interlayer spacing than graphite, the current mainstay of anode materials.

Hard carbon is not found in nature and therefore must be synthesized. The preparation process is highly intricate, requiring hydrocarbon materials — the main components of plants and polymers — to be heated in an oxygen-free environment at temperatures exceeding 1000 °C for extended periods. This “carbonization” process is both economically and environmentally burdensome, which has been a key obstacle to the commercialization of sodium-ion batteries.

Among the many teams trying to address this challenge, the team led by Dr. Kim and Dr. Park proposed a rapid heating method using the microwave technology that is used in kitchen microwave ovens. They first created films by mixing polymers with a small amount of highly conductive carbon nanotubes. They then applied a microwave field to the films to induce currents in the carbon nanotubes, selectively heating the films to over 1,400 °C in just 30 seconds.

Through years of research, KERI has developed a technology to uniformly heat-treat conductive thin films, such as metals, using microwave fields. This technology has attracted considerable attention in industrial processes such as displays and semiconductors. KERI’s Nano Hybrid Technology Research Center is recognized as the nation’s leading center for carbon nanomaterials technology. Dr. Kim and Dr. Park leveraged the center’s capabilities to venture into sodium-ion battery anode materials and achieved promising results.

The key to their success lies in the team’s own multiphysics simulation technique. It allowed them to have a profound understanding of the complex processes occurring when an electromagnetic field in the microwave band is applied to nanomaterials, leading to the creation of a novel process for preparing sodium-ion battery anode materials. The significance of the team’s findings has been demonstrated by the recent publication of their results in the Chemical Engineering Journal. The paper was co-first-authored by Geongbeom Ryoo and Jiwon Shin, student researchers who participated in KERI’s academia-research collaborative research program.

“Due to recent electric vehicle fires, there has been growing interest in sodium-ion batteries, which are safer and function well in colder conditions. However, the carbonization process for anodes has been a significant disadvantage in terms of energy efficiency and cost,” said Dr. Park. Dr. Kim added: “Our microwave induction heating technology enables fast and easy preparation of hard carbon, which I believe will contribute to the commercialization of sodium-ion batteries.”

Moving forward, the team plans to continue working to improve the performance of their anode materials and develop technology for the continuous mass production of large-area hard carbon films. They also see the potential of their microwave induction heating technology applicable to other fields, such as all-solid-state batteries that require high-temperature sintering, which warrants further research.

KERI, having already completed a domestic patent application, expects this technology to attract significant interest from companies involved in energy storage materials and anticipates technology transfer deals with potential industry partners.

For more information, contact Dr. Daeho Kim at This email address is being protected from spambots. You need JavaScript enabled to view it..