A research team has developed a fast and simple method for making hard carbon anodes for sodium-ion batteries using microwave technology.
This new process takes just 30 seconds and could help make sodium-ion batteries more affordable and environmentally friendly.
The research, led by Dr. Daeho Kim and Dr. Jong Hwan Park from the Korea Electrotechnology Research Institute (KERI), was published in the Chemical Engineering Journal.
Sodium-ion batteries are considered a promising alternative to the commonly used lithium-ion batteries. Unlike lithium, sodium is much more abundant and easier to extract and refine.
It also offers greater electrochemical stability, meaning sodium-ion batteries could charge and discharge faster and perform better in cold temperatures.
However, sodium-ion batteries face challenges, particularly with energy density and lifespan, partly due to the larger size of sodium ions.
This requires the use of hard carbon, a material with larger spaces between its layers, to create the anodes for these batteries.
The problem is that hard carbon does not exist naturally and must be synthesized through a complex process called carbonization, which involves heating materials to over 1,000°C in an oxygen-free environment.
This process is both expensive and energy-intensive.
To solve this problem, Dr. Kim and Dr. Park’s team proposed using microwave induction heating, similar to how a microwave oven works.
By mixing polymers with carbon nanotubes, which are highly conductive, they created films that could be heated quickly and uniformly using microwaves.
When exposed to a microwave magnetic field, the nanotubes in the film heated up rapidly, raising the temperature to over 1,400°C in just 30 seconds, creating hard carbon anode material.
This microwave-based method makes the process much faster, easier, and more energy-efficient than traditional carbonization.
The researchers used a special technique called “multiphysics simulation” to better understand how the electromagnetic fields interact with the nanomaterials. This helped them fine-tune the process for preparing sodium-ion battery anodes.
Dr. Jong Hwan Park explained that sodium-ion batteries are gaining interest due to their safety and performance in colder conditions, especially after recent concerns about lithium-ion battery fires. Dr. Daeho Kim added that their new microwave technology could help overcome the cost and efficiency challenges associated with the traditional carbonization process.
The research team is now working to improve the performance of these anode materials and develop a system for mass-producing hard carbon films on a larger scale. They also see potential applications for their microwave technology in other areas, such as all-solid-state batteries that require high-temperature processing.
KERI has already filed a patent for this new technology and expects to attract significant interest from companies working with energy storage materials, potentially leading to technology transfer deals in the future.
