An international team of researchers from Hanyang University, led by Professor Lee Jong-Won, and Kyunghee University, led by Professor Park Min-Sik, along with the Korea Electrotechnology Research Institute, under the direction of Dr. Jeong Hee Choi, has developed a key technology to guarantee the long-term stability of lithium-ion batteries under fast-charging conditions. This study was published in the journal Advanced Functional Materials.
KERI Dr. Choi Jeong Hee is holding an aluminum oxide dispersion (left) and the anode for a lithium-ion battery coating it on the anode. Image Credit: Korea Electrotechnology Research Institute (KERI)
Improving the driving range and safety of lithium-ion batteries is a critical requirement for the mass market adoption of Electric Vehicles (EVs). For the convenience of users, fast charging is also necessary, but thicker electrodes are required to increase the energy density of lithium-ion batteries, and this might cause the battery to degrade and its performance to decline during rapid charging.
The KERI team found a partial solution to this problem by partially covering the lithium-ion battery's anode's surface with aluminum oxide (Al2O3) particles smaller than 1 µm. While many researchers worldwide have concentrated on the materials within the electrode, such as introducing functional nanotechnology into anode materials like graphite, Dr. Choi's team employed a straightforward processing technique to coat the electrode's surface with aluminum oxide.
Low in cost, excellent in electrical insulation and heat resistance, chemically stable, and possessing good mechanical properties, aluminum oxide is widely used in various ceramics.
Aluminum oxide is not only low-cost and chemically stable but also excels in electrical insulation, heat resistance, and mechanical properties, making it ideal for use in various ceramic applications. It plays a crucial role in controlling the interaction between the anode and the electrolyte, creating a more efficient pathway for lithium ions. This efficient pathway helps prevent the irreversible electrodeposition of lithium during fast charging, enhancing the battery's stability and lifespan.
Another advantage of this technology is that it enables an increase in the energy density of lithium-ion batteries. Introducing other functional materials into the electrode's interior to improve performance and stability often complicates the synthesis process and reduces the amount of reversible lithium (initial coulombic efficiency). It also increases the electrode thickness, leading to performance deterioration under fast charging conditions.
However, the KERI technology involves surface treatment of the graphite anode rather than modifying the interior active graphite materials. This approach achieves stable performance even under fast charging conditions for high-energy-density thick-film electrodes without a loss in the amount of reversible lithium.
After conducting multiple tests, the researchers determined that the aluminum oxide-coated high-energy density anode (4.4 mAh/cm²) has exceptional performance, retaining over 83.4 % of its capacity (residual capacity ratio) even after 500 cycles of rapid charging. The technology has been tested in pouch cells up to 500 mAh and is now being scaled up for use in larger battery cells, promising significant advancements in battery performance for electric vehicles.
Convenient fast charging and the energy density of lithium-ion batteries have long been considered a trade-off, which has hindered the widespread adoption of electric vehicles, our work will help develop stable, high-energy-density lithium-ion batteries capable of fast charging. This advancement will contribute to the wider adoption of EVs and support the achievement of national carbon neutrality.
Dr. Jeong Hee Choi, Korea Electrotechnology Research Institute
The United States and Korea have both registered patents for this work, attesting to its brilliance.
KERI is a government-funded research institute housed within the Ministry of Science and ICT's National Research Council. The Samsung Future Technology Project and the Ministry of Trade, Industry, and Energy's Industrial Technology Innovation Project (high-power battery and charging system technology for EVs) provided funding for this research.
Journal Reference:
Choi, J., et al. (2024) Multi‐Interface Strategy for Electrode Tailoring Toward Fast‐Charging Lithium‐Ion Batteries. Advanced Functional Materials. doi.org/10.1002/adfm.202400414