More stability for fast charging electric car batteries

May 31. () –

South Korean scientists have developed a core technology to ensure charge/discharge stability and long life of batteries. fast charging lithium ion batteries.

A crucial prerequisite for widespread adoption of electric vehicles is the improvement of the performance of lithium-ion batteries in terms of autonomy and safety. Fast charging is also essential for user convenience. However, increasing the energy density of lithium-ion batteries requires thicker electrodes, which may lead to battery degradation and performance deterioration during fast charging.

To address this problem, the KERI (Korea Electrotechnology Research Institute) team discovered a solution by partially coating the surface of the lithium-ion battery anode with aluminum oxide (Al2O3) particles smaller than 1 micrometer. While many researchers around the world have focused on the materials inside the electrode, such as introducing functional nanotechnology into anode materials such as graphite, Dr. Choi Jeong Hee’s team employed a simple processing technique to coat the surface of the electrode. electrode with aluminum oxide.

Low cost, excellent electrical insulation and heat resistance, chemically stable and with good mechanical properties, aluminum oxide is widely used in various ceramics. KERI researchers found that aluminum oxide particles effectively control the interface between the anode and electrolyte in lithium-ion batteries, forming an interfacial highway for efficient Li+ transport. This prevents lithium electrodeposition (an irreversible change that makes lithium unavailable for additional charges and discharges) during fast charging, thus ensuring the stability and life of the lithium-ion battery during charging and discharging.

Another advantage of this technology is that it allows an increase in the energy density of lithium-ion batteries. The introduction of other functional materials inside the electrode to improve performance and stability often complicates the synthesis process and reduces the amount of reversible lithium (initial Coulomb efficiency). It also increases the thickness of the electrode, leading to a deterioration in performance under fast charging conditions. However, KERI technology involves treating the surface of the graphite anode, rather than modifying the active graphite materials inside. 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.

Through various tests, the team confirmed that the high energy density anode coated with aluminum oxide (4.4 mAh/cm2) exhibits first-class performance, maintaining more than 83.4% of its capacity (capacity ratio). residual) even after 500 quick charge cycles. They have verified this performance with pouch cells up to 500 mAh. The team is now planning to expand the technology to be applicable to large area and medium to large capacity cells.

“The convenient fast charging and energy density of lithium-ion batteries have long been considered a trade-off, which has hindered the widespread adoption of electric vehicles,” Dr. Choi said. “Our work will help develop stable, high-energy-density lithium-ion batteries capable of rapid charging. This advancement will contribute to broader adoption of electric vehicles and support the achievement of national carbon neutrality.”

The excellence of this work has been demonstrated by patent registrations in both Korea and the United States. The findings were also published in a recent issue of Advanced Functional Materials.