New technology for long-life of lithium-ion batteries for fast charging

• A simple process for treating the surface, rather than the materials inside the electrode, prevents irreversible lithium loss.
• High-energy-density anode coated with aluminum oxide (4.4 mAh/cm²) maintains more than 83.4% of its capacity (residual capacity ratio) even after 500 cycles of rapid charging.

Fast-charging technology has improved a lot with the widespread adoption of electric vehicles but has raised concerns about the long-life of lithium-ion batteries.

Fast charging is also essential for user convenience.

However, increasing the energy density of lithium-ion batteries necessitates thicker electrodes, which can lead to battery degradation and performance deterioration during rapid charging.

A team of researchers at Korea Electrotechnology Research Institute (KERI) Battery Materials and Process Research Centre in cooperation with a Hanyang University have developed a core technology to ensure the charging/discharging stability and long-life of lithium-ion batteries under fast-charging conditions.

To address this issue, the KERI team discovered a solution by partially coating the surface of the anode of the lithium-ion battery with aluminum oxide particles smaller than one micrometre.

Aluminum oxide

While many researchers worldwide have concentrated on the materials within the electrode, such as introducing functional nanotechnology into anode materials like graphite, researchers employed a straightforward processing technique to coat the electrode’s surface with aluminum oxide.

“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,” Dr. Choi Jeong Hee, Korea Electrotechnology Research Institute Battery Materials and Process Research Centre and researcher leader, said.

“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.”

Aluminum oxide is widely used in various ceramics due to low in cost, excellent in electrical insulation and heat resistance, chemically stable, and possessing good mechanical properties.

Scaling up the technology

The KERI researchers found that aluminum oxide particles effectively control the interface between the anode and the electrolyte in lithium-ion batteries, forming an interfacial highway for efficient Li+ transport.

This prevents the electrodeposition of lithium (an irreversible change that makes the lithium unavailable for additional charging and discharging) during fast charging, thereby ensuring the stability and lifespan of the lithium-ion battery during charging and discharging.

Through various tests, the team confirmed that the high-energy-density anode coated with aluminum oxide (4.4 mAh/cm²) maintains more than 83.4 per cent of its capacity (residual capacity ratio) even after 500 cycles of rapid charging.

They have verified this performance with pouch cells of up to 500mAh. The team is now planning to scale up the technology to make it applicable to large-area, medium- to large-capacity cells.