- Diethylene glycol solution enables complete separation of current collectors from spent cathode materials while simultaneously regenerating the cathode materials
- NCM and LFP cathode materials recover 99.1% and 99.7% of their capacity, respectively, demonstrating performance comparable to pristine materials
- Research published in Advanced Science (IF 14.1), a leading international journal

As the adoption of electric vehicles (EVs) continues to grow, the disposal of spent EV batteries is emerging as a major social and environmental challenge. Wastewater generated during conventional battery recycling processes can contain high concentrations of heavy metals, posing risks of soil and groundwater contamination.

Cathode materials*, which play a key role in determining battery capacity, also contain significant amounts of costly critical metals such as cobalt, whose extraction can cause environmental damage. As a result, direct recycling technologies for spent batteries, which can preserve the existing structure of battery materials while recovering valuable resources, are gaining increasing attention.

* Cathode material: A key battery component that stores and releases lithium ions during charging and discharging, playing an essential role in the generation of electrical energy

Against this backdrop, a research team led by Dr. Jung-Je Woo of the Gwangju Clean Energy Research Center at the Korea Institute of Energy Research (KIER) has developed a technology that completely separates current collectors, one of the major technical challenges in the direct recycling of spent batteries. The team also succeeded in simultaneously regenerating spent cathode materials to a performance level comparable to that of pristine materials.

The key to the newly developed technology lies in the complete separation of the current collector from the cathode material. Current collectors facilitate the flow of electricity within batteries and are strongly bonded to cathode materials so that they remain firmly attached during repeated charging and discharging. During battery recycling, however, this strong adhesion has traditionally required the use of specialized solutions containing hazardous chemicals to dissolve the bonding components. In addition, residual substances generated during this process can remain on the cathode material, potentially degrading the performance of the regenerated electrodes. As a result, current collector separation has remained a major challenge in direct battery recycling.

To overcome this limitation, the research team developed a solution-based recycling process. When spent cathode materials are immersed in a diethylene glycol solution and heated to 130°C, the diethylene glycol undergoes oxidation to form glycolaldehyde. Because glycolaldehyde readily interacts with other molecules, it weakens the adhesion between the cathode material and the current collector, enabling complete separation of the current collector. At the same time, electrons generated during the oxidation of diethylene glycol facilitate the replenishment of lithium ions in the cathode material, enabling delamination and regeneration occur simultaneously in a single step.

Using the developed process, the researchers regenerated NCM and LFP cathode materials, both widely used in electric vehicles. The regenerated NCM cathode recovered 99.1% of the capacity of pristine material, while the regenerated LFP cathode recovered 99.7%, demonstrating performance nearly equivalent to that of pristine cathode materials.

* NCM: A lithium-ion battery cathode material containing nickel, cobalt, and manganese.

* LFP: A lithium-ion battery cathode material containing lithium, iron, and phosphate (lithium iron phosphate).

The researchers also applied the technology to degraded cathode material from a 50-ampere-hour (Ah) EV battery and fabricated it to a small pouch cell using the regenerated material. The discharge capacity increased from 30.6 milliampere-hours (mAh) to 34.6 mAh, demonstrating the potential of the technology for regenerating cathode materials recovered from actual EV batteries.

Dr. Jinju Song of KIER, who led the study, said, “This technology enables spent battery cathode materials to be recycled without dissolving the active material, making it an environmentally friendly approach that can reduce both wastewater-related pollution and energy consumption.” She added, “The process is simple and does not require specialized sealed processing environments, giving it strong potential for industrial application.”

This research was supported by the Ministry of Trade, Industry and Resources (MOTIR) and the Ministry of Science and ICT (MSIT) of the Republic of Korea. The findings were published in the September 2026 issue of Advanced Science (IF 14.1), a leading international scientific journal.