KIER Researchers Unveil Single-Step Direct Recycling Method for Spent EV Batteries

As global adoption of electric vehicles accelerates, managing end-of-life battery packs has become a significant technical and environmental priority for the automotive and clean technology sectors. Conventional recycling methods often rely on hydrometallurgical operations that generate substantial wastewater laden with heavy metals, creating severe environmental contamination risks for surrounding soil and groundwater.

Direct recycling has emerged as an appealing alternative because it preserves the complex structural framework of cathode materials while conserving expensive critical minerals such as cobalt. However, the approach has long been hindered by the difficulty of detaching current collectors—the metal foils strongly bound to active cathode compounds to sustain electrical conductivity during repeated charge cycles. Separating these elements historically required hazardous chemical solvents, leaving toxic residues that degraded the storage capacity of recovered materials, as first reported by TechXplore.

To solve this systemic bottleneck, a research team led by Dr. Jung-Je Woo at the Gwangju Clean Energy Research Center within the Korea Institute of Energy Research (KIER) engineered a streamlined, solution-based recycling technique. The newly developed method eliminates the need to dissolve active materials, providing a simpler chemical path toward industrial-scale battery recovery.

The core process involves submerging spent cathode assemblies in a diethylene glycol solution maintained at 130 degrees Celsius. Thermal exposure causes the diethylene glycol to undergo an oxidation reaction, transforming it into glycolaldehyde. Because glycolaldehyde reacts readily with adjacent molecular structures, it weakens the powerful adhesive bond between the cathode material and the metal current collector, permitting complete mechanical separation.

Simultaneously, the chemical oxidation releases free electrons that drive lithium ions back into the depleted crystal matrix of the cathode. This dual mechanism allows the delamination of the current collector and the electrochemical rejuvenation of the cathode—known as lithiation—to occur in a single operational step.

During laboratory evaluations published in the journal Advanced Science, the KIER research group applied the treatment to nickel-manganese-cobalt (NCM) and lithium iron phosphate (LFP) cathode formulations, which represent the majority of standard EV battery chemistries. The regenerated NCM material recovered 99.1% of its original baseline capacity, while the restored LFP material achieved 99.7% of its pristine energy retention capability.

The researchers also validated the technique using degraded material taken from a 50-ampere-hour (Ah) commercial EV battery cell. When reassembled into a small test pouch cell, the regenerated cathode material increased discharge performance from an initial 30.6 milliampere-hours (mAh) to 34.6 mAh, confirming the practical viability of the process for real-world automotive supply chains.

"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," said Dr. Jinju Song of KIER, who led the study. "The process is simple and does not require specialized sealed processing environments, giving it strong potential for industrial application."