[SMM Analysis] Indonesian Team, Mixed Battery Lithium Recycling, Process Optimization and Efficiency Improvement

SMM February 21 News:

A research team from Gadjah Mada University in Indonesia and other institutions is dedicated to exploring innovative methods for recovering lithium from scrap lithium-ion batteries. The researchers successfully achieved a lithium recovery rate of up to 95.7% with a selectivity of 100% from ternary batteries by combining carbothermal reduction with water leaching under atmospheric conditions.

Currently, the global EV market continues to expand, and two types of lithium-ion batteries dominate the field. Among them, ternary batteries are well-known for their high energy density and suitability for long-distance EVs, while LFP batteries are favored for their high safety, good stability, and cost-effectiveness. However, the complex and diverse composition of scrap lithium-ion batteries poses significant challenges for recycling. In particular, the compositional differences between ternary batteries and LFP batteries further increase the complexity of the recycling process. This study focuses on using atmospheric water leaching to selectively extract lithium from the black mass of ternary batteries, addressing key challenges in the recycling process.

The researchers collected scrap ternary and LFP battery cathodes from local recycling sources and extracted the black mass as the primary material for processing. Subsequently, carbothermal treatment was conducted on different black mass mixtures (ranging from pure ternary to a 50:50 ratio of ternary and LFP, with treatment temperatures set between 750-950°C) and tested at heating rates of 5°C, 10°C, and 15°C per minute. After carbothermal treatment, water leaching was performed on the black mass to evaluate lithium recovery efficiency.

To analyze the process in depth, the researchers employed various analytical methods. Elemental composition was detected using inductively coupled plasma emission spectroscopy; phase and composition were determined via X-ray diffraction; surface morphology and elemental distribution were studied using scanning electron microscopy and energy-dispersive X-ray spectroscopy; functional groups in compounds were explored through Raman spectroscopy; and thermogravimetric analysis was conducted in the temperature range of 30-1,200°C to monitor heat and mass changes during the carbothermal reduction process in real time.

The study found that the heating rate during the carbothermal process significantly affects lithium recovery rates during water leaching. Specifically, lithium recovery rates decrease as the heating rate increases, with the highest recovery rate of 92.06±0.42% achieved at a heating rate of 5°C/min. This is because higher heating rates disrupt the uniformity of the reduction reaction, leading to uneven temperature distribution within particles and the formation of insoluble residual lithium compounds.

The target temperature also impacts the efficiency of carbothermal reduction. As the temperature increases, lithium recovery rates show a declining trend. Although thermogravimetric analysis indicates enhanced metal reduction at higher temperatures, lithium becomes embedded in Ni-Co alloy phases formed at these temperatures, resulting in reduced lithium recovery rates. X-ray diffraction results also confirmed the presence of these alloy phases, which hinder lithium extraction during the leaching process.

TGA analysis revealed significant mass changes during the carbothermal reduction of mixed LFP-ternary black mass, indicating potential reactions or phase/structural transformations in the solid material. Moreover, as the proportion of LFP in the mixed black mass increases, lithium recovery rates gradually decrease, particularly during carbothermal reduction at 950°C. Additionally, changes in treatment temperature have a relatively minor impact on lithium recovery from ternary-LFP mixtures. This suggests that the main challenges in the carbothermal reduction process of mixed battery black mass arise not from operational conditions but from chemical reactions between components, which generate compounds resistant to water leaching.

The study demonstrates that combining carbothermal reduction with atmospheric water leaching is an effective method for recovering lithium from mixed ternary-LFP battery black mass. Under optimized conditions (950°C, 15°C/min heating rate, 2-hour treatment time), lithium recovery efficiency from pure ternary black mass reached 95.7±0.31%, with a purity of 100%.

However, when an equal amount of LFP is added to the ternary black mass, the recovery process is disrupted, and lithium recovery rates drop significantly to 9.78±0.44%. This is due to the formation of water-insoluble Li3PO4 and the encapsulation of lithium within Fe-Ni-Co and Ni-Co alloy matrices.

To address this issue, the researchers added sodium carbonate during the carbothermal reduction process to suppress the formation of Li3PO4. This adjustment increased lithium recovery rates to 59.47%, while maintaining 100% purity by converting lithium into stable lithium carbonate. These findings suggest that in practical recycling applications, adding carbonate additives and reasonably adjusting process conditions could improve lithium recovery efficiency.

SMM New Energy Research Team

Cong Wang 021-51666838

Rui Ma 021-51595780

Disheng Feng 021-51666714

Ying Xu 021-51666707

Yanlin Lü 021-20707875

Yujun Liu 021-20707895

Xiaodan Yu 021-20707870

Zhicheng Zhou 021-51666711

He Zhang 021-20707850