Key Takeaways & Executive Findings
- •• A green organic acid reagent scheme (MSA and CA) effectively leaches Co and Li from spent LiCoO2 cathodes, achieving up to 92% Co and 85% Li extraction under optimized conditions. • The leaching process is chemical reaction-controlled with activation energies around 50 kJ/mol for both Co and Li, as confirmed by Avrami equation fitting. • Cobalt is efficiently recovered from the leachate via oxalic acid precipitation, yielding 99.91% precipitation efficiency and high-purity cobalt oxalate (99.85 wt.%). • This environmentally friendly hydrometallurgical approach offers a sustainable alternative to conventional inorganic acid leaching, reducing environmental impact while maintaining high metal recovery.
Abstract
This study focuses on using a green reagent scheme of methanesulfonic acid (MSA) and citric acid (CA) to extract valuable metals from the cathodes, aiming to minimize environmental impact during the recycling process. Leaching studies on LiCoO2 identified optimal conditions as follows: 2.4 mol/L MSA, 1.6 mol/L CA, S/L ratio of 80 g/L, leaching temperature of 90oC and leaching time of 6 h. The maximum Co and Li extraction achieved was 92% and 85%, respectively. LiCoO2 dissolution in MSA-CA leaching solution is highly impacted by temperature; Avrami equation showed a good fitting for the leaching data. The experimental activation energy of Co and Li was 50.98 kJ/mol and 50.55 kJ/mol, respectively, indicating that it is a chemical reaction-controlled process. Furthermore, cobalt was efficiently recovered from the leachate using oxalic acid, achieving a precipitation efficiency of 99.91% and a high-purity cobalt oxalate product (99.85 wt.%). In the MSA-CA leaching solution, MSA served as a lixiviant, while CA played a key role in reducing Co in LiCoO2. The overall organic acid leaching methodology presents an attractive option due to its reduced environmental impact.
1. Introduction
Battery materials and superalloys are the primary drivers of cobalt demand globally, with over half of the demand attributed to lithium-ion batteries. The electric vehicle (EV) sector has emerged as the primary consumer of cobalt, now commanding a staggering 40% share of total cobalt demand, a figure set to double by 2030, largely propelled by battery applications within EVs. Despite ongoing efforts to substitute cobalt in battery chemistry, projections suggest that cobalt-containing cathodes will continue to dominate the market for at least a decade due to the lag in commercializing new technologies [1]. Meanwhile, lithium cobalt oxide (LiCoO2), the most cobalt-intensive cathode material, is primarily used in portable electronics and accounts for about 80% of the portables market.
The lithium-ion battery market is predominantly shared by Asia Pacific, Europe, and North America. However, despite this widespread demand, over 70% of the world’s cobalt is sourced from the Democratic Republic of Congo, posing a significant risk to the security of cobalt supply in major importing countries. Cobalt recycling from scrap, particularly from hard alloy and spent lithium-ion batteries, emerges as a crucial strategy to bridge the gap between supply and demand domestically in the long term [2]. Despite this, scrap volumes remain relatively low, with secondary volumes comprising only around 5% of total cobalt supply, a proportion that has seen marginal growth in recent years. Although major companies like Li-Cycle, Redwood, CALT, and BRUMP are actively recycling spent batteries, only about 50% are currently being recycled, leaving room for significant market expansion. While secondary cobalt supply from recycling has historically contributed minimally, projections suggest a significant rise to 15% by 2030 and exceeding 40% by 2040, necessitating substantial investment and collaboration to develop regionalized supply chains, particularly in North America and Europe.
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WU Jia-jia, KIM Jaeyeon, AHN Junmo, LEE Jaeheon (2025). Metal extraction and recovery from cathode material of spent lithium-ion batteries utilizing an organic acid reagent scheme. Journal of Central South University. https://doi.org/10.1007/s11771-025-6081-5
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Frequently Asked Questions
What is the optimal leaching condition for extracting metals from spent LiCoO2 using organic acids?
The optimal conditions are 2.4 mol/L methanesulfonic acid (MSA), 1.6 mol/L citric acid (CA), a solid-to-liquid ratio of 80 g/L, a temperature of 90°C, and a leaching time of 6 hours, achieving up to 92% Co and 85% Li extraction.
How is cobalt recovered from the leachate in this study?
Cobalt is recovered by precipitation using oxalic acid, achieving a precipitation efficiency of 99.91% and producing high-purity cobalt oxalate (99.85 wt.%).
What is the role of citric acid in the leaching process?
Citric acid acts as a reducing agent, reducing Co(III) in LiCoO2 to Co(II), which enhances the leaching efficiency, while methanesulfonic acid serves as the primary lixiviant.
What is the environmental benefit of using organic acids over inorganic acids?
Organic acids like methanesulfonic acid and citric acid are biodegradable and less harmful to the environment compared to inorganic acids such as sulfuric acid, reducing the environmental impact of the recycling process.
What is the activation energy for the leaching of Co and Li?
The activation energies for Co and Li leaching are 50.98 kJ/mol and 50.55 kJ/mol, respectively, indicating a chemical reaction-controlled process.
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