2023 Fiscal Year Annual Research Report
Low/no-corrosion leaching of spent lithium-ion battery cathode materials in hydrothermal water using amino acid or mixed organic acids as the leachant
| Project/Area Number |
21K12302
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| Research Institution | Tohoku University |
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Principal Investigator |
鄭 慶新 東北大学, 工学研究科, 特任助教 (30835509)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | Lithium-ion batteries / Hydrothermal leaching / Mixed organic acids / Continuous / Kinetic study / Metal isolation / Mn isolation |
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| Outline of Annual Research Achievements |
Hydrothermal leaching of spent LiNixCoyMn1-x-yO2 (NCM) and commercial LiMn2O4 (LMO) cathode materials was conducted by applying glycine as a leaching agent. With the increase in reaction temperature and time, the leaching efficiencies of Co, Ni, and Mn significantly increased, but even at 200 °C for 15 min, the leaching efficiency of Mn was as low as 16%. Compared with Li, Co, and Ni, the leaching performance of Mn was much poorer, but this special property makes it possible for glycine to isolate Mn directly from LMO cathode material.
During the hydrothermal leaching of commercial LMO cathode material with glycine, the leaching efficiency of Li significantly increased with reaction temperature and time, and was much higher than that of Mn under the same condition. The results of kinetic study revealed that the activation energy of Li leaching was much lower than that of Mn. At 200 °C for 120 min, the leaching efficiencies of Li and Mn achieved 99.5% and 7.6%, respectively, which means that 92.4% of Mn was successfully isolated and kept in the solid residue. After calcinating at 600 °C for 1h, the final product was obtained and identified to be Mn2O3 with a purity of 99.0%.
Furtheremore, the metal isolation of the leachates obtained from the hydrothermal leaching of commercial NCM cathode materials with mixed organic acids has been studied in depth. Mn was successfully precipitated by alkaline from the leachate in the first step, making it possible to realize the robotic arm-assisted continuous precipitation isolation of Mn, Co, Ni, and Li.
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